diff --git a/vendor/go.opentelemetry.io/otel/.gitignore b/vendor/go.opentelemetry.io/otel/.gitignore
new file mode 100644
index 0000000..cbef197
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/.gitignore
@@ -0,0 +1,22 @@
+.DS_Store
+Thumbs.db
+
+.tools/
+.idea/
+.vscode/
+*.iml
+*.so
+coverage.*
+
+gen/
+
+/example/basic/basic
+/example/grpc/client/client
+/example/grpc/server/server
+/example/http/client/client
+/example/http/server/server
+/example/jaeger/jaeger
+/example/namedtracer/namedtracer
+/example/prometheus/prometheus
+/example/zipkin/zipkin
+/example/otel-collector/otel-collector
diff --git a/vendor/go.opentelemetry.io/otel/.gitmodules b/vendor/go.opentelemetry.io/otel/.gitmodules
new file mode 100644
index 0000000..38a1f56
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "opentelemetry-proto"]
+	path = exporters/otlp/internal/opentelemetry-proto
+	url = https://github.com/open-telemetry/opentelemetry-proto
diff --git a/vendor/go.opentelemetry.io/otel/.golangci.yml b/vendor/go.opentelemetry.io/otel/.golangci.yml
new file mode 100644
index 0000000..2ef1681
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/.golangci.yml
@@ -0,0 +1,32 @@
+# See https://github.com/golangci/golangci-lint#config-file
+run:
+  issues-exit-code: 1 #Default
+  tests: true #Default
+
+linters:
+  enable:
+    - misspell
+    - goimports
+    - golint
+    - gofmt
+
+issues:
+  exclude-rules:
+    # helpers in tests often (rightfully) pass a *testing.T as their first argument
+    - path: _test\.go
+      text: "context.Context should be the first parameter of a function"
+      linters:
+        - golint
+    # Yes, they are, but it's okay in a test
+    - path: _test\.go
+      text: "exported func.*returns unexported type.*which can be annoying to use"
+      linters:
+        - golint
+
+linters-settings:
+  misspell:
+    locale: US
+    ignore-words:
+      - cancelled
+  goimports:
+    local-prefixes: go.opentelemetry.io
diff --git a/vendor/go.opentelemetry.io/otel/CHANGELOG.md b/vendor/go.opentelemetry.io/otel/CHANGELOG.md
new file mode 100644
index 0000000..1b77504
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/CHANGELOG.md
@@ -0,0 +1,922 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
+
+This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [0.13.0] - 2020-10-08
+
+### Added
+
+- OTLP Metric exporter supports Histogram aggregation. (#1209)
+- The `Code` struct from the `go.opentelemetry.io/otel/codes` package now supports JSON marshaling and unmarshaling as well as implements the `Stringer` interface. (#1214)
+- A Baggage API to implement the OpenTelemetry specification. (#1217)
+
+### Changed
+
+- Set default propagator to no-op propagator. (#1184)
+- The `HTTPSupplier`, `HTTPExtractor`, `HTTPInjector`, and `HTTPPropagator` from the `go.opentelemetry.io/otel/api/propagation` package were replaced with unified `TextMapCarrier` and `TextMapPropagator` in the `go.opentelemetry.io/otel` package. (#1212)
+- The `New` function from the `go.opentelemetry.io/otel/api/propagation` package was replaced with `NewCompositeTextMapPropagator` in the `go.opentelemetry.io/otel` package. (#1212)
+- The status codes of the `go.opentelemetry.io/otel/codes` package have been updated to match the latest OpenTelemetry specification.
+   They now are `Unset`, `Error`, and `Ok`.
+   They no longer track the gRPC codes. (#1214)
+- The `StatusCode` field of the `SpanData` struct in the `go.opentelemetry.io/otel/sdk/export/trace` package now uses the codes package from this package instead of the gRPC project. (#1214)
+- Move the `go.opentelemetry.io/otel/api/baggage` package into `go.opentelemetry.io/otel/propagators`. (#1217)
+
+### Fixed
+
+- Copies of data from arrays and slices passed to `go.opentelemetry.io/otel/label.ArrayValue()` are now used in the returned `Value` instead of using the mutable data itself. (#1226)
+
+### Removed
+
+- The `ExtractHTTP` and `InjectHTTP` functions from the `go.opentelemetry.io/otel/api/propagation` package were removed. (#1212)
+- The `Propagators` interface from the `go.opentelemetry.io/otel/api/propagation` package was removed to conform to the OpenTelemetry specification.
+   The explicit `TextMapPropagator` type can be used in its place as this is the `Propagator` type the specification defines. (#1212)
+- The `SetAttribute` method of the `Span` from the `go.opentelemetry.io/otel/api/trace` package was removed given its redundancy with the `SetAttributes` method. (#1216)
+- The internal implementation of Baggage storage is removed in favor of using the new Baggage API functionality. (#1217)
+- Remove duplicate hostname key `HostHostNameKey` in Resource semantic conventions. (#1219)
+- Nested array/slice support has been removed. (#1226)
+
+## [0.12.0] - 2020-09-24
+
+### Added
+
+- A `SpanConfigure` function in `go.opentelemetry.io/otel/api/trace` to create a new `SpanConfig` from `SpanOption`s. (#1108)
+- In the `go.opentelemetry.io/otel/api/trace` package, `NewTracerConfig` was added to construct new `TracerConfig`s.
+   This addition was made to conform with our project option conventions. (#1155)
+- Instrumentation library information was added to the Zipkin exporter. (#1119)
+- The `SpanProcessor` interface now has a `ForceFlush()` method. (#1166)
+- More semantic conventions for k8s as resource attributes. (#1167)
+
+### Changed
+
+- Add reconnecting udp connection type to Jaeger exporter.
+   This change adds a new optional implementation of the udp conn interface used to detect changes to an agent's host dns record.
+   It then adopts the new destination address to ensure the exporter doesn't get stuck. This change was ported from jaegertracing/jaeger-client-go#520. (#1063)
+- Replace `StartOption` and `EndOption` in `go.opentelemetry.io/otel/api/trace` with `SpanOption`.
+   This change is matched by replacing the `StartConfig` and `EndConfig` with a unified `SpanConfig`. (#1108)
+- Replace the `LinkedTo` span option in `go.opentelemetry.io/otel/api/trace` with `WithLinks`.
+   This is be more consistent with our other option patterns, i.e. passing the item to be configured directly instead of its component parts, and provides a cleaner function signature. (#1108)
+- The `go.opentelemetry.io/otel/api/trace` `TracerOption` was changed to an interface to conform to project option conventions. (#1109)
+- Move the `B3` and `TraceContext` from within the `go.opentelemetry.io/otel/api/trace` package to their own `go.opentelemetry.io/otel/propagators` package.
+    This removal of the propagators is reflective of the OpenTelemetry specification for these propagators as well as cleans up the `go.opentelemetry.io/otel/api/trace` API. (#1118)
+- Rename Jaeger tags used for instrumentation library information to reflect changes in OpenTelemetry specification. (#1119)
+- Rename `ProbabilitySampler` to `TraceIDRatioBased` and change semantics to ignore parent span sampling status. (#1115)
+- Move `tools` package under `internal`. (#1141)
+- Move `go.opentelemetry.io/otel/api/correlation` package to `go.opentelemetry.io/otel/api/baggage`. (#1142)
+   The `correlation.CorrelationContext` propagator has been renamed `baggage.Baggage`.  Other exported functions and types are unchanged.
+- Rename `ParentOrElse` sampler to `ParentBased` and allow setting samplers depending on parent span. (#1153)
+- In the `go.opentelemetry.io/otel/api/trace` package, `SpanConfigure` was renamed to `NewSpanConfig`. (#1155)
+- Change `dependabot.yml` to add a `Skip Changelog` label to dependabot-sourced PRs. (#1161)
+- The [configuration style guide](https://github.com/open-telemetry/opentelemetry-go/blob/master/CONTRIBUTING.md#config) has been updated to
+   recommend the use of `newConfig()` instead of `configure()`. (#1163)
+- The `otlp.Config` type has been unexported and changed to `otlp.config`, along with its initializer. (#1163)
+- Ensure exported interface types include parameter names and update the
+   Style Guide to reflect this styling rule. (#1172)
+- Don't consider unset environment variable for resource detection to be an error. (#1170)
+- Rename `go.opentelemetry.io/otel/api/metric.ConfigureInstrument` to `NewInstrumentConfig` and
+  `go.opentelemetry.io/otel/api/metric.ConfigureMeter` to `NewMeterConfig`.
+- ValueObserver instruments use LastValue aggregator by default. (#1165)
+- OTLP Metric exporter supports LastValue aggregation. (#1165)
+- Move the `go.opentelemetry.io/otel/api/unit` package to `go.opentelemetry.io/otel/unit`. (#1185)
+- Rename `Provider` to `MeterProvider` in the `go.opentelemetry.io/otel/api/metric` package. (#1190)
+- Rename `NoopProvider` to `NoopMeterProvider` in the `go.opentelemetry.io/otel/api/metric` package. (#1190)
+- Rename `NewProvider` to `NewMeterProvider` in the `go.opentelemetry.io/otel/api/metric/metrictest` package. (#1190)
+- Rename `Provider` to `MeterProvider` in the `go.opentelemetry.io/otel/api/metric/registry` package. (#1190)
+- Rename `NewProvider` to `NewMeterProvider` in the `go.opentelemetry.io/otel/api/metri/registryc` package. (#1190)
+- Rename `Provider` to `TracerProvider` in the `go.opentelemetry.io/otel/api/trace` package. (#1190)
+- Rename `NoopProvider` to `NoopTracerProvider` in the `go.opentelemetry.io/otel/api/trace` package. (#1190)
+- Rename `Provider` to `TracerProvider` in the `go.opentelemetry.io/otel/api/trace/tracetest` package. (#1190)
+- Rename `NewProvider` to `NewTracerProvider` in the `go.opentelemetry.io/otel/api/trace/tracetest` package. (#1190)
+- Rename `WrapperProvider` to `WrapperTracerProvider` in the `go.opentelemetry.io/otel/bridge/opentracing` package. (#1190)
+- Rename `NewWrapperProvider` to `NewWrapperTracerProvider` in the `go.opentelemetry.io/otel/bridge/opentracing` package. (#1190)
+- Rename `Provider` method of the pull controller to `MeterProvider` in the `go.opentelemetry.io/otel/sdk/metric/controller/pull` package. (#1190)
+- Rename `Provider` method of the push controller to `MeterProvider` in the `go.opentelemetry.io/otel/sdk/metric/controller/push` package. (#1190)
+- Rename `ProviderOptions` to `TracerProviderConfig` in the `go.opentelemetry.io/otel/sdk/trace` package. (#1190)
+- Rename `ProviderOption` to `TracerProviderOption` in the `go.opentelemetry.io/otel/sdk/trace` package. (#1190)
+- Rename `Provider` to `TracerProvider` in the `go.opentelemetry.io/otel/sdk/trace` package. (#1190)
+- Rename `NewProvider` to `NewTracerProvider` in the `go.opentelemetry.io/otel/sdk/trace` package. (#1190)
+- Renamed `SamplingDecision` values to comply with OpenTelemetry specification change. (#1192)
+- Renamed Zipkin attribute names from `ot.status_code & ot.status_description` to `otel.status_code & otel.status_description`. (#1201)
+- The default SDK now invokes registered `SpanProcessor`s in the order they were registered with the `TracerProvider`. (#1195)
+- Add test of spans being processed by the `SpanProcessor`s in the order they were registered. (#1203)
+
+### Removed
+
+- Remove the B3 propagator from `go.opentelemetry.io/otel/propagators`. It is now located in the
+   `go.opentelemetry.io/contrib/propagators/` module. (#1191)
+- Remove the semantic convention for HTTP status text, `HTTPStatusTextKey` from package `go.opentelemetry.io/otel/semconv`. (#1194)
+
+### Fixed
+
+- Zipkin example no longer mentions `ParentSampler`, corrected to `ParentBased`. (#1171)
+- Fix missing shutdown processor in otel-collector example. (#1186)
+- Fix missing shutdown processor in basic and namedtracer examples. (#1197)
+
+## [0.11.0] - 2020-08-24
+
+### Added
+
+- Support for exporting array-valued attributes via OTLP. (#992)
+- `Noop` and `InMemory` `SpanBatcher` implementations to help with testing integrations. (#994)
+- Support for filtering metric label sets. (#1047)
+- A dimensionality-reducing metric Processor. (#1057)
+- Integration tests for more OTel Collector Attribute types. (#1062)
+- A new `WithSpanProcessor` `ProviderOption` is added to the `go.opentelemetry.io/otel/sdk/trace` package to create a `Provider` and automatically register the `SpanProcessor`. (#1078)
+
+### Changed
+
+- Rename `sdk/metric/processor/test` to `sdk/metric/processor/processortest`. (#1049)
+- Rename `sdk/metric/controller/test` to `sdk/metric/controller/controllertest`. (#1049)
+- Rename `api/testharness` to `api/apitest`. (#1049)
+- Rename `api/trace/testtrace` to `api/trace/tracetest`. (#1049)
+- Change Metric Processor to merge multiple observations. (#1024)
+- The `go.opentelemetry.io/otel/bridge/opentracing` bridge package has been made into its own module.
+   This removes the package dependencies of this bridge from the rest of the OpenTelemetry based project. (#1038)
+- Renamed `go.opentelemetry.io/otel/api/standard` package to `go.opentelemetry.io/otel/semconv` to avoid the ambiguous and generic name `standard` and better describe the package as containing OpenTelemetry semantic conventions. (#1016)
+- The environment variable used for resource detection has been changed from `OTEL_RESOURCE_LABELS` to `OTEL_RESOURCE_ATTRIBUTES` (#1042)
+- Replace `WithSyncer` with `WithBatcher` in examples. (#1044)
+- Replace the `google.golang.org/grpc/codes` dependency in the API with an equivalent `go.opentelemetry.io/otel/codes` package. (#1046)
+- Merge the `go.opentelemetry.io/otel/api/label` and `go.opentelemetry.io/otel/api/kv` into the new `go.opentelemetry.io/otel/label` package. (#1060)
+- Unify Callback Function Naming.
+   Rename `*Callback` with `*Func`. (#1061)
+- CI builds validate against last two versions of Go, dropping 1.13 and adding 1.15. (#1064)
+- The `go.opentelemetry.io/otel/sdk/export/trace` interfaces `SpanSyncer` and `SpanBatcher` have been replaced with a specification compliant `Exporter` interface.
+   This interface still supports the export of `SpanData`, but only as a slice.
+   Implementation are also required now to return any error from `ExportSpans` if one occurs as well as implement a `Shutdown` method for exporter clean-up. (#1078)
+- The `go.opentelemetry.io/otel/sdk/trace` `NewBatchSpanProcessor` function no longer returns an error.
+   If a `nil` exporter is passed as an argument to this function, instead of it returning an error, it now returns a `BatchSpanProcessor` that handles the export of `SpanData` by not taking any action. (#1078)
+- The `go.opentelemetry.io/otel/sdk/trace` `NewProvider` function to create a `Provider` no longer returns an error, instead only a `*Provider`.
+   This change is related to `NewBatchSpanProcessor` not returning an error which was the only error this function would return. (#1078)
+
+### Removed
+
+- Duplicate, unused API sampler interface. (#999)
+   Use the [`Sampler` interface](https://github.com/open-telemetry/opentelemetry-go/blob/v0.11.0/sdk/trace/sampling.go) provided by the SDK instead.
+- The `grpctrace` instrumentation was moved to the `go.opentelemetry.io/contrib` repository and out of this repository.
+   This move includes moving the `grpc` example to the `go.opentelemetry.io/contrib` as well. (#1027)
+- The `WithSpan` method of the `Tracer` interface.
+   The functionality this method provided was limited compared to what a user can provide themselves.
+   It was removed with the understanding that if there is sufficient user need it can be added back based on actual user usage. (#1043)
+- The `RegisterSpanProcessor` and `UnregisterSpanProcessor` functions.
+   These were holdovers from an approach prior to the TracerProvider design. They were not used anymore. (#1077)
+- The `oterror` package. (#1026)
+- The `othttp` and `httptrace` instrumentations were moved to `go.opentelemetry.io/contrib`. (#1032)
+
+### Fixed
+
+- The `semconv.HTTPServerMetricAttributesFromHTTPRequest()` function no longer generates the high-cardinality `http.request.content.length` label. (#1031)
+- Correct instrumentation version tag in Jaeger exporter. (#1037)
+- The SDK span will now set an error event if the `End` method is called during a panic (i.e. it was deferred). (#1043)
+- Move internally generated protobuf code from the `go.opentelemetry.io/otel` to the OTLP exporter to reduce dependency overhead. (#1050)
+- The `otel-collector` example referenced outdated collector processors. (#1006)
+
+## [0.10.0] - 2020-07-29
+
+This release migrates the default OpenTelemetry SDK into its own Go module, decoupling the SDK from the API and reducing dependencies for instrumentation packages.
+
+### Added
+
+- The Zipkin exporter now has `NewExportPipeline` and `InstallNewPipeline` constructor functions to match the common pattern.
+    These function build a new exporter with default SDK options and register the exporter with the `global` package respectively. (#944)
+- Add propagator option for gRPC instrumentation. (#986)
+- The `testtrace` package now tracks the `trace.SpanKind` for each span. (#987)
+
+### Changed
+
+- Replace the `RegisterGlobal` `Option` in the Jaeger exporter with an `InstallNewPipeline` constructor function.
+   This matches the other exporter constructor patterns and will register a new exporter after building it with default configuration. (#944)
+- The trace (`go.opentelemetry.io/otel/exporters/trace/stdout`) and metric (`go.opentelemetry.io/otel/exporters/metric/stdout`) `stdout` exporters are now merged into a single exporter at `go.opentelemetry.io/otel/exporters/stdout`.
+   This new exporter was made into its own Go module to follow the pattern of all exporters and decouple it from the `go.opentelemetry.io/otel` module. (#956, #963)
+- Move the `go.opentelemetry.io/otel/exporters/test` test package to `go.opentelemetry.io/otel/sdk/export/metric/metrictest`. (#962)
+- The `go.opentelemetry.io/otel/api/kv/value` package was merged into the parent `go.opentelemetry.io/otel/api/kv` package. (#968)
+  - `value.Bool` was replaced with `kv.BoolValue`.
+  - `value.Int64` was replaced with `kv.Int64Value`.
+  - `value.Uint64` was replaced with `kv.Uint64Value`.
+  - `value.Float64` was replaced with `kv.Float64Value`.
+  - `value.Int32` was replaced with `kv.Int32Value`.
+  - `value.Uint32` was replaced with `kv.Uint32Value`.
+  - `value.Float32` was replaced with `kv.Float32Value`.
+  - `value.String` was replaced with `kv.StringValue`.
+  - `value.Int` was replaced with `kv.IntValue`.
+  - `value.Uint` was replaced with `kv.UintValue`.
+  - `value.Array` was replaced with `kv.ArrayValue`.
+- Rename `Infer` to `Any` in the `go.opentelemetry.io/otel/api/kv` package. (#972)
+- Change `othttp` to use the `httpsnoop` package to wrap the `ResponseWriter` so that optional interfaces (`http.Hijacker`, `http.Flusher`, etc.) that are implemented by the original `ResponseWriter`are also implemented by the wrapped `ResponseWriter`. (#979)
+- Rename `go.opentelemetry.io/otel/sdk/metric/aggregator/test` package to `go.opentelemetry.io/otel/sdk/metric/aggregator/aggregatortest`. (#980)
+- Make the SDK into its own Go module called `go.opentelemetry.io/otel/sdk`. (#985)
+- Changed the default trace `Sampler` from `AlwaysOn` to `ParentOrElse(AlwaysOn)`. (#989)
+
+### Removed
+
+- The `IndexedAttribute` function from the `go.opentelemetry.io/otel/api/label` package was removed in favor of `IndexedLabel` which it was synonymous with. (#970)
+
+### Fixed
+
+- Bump github.com/golangci/golangci-lint from 1.28.3 to 1.29.0 in /tools. (#953)
+- Bump github.com/google/go-cmp from 0.5.0 to 0.5.1. (#957)
+- Use `global.Handle` for span export errors in the OTLP exporter. (#946)
+- Correct Go language formatting in the README documentation. (#961)
+- Remove default SDK dependencies from the `go.opentelemetry.io/otel/api` package. (#977)
+- Remove default SDK dependencies from the `go.opentelemetry.io/otel/instrumentation` package. (#983)
+- Move documented examples for `go.opentelemetry.io/otel/instrumentation/grpctrace` interceptors into Go example tests. (#984)
+
+## [0.9.0] - 2020-07-20
+
+### Added
+
+- A new Resource Detector interface is included to allow resources to be automatically detected and included. (#939)
+- A Detector to automatically detect resources from an environment variable. (#939)
+- Github action to generate protobuf Go bindings locally in `internal/opentelemetry-proto-gen`. (#938)
+- OTLP .proto files from `open-telemetry/opentelemetry-proto` imported as a git submodule under `internal/opentelemetry-proto`.
+   References to `github.com/open-telemetry/opentelemetry-proto` changed to `go.opentelemetry.io/otel/internal/opentelemetry-proto-gen`. (#942)
+
+### Changed
+
+- Non-nil value `struct`s for key-value pairs will be marshalled using JSON rather than `Sprintf`. (#948)
+
+### Removed
+
+- Removed dependency on `github.com/open-telemetry/opentelemetry-collector`. (#943)
+
+## [0.8.0] - 2020-07-09
+
+### Added
+
+- The `B3Encoding` type to represent the B3 encoding(s) the B3 propagator can inject.
+   A value for HTTP supported encodings (Multiple Header: `MultipleHeader`, Single Header: `SingleHeader`) are included. (#882)
+- The `FlagsDeferred` trace flag to indicate if the trace sampling decision has been deferred. (#882)
+- The `FlagsDebug` trace flag to indicate if the trace is a debug trace. (#882)
+- Add `peer.service` semantic attribute. (#898)
+- Add database-specific semantic attributes. (#899)
+- Add semantic convention for `faas.coldstart` and `container.id`. (#909)
+- Add http content size semantic conventions. (#905)
+- Include `http.request_content_length` in HTTP request basic attributes. (#905)
+- Add semantic conventions for operating system process resource attribute keys. (#919)
+- The Jaeger exporter now has a `WithBatchMaxCount` option to specify the maximum number of spans sent in a batch. (#931)
+
+### Changed
+
+- Update `CONTRIBUTING.md` to ask for updates to `CHANGELOG.md` with each pull request. (#879)
+- Use lowercase header names for B3 Multiple Headers. (#881)
+- The B3 propagator `SingleHeader` field has been replaced with `InjectEncoding`.
+   This new field can be set to combinations of the `B3Encoding` bitmasks and will inject trace information in these encodings.
+   If no encoding is set, the propagator will default to `MultipleHeader` encoding. (#882)
+- The B3 propagator now extracts from either HTTP encoding of B3 (Single Header or Multiple Header) based on what is contained in the header.
+   Preference is given to Single Header encoding with Multiple Header being the fallback if Single Header is not found or is invalid.
+   This behavior change is made to dynamically support all correctly encoded traces received instead of having to guess the expected encoding prior to receiving. (#882)
+- Extend semantic conventions for RPC. (#900)
+- To match constant naming conventions in the `api/standard` package, the `FaaS*` key names are appended with a suffix of `Key`. (#920)
+  - `"api/standard".FaaSName` -> `FaaSNameKey`
+  - `"api/standard".FaaSID` -> `FaaSIDKey`
+  - `"api/standard".FaaSVersion` -> `FaaSVersionKey`
+  - `"api/standard".FaaSInstance` -> `FaaSInstanceKey`
+
+### Removed
+
+- The `FlagsUnused` trace flag is removed.
+   The purpose of this flag was to act as the inverse of `FlagsSampled`, the inverse of `FlagsSampled` is used instead. (#882)
+- The B3 header constants (`B3SingleHeader`, `B3DebugFlagHeader`, `B3TraceIDHeader`, `B3SpanIDHeader`, `B3SampledHeader`, `B3ParentSpanIDHeader`) are removed.
+   If B3 header keys are needed [the authoritative OpenZipkin package constants](https://pkg.go.dev/github.com/openzipkin/zipkin-go@v0.2.2/propagation/b3?tab=doc#pkg-constants) should be used instead. (#882)
+
+### Fixed
+
+- The B3 Single Header name is now correctly `b3` instead of the previous `X-B3`. (#881)
+- The B3 propagator now correctly supports sampling only values (`b3: 0`, `b3: 1`, or `b3: d`) for a Single B3 Header. (#882)
+- The B3 propagator now propagates the debug flag.
+   This removes the behavior of changing the debug flag into a set sampling bit.
+   Instead, this now follow the B3 specification and omits the `X-B3-Sampling` header. (#882)
+- The B3 propagator now tracks "unset" sampling state (meaning "defer the decision") and does not set the `X-B3-Sampling` header when injecting. (#882)
+- Bump github.com/itchyny/gojq from 0.10.3 to 0.10.4 in /tools. (#883)
+- Bump github.com/opentracing/opentracing-go from v1.1.1-0.20190913142402-a7454ce5950e to v1.2.0. (#885)
+- The tracing time conversion for OTLP spans is now correctly set to `UnixNano`. (#896)
+- Ensure span status is not set to `Unknown` when no HTTP status code is provided as it is assumed to be `200 OK`. (#908)
+- Ensure `httptrace.clientTracer` closes `http.headers` span. (#912)
+- Prometheus exporter will not apply stale updates or forget inactive metrics. (#903)
+- Add test for api.standard `HTTPClientAttributesFromHTTPRequest`. (#905)
+- Bump github.com/golangci/golangci-lint from 1.27.0 to 1.28.1 in /tools. (#901, #913)
+- Update otel-colector example to use the v0.5.0 collector. (#915)
+- The `grpctrace` instrumentation uses a span name conforming to the OpenTelemetry semantic conventions (does not contain a leading slash (`/`)). (#922)
+- The `grpctrace` instrumentation includes an `rpc.method` attribute now set to the gRPC method name. (#900, #922)
+- The `grpctrace` instrumentation `rpc.service` attribute now contains the package name if one exists.
+   This is in accordance with OpenTelemetry semantic conventions. (#922)
+- Correlation Context extractor will no longer insert an empty map into the returned context when no valid values are extracted. (#923)
+- Bump google.golang.org/api from 0.28.0 to 0.29.0 in /exporters/trace/jaeger. (#925)
+- Bump github.com/itchyny/gojq from 0.10.4 to 0.11.0 in /tools. (#926)
+- Bump github.com/golangci/golangci-lint from 1.28.1 to 1.28.2 in /tools. (#930)
+
+## [0.7.0] - 2020-06-26
+
+This release implements the v0.5.0 version of the OpenTelemetry specification.
+
+### Added
+
+- The othttp instrumentation now includes default metrics. (#861)
+- This CHANGELOG file to track all changes in the project going forward.
+- Support for array type attributes. (#798)
+- Apply transitive dependabot go.mod dependency updates as part of a new automatic Github workflow. (#844)
+- Timestamps are now passed to exporters for each export. (#835)
+- Add new `Accumulation` type to metric SDK to transport telemetry from `Accumulator`s to `Processor`s.
+   This replaces the prior `Record` `struct` use for this purpose. (#835)
+- New dependabot integration to automate package upgrades. (#814)
+- `Meter` and `Tracer` implementations accept instrumentation version version as an optional argument.
+   This instrumentation version is passed on to exporters. (#811) (#805) (#802)
+- The OTLP exporter includes the instrumentation version in telemetry it exports. (#811)
+- Environment variables for Jaeger exporter are supported. (#796)
+- New `aggregation.Kind` in the export metric API. (#808)
+- New example that uses OTLP and the collector. (#790)
+- Handle errors in the span `SetName` during span initialization. (#791)
+- Default service config to enable retries for retry-able failed requests in the OTLP exporter and an option to override this default. (#777)
+- New `go.opentelemetry.io/otel/api/oterror` package to uniformly support error handling and definitions for the project. (#778)
+- New `global` default implementation of the `go.opentelemetry.io/otel/api/oterror.Handler` interface to be used to handle errors prior to an user defined `Handler`.
+   There is also functionality for the user to register their `Handler` as well as a convenience function `Handle` to handle an error with this global `Handler`(#778)
+- Options to specify propagators for httptrace and grpctrace instrumentation. (#784)
+- The required `application/json` header for the Zipkin exporter is included in all exports. (#774)
+- Integrate HTTP semantics helpers from the contrib repository into the `api/standard` package. #769
+
+### Changed
+
+- Rename `Integrator` to `Processor` in the metric SDK. (#863)
+- Rename `AggregationSelector` to `AggregatorSelector`. (#859)
+- Rename `SynchronizedCopy` to `SynchronizedMove`. (#858)
+- Rename `simple` integrator to `basic` integrator. (#857)
+- Merge otlp collector examples. (#841)
+- Change the metric SDK to support cumulative, delta, and pass-through exporters directly.
+   With these changes, cumulative and delta specific exporters are able to request the correct kind of aggregation from the SDK. (#840)
+- The `Aggregator.Checkpoint` API is renamed to `SynchronizedCopy` and adds an argument, a different `Aggregator` into which the copy is stored. (#812)
+- The `export.Aggregator` contract is that `Update()` and `SynchronizedCopy()` are synchronized with each other.
+   All the aggregation interfaces (`Sum`, `LastValue`, ...) are not meant to be synchronized, as the caller is expected to synchronize aggregators at a higher level after the `Accumulator`.
+   Some of the `Aggregators` used unnecessary locking and that has been cleaned up. (#812)
+- Use of `metric.Number` was replaced by `int64` now that we use `sync.Mutex` in the `MinMaxSumCount` and `Histogram` `Aggregators`. (#812)
+- Replace `AlwaysParentSample` with `ParentSample(fallback)` to match the OpenTelemetry v0.5.0 specification. (#810)
+- Rename `sdk/export/metric/aggregator` to `sdk/export/metric/aggregation`. #808
+- Send configured headers with every request in the OTLP exporter, instead of just on connection creation. (#806)
+- Update error handling for any one off error handlers, replacing, instead, with the `global.Handle` function. (#791)
+- Rename `plugin` directory to `instrumentation` to match the OpenTelemetry specification. (#779)
+- Makes the argument order to Histogram and DDSketch `New()` consistent. (#781)
+
+### Removed
+
+- `Uint64NumberKind` and related functions from the API. (#864)
+- Context arguments from `Aggregator.Checkpoint` and `Integrator.Process` as they were unused. (#803)
+- `SpanID` is no longer included in parameters for sampling decision to match the OpenTelemetry specification. (#775)
+
+### Fixed
+
+- Upgrade OTLP exporter to opentelemetry-proto matching the opentelemetry-collector v0.4.0 release. (#866)
+- Allow changes to `go.sum` and `go.mod` when running dependabot tidy-up. (#871)
+- Bump github.com/stretchr/testify from 1.4.0 to 1.6.1. (#824)
+- Bump github.com/prometheus/client_golang from 1.7.0 to 1.7.1 in /exporters/metric/prometheus. (#867)
+- Bump google.golang.org/grpc from 1.29.1 to 1.30.0 in /exporters/trace/jaeger. (#853)
+- Bump google.golang.org/grpc from 1.29.1 to 1.30.0 in /exporters/trace/zipkin. (#854)
+- Bumps github.com/golang/protobuf from 1.3.2 to 1.4.2 (#848)
+- Bump github.com/stretchr/testify from 1.4.0 to 1.6.1 in /exporters/otlp (#817)
+- Bump github.com/golangci/golangci-lint from 1.25.1 to 1.27.0 in /tools (#828)
+- Bump github.com/prometheus/client_golang from 1.5.0 to 1.7.0 in /exporters/metric/prometheus (#838)
+- Bump github.com/stretchr/testify from 1.4.0 to 1.6.1 in /exporters/trace/jaeger (#829)
+- Bump github.com/benbjohnson/clock from 1.0.0 to 1.0.3 (#815)
+- Bump github.com/stretchr/testify from 1.4.0 to 1.6.1 in /exporters/trace/zipkin (#823)
+- Bump github.com/itchyny/gojq from 0.10.1 to 0.10.3 in /tools (#830)
+- Bump github.com/stretchr/testify from 1.4.0 to 1.6.1 in /exporters/metric/prometheus (#822)
+- Bump google.golang.org/grpc from 1.27.1 to 1.29.1 in /exporters/trace/zipkin (#820)
+- Bump google.golang.org/grpc from 1.27.1 to 1.29.1 in /exporters/trace/jaeger (#831)
+- Bump github.com/google/go-cmp from 0.4.0 to 0.5.0 (#836)
+- Bump github.com/google/go-cmp from 0.4.0 to 0.5.0 in /exporters/trace/jaeger (#837)
+- Bump github.com/google/go-cmp from 0.4.0 to 0.5.0 in /exporters/otlp (#839)
+- Bump google.golang.org/api from 0.20.0 to 0.28.0 in /exporters/trace/jaeger (#843)
+- Set span status from HTTP status code in the othttp instrumentation. (#832)
+- Fixed typo in push controller comment. (#834)
+- The `Aggregator` testing has been updated and cleaned. (#812)
+- `metric.Number(0)` expressions are replaced by `0` where possible. (#812)
+- Fixed `global` `handler_test.go` test failure. #804
+- Fixed `BatchSpanProcessor.Shutdown` to wait until all spans are processed. (#766)
+- Fixed OTLP example's accidental early close of exporter. (#807)
+- Ensure zipkin exporter reads and closes response body. (#788)
+- Update instrumentation to use `api/standard` keys instead of custom keys. (#782)
+- Clean up tools and RELEASING documentation. (#762)
+
+## [0.6.0] - 2020-05-21
+
+### Added
+
+- Support for `Resource`s in the prometheus exporter. (#757)
+- New pull controller. (#751)
+- New `UpDownSumObserver` instrument. (#750)
+- OpenTelemetry collector demo. (#711)
+- New `SumObserver` instrument. (#747)
+- New `UpDownCounter` instrument. (#745)
+- New timeout `Option` and configuration function `WithTimeout` to the push controller. (#742)
+- New `api/standards` package to implement semantic conventions and standard key-value generation. (#731)
+
+### Changed
+
+- Rename `Register*` functions in the metric API to `New*` for all `Observer` instruments. (#761)
+- Use `[]float64` for histogram boundaries, not `[]metric.Number`. (#758)
+- Change OTLP example to use exporter as a trace `Syncer` instead of as an unneeded `Batcher`. (#756)
+- Replace `WithResourceAttributes()` with `WithResource()` in the trace SDK. (#754)
+- The prometheus exporter now uses the new pull controller. (#751)
+- Rename `ScheduleDelayMillis` to `BatchTimeout` in the trace `BatchSpanProcessor`.(#752)
+- Support use of synchronous instruments in asynchronous callbacks (#725)
+- Move `Resource` from the `Export` method parameter into the metric export `Record`. (#739)
+- Rename `Observer` instrument to `ValueObserver`. (#734)
+- The push controller now has a method (`Provider()`) to return a `metric.Provider` instead of the old `Meter` method that acted as a `metric.Provider`. (#738)
+- Replace `Measure` instrument by `ValueRecorder` instrument. (#732)
+- Rename correlation context header from `"Correlation-Context"` to `"otcorrelations"` to match the OpenTelemetry specification. 727)
+
+### Fixed
+
+- Ensure gRPC `ClientStream` override methods do not panic in grpctrace package. (#755)
+- Disable parts of `BatchSpanProcessor` test until a fix is found. (#743)
+- Fix `string` case in `kv` `Infer` function. (#746)
+- Fix panic in grpctrace client interceptors. (#740)
+- Refactor the `api/metrics` push controller and add `CheckpointSet` synchronization. (#737)
+- Rewrite span batch process queue batching logic. (#719)
+- Remove the push controller named Meter map. (#738)
+- Fix Histogram aggregator initial state (fix #735). (#736)
+- Ensure golang alpine image is running `golang-1.14` for examples. (#733)
+- Added test for grpctrace `UnaryInterceptorClient`. (#695)
+- Rearrange `api/metric` code layout. (#724)
+
+## [0.5.0] - 2020-05-13
+
+### Added
+
+- Batch `Observer` callback support. (#717)
+- Alias `api` types to root package of project. (#696)
+- Create basic `othttp.Transport` for simple client instrumentation. (#678)
+- `SetAttribute(string, interface{})` to the trace API. (#674)
+- Jaeger exporter option that allows user to specify custom http client. (#671)
+- `Stringer` and `Infer` methods to `key`s. (#662)
+
+### Changed
+
+- Rename `NewKey` in the `kv` package to just `Key`. (#721)
+- Move `core` and `key` to `kv` package. (#720)
+- Make the metric API `Meter` a `struct` so the abstract `MeterImpl` can be passed and simplify implementation. (#709)
+- Rename SDK `Batcher` to `Integrator` to match draft OpenTelemetry SDK specification. (#710)
+- Rename SDK `Ungrouped` integrator to `simple.Integrator` to match draft OpenTelemetry SDK specification. (#710)
+- Rename SDK `SDK` `struct` to `Accumulator` to match draft OpenTelemetry SDK specification. (#710)
+- Move `Number` from `core` to `api/metric` package. (#706)
+- Move `SpanContext` from `core` to `trace` package. (#692)
+- Change traceparent header from `Traceparent` to `traceparent` to implement the W3C specification. (#681)
+
+### Fixed
+
+- Update tooling to run generators in all submodules. (#705)
+- gRPC interceptor regexp to match methods without a service name. (#683)
+- Use a `const` for padding 64-bit B3 trace IDs. (#701)
+- Update `mockZipkin` listen address from `:0` to `127.0.0.1:0`. (#700)
+- Left-pad 64-bit B3 trace IDs with zero. (#698)
+- Propagate at least the first W3C tracestate header. (#694)
+- Remove internal `StateLocker` implementation. (#688)
+- Increase instance size CI system uses. (#690)
+- Add a `key` benchmark and use reflection in `key.Infer()`. (#679)
+- Fix internal `global` test by using `global.Meter` with `RecordBatch()`. (#680)
+- Reimplement histogram using mutex instead of `StateLocker`. (#669)
+- Switch `MinMaxSumCount` to a mutex lock implementation instead of `StateLocker`. (#667)
+- Update documentation to not include any references to `WithKeys`. (#672)
+- Correct misspelling. (#668)
+- Fix clobbering of the span context if extraction fails. (#656)
+- Bump `golangci-lint` and work around the corrupting bug. (#666) (#670)
+
+## [0.4.3] - 2020-04-24
+
+### Added
+
+- `Dockerfile` and `docker-compose.yml` to run example code. (#635)
+- New `grpctrace` package that provides gRPC client and server interceptors for both unary and stream connections. (#621)
+- New `api/label` package, providing common label set implementation. (#651)
+- Support for JSON marshaling of `Resources`. (#654)
+- `TraceID` and `SpanID` implementations for `Stringer` interface. (#642)
+- `RemoteAddrKey` in the othttp plugin to include the HTTP client address in top-level spans. (#627)
+- `WithSpanFormatter` option to the othttp plugin. (#617)
+- Updated README to include section for compatible libraries and include reference to the contrib repository. (#612)
+- The prometheus exporter now supports exporting histograms. (#601)
+- A `String` method to the `Resource` to return a hashable identifier for a now unique resource. (#613)
+- An `Iter` method to the `Resource` to return an array `AttributeIterator`. (#613)
+- An `Equal` method to the `Resource` test the equivalence of resources. (#613)
+- An iterable structure (`AttributeIterator`) for `Resource` attributes.
+
+### Changed
+
+- zipkin export's `NewExporter` now requires a `serviceName` argument to ensure this needed values is provided. (#644)
+- Pass `Resources` through the metrics export pipeline. (#659)
+
+### Removed
+
+- `WithKeys` option from the metric API. (#639)
+
+### Fixed
+
+- Use the `label.Set.Equivalent` value instead of an encoding in the batcher. (#658)
+- Correct typo `trace.Exporter` to `trace.SpanSyncer` in comments. (#653)
+- Use type names for return values in jaeger exporter. (#648)
+- Increase the visibility of the `api/key` package by updating comments and fixing usages locally. (#650)
+- `Checkpoint` only after `Update`; Keep records in the `sync.Map` longer. (#647)
+- Do not cache `reflect.ValueOf()` in metric Labels. (#649)
+- Batch metrics exported from the OTLP exporter based on `Resource` and labels. (#626)
+- Add error wrapping to the prometheus exporter. (#631)
+- Update the OTLP exporter batching of traces to use a unique `string` representation of an associated `Resource` as the batching key. (#623)
+- Update OTLP `SpanData` transform to only include the `ParentSpanID` if one exists. (#614)
+- Update `Resource` internal representation to uniquely and reliably identify resources. (#613)
+- Check return value from `CheckpointSet.ForEach` in prometheus exporter. (#622)
+- Ensure spans created by httptrace client tracer reflect operation structure. (#618)
+- Create a new recorder rather than reuse when multiple observations in same epoch for asynchronous instruments. #610
+- The default port the OTLP exporter uses to connect to the OpenTelemetry collector is updated to match the one the collector listens on by default. (#611)
+
+
+## [0.4.2] - 2020-03-31
+
+### Fixed
+
+- Fix `pre_release.sh` to update version in `sdk/opentelemetry.go`. (#607)
+- Fix time conversion from internal to OTLP in OTLP exporter. (#606)
+
+## [0.4.1] - 2020-03-31
+
+### Fixed
+
+- Update `tag.sh` to create signed tags. (#604)
+
+## [0.4.0] - 2020-03-30
+
+### Added
+
+- New API package `api/metric/registry` that exposes a `MeterImpl` wrapper for use by SDKs to generate unique instruments. (#580)
+- Script to verify examples after a new release. (#579)
+
+### Removed
+
+- The dogstatsd exporter due to lack of support.
+   This additionally removes support for statsd. (#591)
+- `LabelSet` from the metric API.
+   This is replaced by a `[]core.KeyValue` slice. (#595)
+- `Labels` from the metric API's `Meter` interface. (#595)
+
+### Changed
+
+- The metric `export.Labels` became an interface which the SDK implements and the `export` package provides a simple, immutable implementation of this interface intended for testing purposes. (#574)
+- Renamed `internal/metric.Meter` to `MeterImpl`. (#580)
+- Renamed `api/global/internal.obsImpl` to `asyncImpl`. (#580)
+
+### Fixed
+
+- Corrected missing return in mock span. (#582)
+- Update License header for all source files to match CNCF guidelines and include a test to ensure it is present. (#586) (#596)
+- Update to v0.3.0 of the OTLP in the OTLP exporter. (#588)
+- Update pre-release script to be compatible between GNU and BSD based systems. (#592)
+- Add a `RecordBatch` benchmark. (#594)
+- Moved span transforms of the OTLP exporter to the internal package. (#593)
+- Build both go-1.13 and go-1.14 in circleci to test for all supported versions of Go. (#569)
+- Removed unneeded allocation on empty labels in OLTP exporter. (#597)
+- Update `BatchedSpanProcessor` to process the queue until no data but respect max batch size. (#599)
+- Update project documentation godoc.org links to pkg.go.dev. (#602)
+
+## [0.3.0] - 2020-03-21
+
+This is a first official beta release, which provides almost fully complete metrics, tracing, and context propagation functionality.
+There is still a possibility of breaking changes.
+
+### Added
+
+- Add `Observer` metric instrument. (#474)
+- Add global `Propagators` functionality to enable deferred initialization for propagators registered before the first Meter SDK is installed. (#494)
+- Simplified export setup pipeline for the jaeger exporter to match other exporters. (#459)
+- The zipkin trace exporter. (#495)
+- The OTLP exporter to export metric and trace telemetry to the OpenTelemetry collector. (#497) (#544) (#545)
+- The `StatusMessage` field was add to the trace `Span`. (#524)
+- Context propagation in OpenTracing bridge in terms of OpenTelemetry context propagation. (#525)
+- The `Resource` type was added to the SDK. (#528)
+- The global API now supports a `Tracer` and `Meter` function as shortcuts to getting a global `*Provider` and calling these methods directly. (#538)
+- The metric API now defines a generic `MeterImpl` interface to support general purpose `Meter` construction.
+   Additionally, `SyncImpl` and `AsyncImpl` are added to support general purpose instrument construction. (#560)
+- A metric `Kind` is added to represent the `MeasureKind`, `ObserverKind`, and `CounterKind`. (#560)
+- Scripts to better automate the release process. (#576)
+
+### Changed
+
+- Default to to use `AlwaysSampler` instead of `ProbabilitySampler` to match OpenTelemetry specification. (#506)
+- Renamed `AlwaysSampleSampler` to `AlwaysOnSampler` in the trace API. (#511)
+- Renamed `NeverSampleSampler` to `AlwaysOffSampler` in the trace API. (#511)
+- The `Status` field of the `Span` was changed to `StatusCode` to disambiguate with the added `StatusMessage`. (#524)
+- Updated the trace `Sampler` interface conform to the OpenTelemetry specification. (#531)
+- Rename metric API `Options` to `Config`. (#541)
+- Rename metric `Counter` aggregator to be `Sum`. (#541)
+- Unify metric options into `Option` from instrument specific options. (#541)
+- The trace API's `TraceProvider` now support `Resource`s. (#545)
+- Correct error in zipkin module name. (#548)
+- The jaeger trace exporter now supports `Resource`s. (#551)
+- Metric SDK now supports `Resource`s.
+   The `WithResource` option was added to configure a `Resource` on creation and the `Resource` method was added to the metric `Descriptor` to return the associated `Resource`. (#552)
+- Replace `ErrNoLastValue` and `ErrEmptyDataSet` by `ErrNoData` in the metric SDK. (#557)
+- The stdout trace exporter now supports `Resource`s. (#558)
+- The metric `Descriptor` is now included at the API instead of the SDK. (#560)
+- Replace `Ordered` with an iterator in `export.Labels`. (#567)
+
+### Removed
+
+- The vendor specific Stackdriver. It is now hosted on 3rd party vendor infrastructure. (#452)
+- The `Unregister` method for metric observers as it is not in the OpenTelemetry specification. (#560)
+- `GetDescriptor` from the metric SDK. (#575)
+- The `Gauge` instrument from the metric API. (#537)
+
+### Fixed
+
+- Make histogram aggregator checkpoint consistent. (#438)
+- Update README with import instructions and how to build and test. (#505)
+- The default label encoding was updated to be unique. (#508)
+- Use `NewRoot` in the othttp plugin for public endpoints. (#513)
+- Fix data race in `BatchedSpanProcessor`. (#518)
+- Skip test-386 for Mac OS 10.15.x (Catalina and upwards). #521
+- Use a variable-size array to represent ordered labels in maps. (#523)
+- Update the OTLP protobuf and update changed import path. (#532)
+- Use `StateLocker` implementation in `MinMaxSumCount`. (#546)
+- Eliminate goroutine leak in histogram stress test. (#547)
+- Update OTLP exporter with latest protobuf. (#550)
+- Add filters to the othttp plugin. (#556)
+- Provide an implementation of the `Header*` filters that do not depend on Go 1.14. (#565)
+- Encode labels once during checkpoint.
+   The checkpoint function is executed in a single thread so we can do the encoding lazily before passing the encoded version of labels to the exporter.
+   This is a cheap and quick way to avoid encoding the labels on every collection interval. (#572)
+- Run coverage over all packages in `COVERAGE_MOD_DIR`. (#573)
+
+## [0.2.3] - 2020-03-04
+
+### Added
+
+- `RecordError` method on `Span`s in the trace API to Simplify adding error events to spans. (#473)
+- Configurable push frequency for exporters setup pipeline. (#504)
+
+### Changed
+
+- Rename the `exporter` directory to `exporters`.
+   The `go.opentelemetry.io/otel/exporter/trace/jaeger` package was mistakenly released with a `v1.0.0` tag instead of `v0.1.0`.
+   This resulted in all subsequent releases not becoming the default latest.
+   A consequence of this was that all `go get`s pulled in the incompatible `v0.1.0` release of that package when pulling in more recent packages from other otel packages.
+   Renaming the `exporter` directory to `exporters` fixes this issue by renaming the package and therefore clearing any existing dependency tags.
+   Consequentially, this action also renames *all* exporter packages. (#502)
+
+### Removed
+
+- The `CorrelationContextHeader` constant in the `correlation` package is no longer exported. (#503)
+
+## [0.2.2] - 2020-02-27
+
+### Added
+
+- `HTTPSupplier` interface in the propagation API to specify methods to retrieve and store a single value for a key to be associated with a carrier. (#467)
+- `HTTPExtractor` interface in the propagation API to extract information from an `HTTPSupplier` into a context. (#467)
+- `HTTPInjector` interface in the propagation API to inject information into an `HTTPSupplier.` (#467)
+- `Config` and configuring `Option` to the propagator API. (#467)
+- `Propagators` interface in the propagation API to contain the set of injectors and extractors for all supported carrier formats. (#467)
+- `HTTPPropagator` interface in the propagation API to inject and extract from an `HTTPSupplier.` (#467)
+- `WithInjectors` and `WithExtractors` functions to the propagator API to configure injectors and extractors to use. (#467)
+- `ExtractHTTP` and `InjectHTTP` functions to apply configured HTTP extractors and injectors to a passed context. (#467)
+- Histogram aggregator. (#433)
+- `DefaultPropagator` function and have it return `trace.TraceContext` as the default context propagator. (#456)
+- `AlwaysParentSample` sampler to the trace API. (#455)
+- `WithNewRoot` option function to the trace API to specify the created span should be considered a root span. (#451)
+
+
+### Changed
+
+- Renamed `WithMap` to `ContextWithMap` in the correlation package. (#481)
+- Renamed `FromContext` to `MapFromContext` in the correlation package. (#481)
+- Move correlation context propagation to correlation package. (#479)
+- Do not default to putting remote span context into links. (#480)
+- Propagators extrac
+- `Tracer.WithSpan` updated to accept `StartOptions`. (#472)
+- Renamed `MetricKind` to `Kind` to not stutter in the type usage. (#432)
+- Renamed the `export` package to `metric` to match directory structure. (#432)
+- Rename the `api/distributedcontext` package to `api/correlation`. (#444)
+- Rename the `api/propagators` package to `api/propagation`. (#444)
+- Move the propagators from the `propagators` package into the `trace` API package. (#444)
+- Update `Float64Gauge`, `Int64Gauge`, `Float64Counter`, `Int64Counter`, `Float64Measure`, and `Int64Measure` metric methods to use value receivers instead of pointers. (#462)
+- Moved all dependencies of tools package to a tools directory. (#466)
+
+### Removed
+
+- Binary propagators. (#467)
+- NOOP propagator. (#467)
+
+### Fixed
+
+- Upgraded `github.com/golangci/golangci-lint` from `v1.21.0` to `v1.23.6` in `tools/`. (#492)
+- Fix a possible nil-dereference crash (#478)
+- Correct comments for `InstallNewPipeline` in the stdout exporter. (#483)
+- Correct comments for `InstallNewPipeline` in the dogstatsd exporter. (#484)
+- Correct comments for `InstallNewPipeline` in the prometheus exporter. (#482)
+- Initialize `onError` based on `Config` in prometheus exporter. (#486)
+- Correct module name in prometheus exporter README. (#475)
+- Removed tracer name prefix from span names. (#430)
+- Fix `aggregator_test.go` import package comment. (#431)
+- Improved detail in stdout exporter. (#436)
+- Fix a dependency issue (generate target should depend on stringer, not lint target) in Makefile. (#442)
+- Reorders the Makefile targets within `precommit` target so we generate files and build the code before doing linting, so we can get much nicer errors about syntax errors from the compiler. (#442)
+- Reword function documentation in gRPC plugin. (#446)
+- Send the `span.kind` tag to Jaeger from the jaeger exporter. (#441)
+- Fix `metadataSupplier` in the jaeger exporter to overwrite the header if existing instead of appending to it. (#441)
+- Upgraded to Go 1.13 in CI. (#465)
+- Correct opentelemetry.io URL in trace SDK documentation. (#464)
+- Refactored reference counting logic in SDK determination of stale records. (#468)
+- Add call to `runtime.Gosched` in instrument `acquireHandle` logic to not block the collector. (#469)
+
+## [0.2.1.1] - 2020-01-13
+
+### Fixed
+
+- Use stateful batcher on Prometheus exporter fixing regresion introduced in #395. (#428)
+
+## [0.2.1] - 2020-01-08
+
+### Added
+
+- Global meter forwarding implementation.
+   This enables deferred initialization for metric instruments registered before the first Meter SDK is installed. (#392)
+- Global trace forwarding implementation.
+   This enables deferred initialization for tracers registered before the first Trace SDK is installed. (#406)
+- Standardize export pipeline creation in all exporters. (#395)
+- A testing, organization, and comments for 64-bit field alignment. (#418)
+- Script to tag all modules in the project. (#414)
+
+### Changed
+
+- Renamed `propagation` package to `propagators`. (#362)
+- Renamed `B3Propagator` propagator to `B3`. (#362)
+- Renamed `TextFormatPropagator` propagator to `TextFormat`. (#362)
+- Renamed `BinaryPropagator` propagator to `Binary`. (#362)
+- Renamed `BinaryFormatPropagator` propagator to `BinaryFormat`. (#362)
+- Renamed `NoopTextFormatPropagator` propagator to `NoopTextFormat`. (#362)
+- Renamed `TraceContextPropagator` propagator to `TraceContext`. (#362)
+- Renamed `SpanOption` to `StartOption` in the trace API. (#369)
+- Renamed `StartOptions` to `StartConfig` in the trace API. (#369)
+- Renamed `EndOptions` to `EndConfig` in the trace API. (#369)
+- `Number` now has a pointer receiver for its methods. (#375)
+- Renamed `CurrentSpan` to `SpanFromContext` in the trace API. (#379)
+- Renamed `SetCurrentSpan` to `ContextWithSpan` in the trace API. (#379)
+- Renamed `Message` in Event to `Name` in the trace API. (#389)
+- Prometheus exporter no longer aggregates metrics, instead it only exports them. (#385)
+- Renamed `HandleImpl` to `BoundInstrumentImpl` in the metric API. (#400)
+- Renamed `Float64CounterHandle` to `Float64CounterBoundInstrument` in the metric API. (#400)
+- Renamed `Int64CounterHandle` to `Int64CounterBoundInstrument` in the metric API. (#400)
+- Renamed `Float64GaugeHandle` to `Float64GaugeBoundInstrument` in the metric API. (#400)
+- Renamed `Int64GaugeHandle` to `Int64GaugeBoundInstrument` in the metric API. (#400)
+- Renamed `Float64MeasureHandle` to `Float64MeasureBoundInstrument` in the metric API. (#400)
+- Renamed `Int64MeasureHandle` to `Int64MeasureBoundInstrument` in the metric API. (#400)
+- Renamed `Release` method for bound instruments in the metric API to `Unbind`. (#400)
+- Renamed `AcquireHandle` method for bound instruments in the metric API to `Bind`. (#400)
+- Renamed the `File` option in the stdout exporter to `Writer`. (#404)
+- Renamed all `Options` to `Config` for all metric exports where this wasn't already the case.
+
+### Fixed
+
+- Aggregator import path corrected. (#421)
+- Correct links in README. (#368)
+- The README was updated to match latest code changes in its examples. (#374)
+- Don't capitalize error statements. (#375)
+- Fix ignored errors. (#375)
+- Fix ambiguous variable naming. (#375)
+- Removed unnecessary type casting. (#375)
+- Use named parameters. (#375)
+- Updated release schedule. (#378)
+- Correct http-stackdriver example module name. (#394)
+- Removed the `http.request` span in `httptrace` package. (#397)
+- Add comments in the metrics SDK (#399)
+- Initialize checkpoint when creating ddsketch aggregator to prevent panic when merging into a empty one. (#402) (#403)
+- Add documentation of compatible exporters in the README. (#405)
+- Typo fix. (#408)
+- Simplify span check logic in SDK tracer implementation. (#419)
+
+## [0.2.0] - 2019-12-03
+
+### Added
+
+- Unary gRPC tracing example. (#351)
+- Prometheus exporter. (#334)
+- Dogstatsd metrics exporter. (#326)
+
+### Changed
+
+- Rename `MaxSumCount` aggregation to `MinMaxSumCount` and add the `Min` interface for this aggregation. (#352)
+- Rename `GetMeter` to `Meter`. (#357)
+- Rename `HTTPTraceContextPropagator` to `TraceContextPropagator`. (#355)
+- Rename `HTTPB3Propagator` to `B3Propagator`. (#355)
+- Rename `HTTPTraceContextPropagator` to `TraceContextPropagator`. (#355)
+- Move `/global` package to `/api/global`. (#356)
+- Rename `GetTracer` to `Tracer`. (#347)
+
+### Removed
+
+- `SetAttribute` from the `Span` interface in the trace API. (#361)
+- `AddLink` from the `Span` interface in the trace API. (#349)
+- `Link` from the `Span` interface in the trace API. (#349)
+
+### Fixed
+
+- Exclude example directories from coverage report. (#365)
+- Lint make target now implements automatic fixes with `golangci-lint` before a second run to report the remaining issues. (#360)
+- Drop `GO111MODULE` environment variable in Makefile as Go 1.13 is the project specified minimum version and this is environment variable is not needed for that version of Go. (#359)
+- Run the race checker for all test. (#354)
+- Redundant commands in the Makefile are removed. (#354)
+- Split the `generate` and `lint` targets of the Makefile. (#354)
+- Renames `circle-ci` target to more generic `ci` in Makefile. (#354)
+- Add example Prometheus binary to gitignore. (#358)
+- Support negative numbers with the `MaxSumCount`. (#335)
+- Resolve race conditions in `push_test.go` identified in #339. (#340)
+- Use `/usr/bin/env bash` as a shebang in scripts rather than `/bin/bash`. (#336)
+- Trace benchmark now tests both `AlwaysSample` and `NeverSample`.
+   Previously it was testing `AlwaysSample` twice. (#325)
+- Trace benchmark now uses a `[]byte` for `TraceID` to fix failing test. (#325)
+- Added a trace benchmark to test variadic functions in `setAttribute` vs `setAttributes` (#325)
+- The `defaultkeys` batcher was only using the encoded label set as its map key while building a checkpoint.
+   This allowed distinct label sets through, but any metrics sharing a label set could be overwritten or merged incorrectly.
+   This was corrected. (#333)
+
+
+## [0.1.2] - 2019-11-18
+
+### Fixed
+
+- Optimized the `simplelru` map for attributes to reduce the number of allocations. (#328)
+- Removed unnecessary unslicing of parameters that are already a slice. (#324)
+
+## [0.1.1] - 2019-11-18
+
+This release contains a Metrics SDK with stdout exporter and supports basic aggregations such as counter, gauges, array, maxsumcount, and ddsketch.
+
+### Added
+
+- Metrics stdout export pipeline. (#265)
+- Array aggregation for raw measure metrics. (#282)
+- The core.Value now have a `MarshalJSON` method. (#281)
+
+### Removed
+
+- `WithService`, `WithResources`, and `WithComponent` methods of tracers. (#314)
+- Prefix slash in `Tracer.Start()` for the Jaeger example. (#292)
+
+### Changed
+
+- Allocation in LabelSet construction to reduce GC overhead. (#318)
+- `trace.WithAttributes` to append values instead of replacing (#315)
+- Use a formula for tolerance in sampling tests. (#298)
+- Move export types into trace and metric-specific sub-directories. (#289)
+- `SpanKind` back to being based on an `int` type. (#288)
+
+### Fixed
+
+- URL to OpenTelemetry website in README. (#323)
+- Name of othttp default tracer. (#321)
+- `ExportSpans` for the stackdriver exporter now handles `nil` context. (#294)
+- CI modules cache to correctly restore/save from/to the cache. (#316)
+- Fix metric SDK race condition between `LoadOrStore` and the assignment `rec.recorder = i.meter.exporter.AggregatorFor(rec)`. (#293)
+- README now reflects the new code structure introduced with these changes. (#291)
+- Make the basic example work. (#279)
+
+## [0.1.0] - 2019-11-04
+
+This is the first release of open-telemetry go library.
+It contains api and sdk for trace and meter.
+
+### Added
+
+- Initial OpenTelemetry trace and metric API prototypes.
+- Initial OpenTelemetry trace, metric, and export SDK packages.
+- A wireframe bridge to support compatibility with OpenTracing.
+- Example code for a basic, http-stackdriver, http, jaeger, and named tracer setup.
+- Exporters for Jaeger, Stackdriver, and stdout.
+- Propagators for binary, B3, and trace-context protocols.
+- Project information and guidelines in the form of a README and CONTRIBUTING.
+- Tools to build the project and a Makefile to automate the process.
+- Apache-2.0 license.
+- CircleCI build CI manifest files.
+- CODEOWNERS file to track owners of this project.
+
+
+[Unreleased]: https://github.com/open-telemetry/opentelemetry-go/compare/v0.13.0...HEAD
+[0.13.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.13.0
+[0.12.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.12.0
+[0.11.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.11.0
+[0.10.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.10.0
+[0.9.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.9.0
+[0.8.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.8.0
+[0.7.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.7.0
+[0.6.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.6.0
+[0.5.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.5.0
+[0.4.3]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.4.3
+[0.4.2]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.4.2
+[0.4.1]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.4.1
+[0.4.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.4.0
+[0.3.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.3.0
+[0.2.3]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.2.3
+[0.2.2]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.2.2
+[0.2.1.1]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.2.1.1
+[0.2.1]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.2.1
+[0.2.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.2.0
+[0.1.2]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.1.2
+[0.1.1]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.1.1
+[0.1.0]: https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.1.0
diff --git a/vendor/go.opentelemetry.io/otel/CODEOWNERS b/vendor/go.opentelemetry.io/otel/CODEOWNERS
new file mode 100644
index 0000000..b2e99fc
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/CODEOWNERS
@@ -0,0 +1,17 @@
+#####################################################
+#
+# List of approvers for this repository
+#
+#####################################################
+#
+# Learn about membership in OpenTelemetry community:
+#  https://github.com/open-telemetry/community/blob/master/community-membership.md
+#
+#
+# Learn about CODEOWNERS file format:
+#  https://help.github.com/en/articles/about-code-owners
+#
+
+* @jmacd @lizthegrey @MrAlias @Aneurysm9 @evantorrie @XSAM
+
+CODEOWNERS @MrAlias @Aneurysm9
diff --git a/vendor/go.opentelemetry.io/otel/CONTRIBUTING.md b/vendor/go.opentelemetry.io/otel/CONTRIBUTING.md
new file mode 100644
index 0000000..85d9a09
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/CONTRIBUTING.md
@@ -0,0 +1,373 @@
+# Contributing to opentelemetry-go
+
+The Go special interest group (SIG) meets regularly. See the
+OpenTelemetry
+[community](https://github.com/open-telemetry/community#golang-sdk)
+repo for information on this and other language SIGs.
+
+See the [public meeting
+notes](https://docs.google.com/document/d/1A63zSWX0x2CyCK_LoNhmQC4rqhLpYXJzXbEPDUQ2n6w/edit#heading=h.9tngw7jdwd6b)
+for a summary description of past meetings. To request edit access,
+join the meeting or get in touch on
+[Gitter](https://gitter.im/open-telemetry/opentelemetry-go).
+
+## Development
+
+You can view and edit the source code by cloning this repository:
+
+```bash
+git clone https://github.com/open-telemetry/opentelemetry-go.git
+```
+
+Run `make test` to run the tests instead of `go test`. 
+
+There are some generated files checked into the repo. To make sure
+that the generated files are up-to-date, run `make` (or `make
+precommit` - the `precommit` target is the default).
+
+The `precommit` target also fixes the formatting of the code and
+checks the status of the go module files.
+
+If after running `make precommit` the output of `git status` contains
+`nothing to commit, working tree clean` then it means that everything
+is up-to-date and properly formatted.
+
+## Pull Requests
+
+### How to Send Pull Requests
+
+Everyone is welcome to contribute code to `opentelemetry-go` via
+GitHub pull requests (PRs).
+
+To create a new PR, fork the project in GitHub and clone the upstream
+repo:
+
+```sh
+$ go get -d go.opentelemetry.io/otel
+```
+
+(This may print some warning about "build constraints exclude all Go
+files", just ignore it.)
+
+This will put the project in `${GOPATH}/src/go.opentelemetry.io/otel`. You
+can alternatively use `git` directly with:
+
+```sh
+$ git clone https://github.com/open-telemetry/opentelemetry-go
+```
+
+(Note that `git clone` is *not* using the `go.opentelemetry.io/otel` name -
+that name is a kind of a redirector to GitHub that `go get` can
+understand, but `git` does not.)
+
+This would put the project in the `opentelemetry-go` directory in
+current working directory.
+
+Enter the newly created directory and add your fork as a new remote:
+
+```sh
+$ git remote add <YOUR_FORK> git@github.com:<YOUR_GITHUB_USERNAME>/opentelemetry-go
+```
+
+Check out a new branch, make modifications, run linters and tests, update
+`CHANGELOG.md`, and push the branch to your fork:
+
+```sh
+$ git checkout -b <YOUR_BRANCH_NAME>
+# edit files
+# update changelog
+$ make precommit
+$ git add -p
+$ git commit
+$ git push <YOUR_FORK> <YOUR_BRANCH_NAME>
+```
+
+Open a pull request against the main `opentelemetry-go` repo. Be sure to add the pull
+request ID to the entry you added to `CHANGELOG.md`.
+
+### How to Receive Comments
+
+* If the PR is not ready for review, please put `[WIP]` in the title,
+  tag it as `work-in-progress`, or mark it as
+  [`draft`](https://github.blog/2019-02-14-introducing-draft-pull-requests/).
+* Make sure CLA is signed and CI is clear.
+
+### How to Get PRs Merged
+
+A PR is considered to be **ready to merge** when:
+
+* It has received two approvals from Collaborators/Maintainers (at
+  different companies). This is not enforced through technical means
+  and a PR may be **ready to merge** with a single approval if the change
+  and its approach have been discussed and consensus reached.
+* Major feedbacks are resolved.
+* It has been open for review for at least one working day. This gives
+  people reasonable time to review.
+* Trivial changes (typo, cosmetic, doc, etc.) do not have to wait for
+  one day and may be merged with a single Maintainer's approval.
+* `CHANGELOG.md` has been updated to reflect what has been
+  added, changed, removed, or fixed.
+* Urgent fix can take exception as long as it has been actively
+  communicated.
+
+Any Maintainer can merge the PR once it is **ready to merge**.
+
+## Design Choices
+
+As with other OpenTelemetry clients, opentelemetry-go follows the
+[opentelemetry-specification](https://github.com/open-telemetry/opentelemetry-specification).
+
+It's especially valuable to read through the [library
+guidelines](https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/library-guidelines.md).
+
+### Focus on Capabilities, Not Structure Compliance
+
+OpenTelemetry is an evolving specification, one where the desires and
+use cases are clear, but the method to satisfy those uses cases are
+not.
+
+As such, Contributions should provide functionality and behavior that
+conforms to the specification, but the interface and structure is
+flexible.
+
+It is preferable to have contributions follow the idioms of the
+language rather than conform to specific API names or argument
+patterns in the spec.
+
+For a deeper discussion, see:
+https://github.com/open-telemetry/opentelemetry-specification/issues/165
+
+## Style Guide
+
+One of the primary goals of this project is that it is actually used by
+developers. With this goal in mind the project strives to build
+user-friendly and idiomatic Go code adhering to the Go community's best
+practices.
+
+For a non-comprehensive but foundational overview of these best practices
+the [Effective Go](https://golang.org/doc/effective_go.html) documentation
+is an excellent starting place.
+
+As a convenience for developers building this project the `make precommit`
+will format, lint, validate, and in some cases fix the changes you plan to
+submit. This check will need to pass for your changes to be able to be
+merged.
+
+In addition to idiomatic Go, the project has adopted certain standards for
+implementations of common patterns. These standards should be followed as a
+default, and if they are not followed documentation needs to be included as
+to the reasons why.
+
+### Configuration
+
+When creating an instantiation function for a complex `struct` it is useful
+to allow variable number of options to be applied. However, the strong type
+system of Go restricts the function design options. There are a few ways to
+solve this problem, but we have landed on the following design.
+
+#### `config`
+
+Configuration should be held in a `struct` named `config`, or prefixed with
+specific type name this Configuration applies to if there are multiple
+`config` in the package. This `struct` must contain configuration options.
+
+```go
+// config contains configuration options for a thing.
+type config struct {
+    // options ...
+}
+```
+
+In general the `config` `struct` will not need to be used externally to the
+package and should be unexported. If, however, it is expected that the user
+will likely want to build custom options for the configuration, the `config`
+should be exported. Please, include in the documentation for the `config`
+how the user can extend the configuration.
+
+It is important that `config` are not shared across package boundaries.
+Meaning a `config` from one package should not be directly used by another.
+
+Optionally, it is common to include a `newConfig` function (with the same
+naming scheme). This function wraps any defaults setting and looping over
+all options to create a configured `config`.
+
+```go
+// newConfig returns an appropriately configured config.
+func newConfig([]Option) config {
+    // Set default values for config.
+    config := config{/* […] */}
+    for _, option := range options {
+        option.Apply(&config)
+    }
+    // Preform any validation here.
+    return config
+}
+```
+
+If validation of the `config` options is also preformed this can return an
+error as well that is expected to be handled by the instantiation function
+or propagated to the user.
+
+Given the design goal of not having the user need to work with the `config`,
+the `newConfig` function should also be unexported.
+
+#### `Option`
+
+To set the value of the options a `config` contains, a corresponding
+`Option` interface type should be used.
+
+```go
+type Option interface {
+  Apply(*config)
+}
+```
+
+The name of the interface should be prefixed in the same way the
+corresponding `config` is (if at all).
+
+#### Options
+
+All user configurable options for a `config` must have a related unexported
+implementation of the `Option` interface and an exported configuration
+function that wraps this implementation.
+
+The wrapping function name should be prefixed with `With*` (or in the
+special case of a boolean options `Without*`) and should have the following
+function signature.
+
+```go
+func With*(…) Option { … }
+```
+
+##### `bool` Options
+
+```go
+type defaultFalseOption bool
+
+func (o defaultFalseOption) Apply(c *config) {
+    c.Bool = bool(o)
+}
+
+// WithOption sets a T* to have an option included.
+func WithOption() Option {
+    return defaultFalseOption(true)
+}
+```
+
+```go
+type defaultTrueOption bool
+
+func (o defaultTrueOption) Apply(c *config) {
+    c.Bool = bool(o)
+}
+
+// WithoutOption sets a T* to have Bool option excluded.
+func WithoutOption() Option {
+    return defaultTrueOption(false)
+}
+````
+
+##### Declared Type Options
+
+```go
+type myTypeOption struct {
+    MyType MyType
+}
+
+func (o myTypeOption) Apply(c *config) {
+    c.MyType = o.MyType
+}
+
+// WithMyType sets T* to have include MyType.
+func WithMyType(t MyType) Option {
+    return myTypeOption{t}
+}
+```
+
+#### Instantiation
+
+Using this configuration pattern to configure instantiation with a `New*`
+function.
+
+```go
+func NewT*(options ...Option) T* {…}
+```
+
+Any required parameters can be declared before the variadic `options`.
+
+#### Dealing with Overlap
+
+Sometimes there are multiple complex `struct` that share common
+configuration and also have distinct configuration. To avoid repeated
+portions of `config`s, a common `config` can be used with the union of
+options being handled with the `Option` interface.
+
+For example.
+
+```go
+// config holds options for all animals.
+type config struct {
+	Weight      float64
+	Color       string
+	MaxAltitude float64
+}
+
+// DogOption apply Dog specific options.
+type DogOption interface {
+	ApplyDog(*config)
+}
+
+// BirdOption apply Bird specific options.
+type BirdOption interface {
+	ApplyBird(*config)
+}
+
+// Option apply options for all animals.
+type Option interface {
+	BirdOption
+	DogOption
+}
+
+type weightOption float64
+func (o weightOption) ApplyDog(c *config)  { c.Weight = float64(o) }
+func (o weightOption) ApplyBird(c *config) { c.Weight = float64(o) }
+func WithWeight(w float64) Option          { return weightOption(w) }
+
+type furColorOption string
+func (o furColorOption) ApplyDog(c *config) { c.Color = string(o) }
+func WithFurColor(c string) DogOption       { return furColorOption(c) }
+
+type maxAltitudeOption float64
+func (o maxAltitudeOption) ApplyBird(c *config) { c.MaxAltitude = float64(o) }
+func WithMaxAltitude(a float64) BirdOption      { return maxAltitudeOption(a) }
+
+func NewDog(name string, o ...DogOption) Dog    {…}
+func NewBird(name string, o ...BirdOption) Bird {…}
+```
+
+### Interface Type
+
+To allow other developers to better comprehend the code, it is important
+to ensure it is sufficiently documented. One simple measure that contributes
+to this aim is self-documenting by naming method parameters. Therefore,
+where appropriate, methods of every exported interface type should have
+their parameters appropriately named.
+
+## Approvers and Maintainers
+
+Approvers:
+
+- [Liz Fong-Jones](https://github.com/lizthegrey), Honeycomb
+- [Evan Torrie](https://github.com/evantorrie), Verizon Media
+- [Josh MacDonald](https://github.com/jmacd), LightStep
+- [Sam Xie](https://github.com/XSAM)
+
+Maintainers:
+
+- [Anthony Mirabella](https://github.com/Aneurysm9), Centene
+- [Tyler Yahn](https://github.com/MrAlias), New Relic
+
+### Become an Approver or a Maintainer
+
+See the [community membership document in OpenTelemetry community
+repo](https://github.com/open-telemetry/community/blob/master/community-membership.md).
diff --git a/vendor/go.opentelemetry.io/otel/LICENSE b/vendor/go.opentelemetry.io/otel/LICENSE
new file mode 100644
index 0000000..261eeb9
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/LICENSE
@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
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+      form, that is based on (or derived from) the Work and for which the
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+      "Contribution" shall mean any work of authorship, including
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+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
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+   6. Trademarks. This License does not grant permission to use the trade
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+
+   7. Disclaimer of Warranty. Unless required by applicable law or
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+      Contributor provides its Contributions) on an "AS IS" BASIS,
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+      negligent acts) or agreed to in writing, shall any Contributor be
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+
+       http://www.apache.org/licenses/LICENSE-2.0
+
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diff --git a/vendor/go.opentelemetry.io/otel/Makefile b/vendor/go.opentelemetry.io/otel/Makefile
new file mode 100644
index 0000000..85506a3
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/Makefile
@@ -0,0 +1,177 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+EXAMPLES := $(shell ./get_main_pkgs.sh ./example)
+TOOLS_MOD_DIR := ./internal/tools
+
+# All source code and documents. Used in spell check.
+ALL_DOCS := $(shell find . -name '*.md' -type f | sort)
+# All directories with go.mod files related to opentelemetry library. Used for building, testing and linting.
+ALL_GO_MOD_DIRS := $(filter-out $(TOOLS_MOD_DIR), $(shell find . -type f -name 'go.mod' -exec dirname {} \; | sort))
+ALL_COVERAGE_MOD_DIRS := $(shell find . -type f -name 'go.mod' -exec dirname {} \; | egrep -v '^./example|^$(TOOLS_MOD_DIR)' | sort)
+
+# Mac OS Catalina 10.5.x doesn't support 386. Hence skip 386 test
+SKIP_386_TEST = false
+UNAME_S := $(shell uname -s)
+ifeq ($(UNAME_S),Darwin)
+	SW_VERS := $(shell sw_vers -productVersion)
+	ifeq ($(shell echo $(SW_VERS) | egrep '^(10.1[5-9]|1[1-9]|[2-9])'), $(SW_VERS))
+		SKIP_386_TEST = true
+	endif
+endif
+
+GOTEST_MIN = go test -timeout 30s
+GOTEST = $(GOTEST_MIN) -race
+GOTEST_WITH_COVERAGE = $(GOTEST) -coverprofile=coverage.out -covermode=atomic -coverpkg=./...
+
+.DEFAULT_GOAL := precommit
+
+.PHONY: precommit
+
+TOOLS_DIR := $(abspath ./.tools)
+
+$(TOOLS_DIR)/golangci-lint: $(TOOLS_MOD_DIR)/go.mod $(TOOLS_MOD_DIR)/go.sum $(TOOLS_MOD_DIR)/tools.go
+	cd $(TOOLS_MOD_DIR) && \
+	go build -o $(TOOLS_DIR)/golangci-lint github.com/golangci/golangci-lint/cmd/golangci-lint
+
+$(TOOLS_DIR)/misspell: $(TOOLS_MOD_DIR)/go.mod $(TOOLS_MOD_DIR)/go.sum $(TOOLS_MOD_DIR)/tools.go
+	cd $(TOOLS_MOD_DIR) && \
+	go build -o $(TOOLS_DIR)/misspell github.com/client9/misspell/cmd/misspell
+
+$(TOOLS_DIR)/stringer: $(TOOLS_MOD_DIR)/go.mod $(TOOLS_MOD_DIR)/go.sum $(TOOLS_MOD_DIR)/tools.go
+	cd $(TOOLS_MOD_DIR) && \
+	go build -o $(TOOLS_DIR)/stringer golang.org/x/tools/cmd/stringer
+
+$(TOOLS_DIR)/gojq: $(TOOLS_MOD_DIR)/go.mod $(TOOLS_MOD_DIR)/go.sum $(TOOLS_MOD_DIR)/tools.go
+	cd $(TOOLS_MOD_DIR) && \
+	go build -o $(TOOLS_DIR)/gojq github.com/itchyny/gojq/cmd/gojq
+
+precommit: dependabot-check license-check generate build lint examples test-benchmarks test
+
+.PHONY: test-with-coverage
+test-with-coverage:
+	set -e; \
+	printf "" > coverage.txt; \
+	for dir in $(ALL_COVERAGE_MOD_DIRS); do \
+	  echo "go test ./... + coverage in $${dir}"; \
+	  (cd "$${dir}" && \
+	 	$(GOTEST_WITH_COVERAGE) ./... && \
+		go tool cover -html=coverage.out -o coverage.html); \
+      [ -f "$${dir}/coverage.out" ] && cat "$${dir}/coverage.out" >> coverage.txt; \
+	done; \
+	sed -i.bak -e '2,$$ { /^mode: /d; }' coverage.txt
+
+
+.PHONY: ci
+ci: precommit check-clean-work-tree test-with-coverage test-386
+
+.PHONY: check-clean-work-tree
+check-clean-work-tree:
+	@if ! git diff --quiet; then \
+	  echo; \
+	  echo 'Working tree is not clean, did you forget to run "make precommit"?'; \
+	  echo; \
+	  git status; \
+	  exit 1; \
+	fi
+
+.PHONY: build
+build:
+	# TODO: Fix this on windows.
+	set -e; for dir in $(ALL_GO_MOD_DIRS); do \
+	  echo "compiling all packages in $${dir}"; \
+	  (cd "$${dir}" && \
+	    go build ./... && \
+	    go test -run xxxxxMatchNothingxxxxx ./... >/dev/null); \
+	done
+
+.PHONY: test
+test:
+	set -e; for dir in $(ALL_GO_MOD_DIRS); do \
+	  echo "go test ./... + race in $${dir}"; \
+	  (cd "$${dir}" && \
+	    $(GOTEST) ./...); \
+	done
+
+.PHONY: test-386
+test-386:
+	if [ $(SKIP_386_TEST) = true ] ; then \
+	  echo "skipping the test for GOARCH 386 as it is not supported on the current OS"; \
+	else \
+	  set -e; for dir in $(ALL_GO_MOD_DIRS); do \
+	    echo "go test ./... GOARCH 386 in $${dir}"; \
+	    (cd "$${dir}" && \
+	      GOARCH=386 $(GOTEST_MIN) ./...); \
+	  done; \
+	fi
+
+.PHONY: examples
+examples:
+	@set -e; for ex in $(EXAMPLES); do \
+	  echo "Building $${ex}"; \
+	  (cd "$${ex}" && \
+	   go build .); \
+	done
+
+.PHONY: test-benchmarks
+test-benchmarks:
+	@set -e; for dir in $(ALL_GO_MOD_DIRS); do \
+	  echo "test benchmarks in $${dir}"; \
+	  (cd "$${dir}" && go test -test.benchtime=1ms -run=NONE -bench=. ./...) > /dev/null; \
+	done
+
+.PHONY: lint
+lint: $(TOOLS_DIR)/golangci-lint $(TOOLS_DIR)/misspell
+	set -e; for dir in $(ALL_GO_MOD_DIRS); do \
+	  echo "golangci-lint in $${dir}"; \
+	  (cd "$${dir}" && \
+	    $(TOOLS_DIR)/golangci-lint run --fix && \
+	    $(TOOLS_DIR)/golangci-lint run); \
+	done
+	$(TOOLS_DIR)/misspell -w $(ALL_DOCS)
+	set -e; for dir in $(ALL_GO_MOD_DIRS) $(TOOLS_MOD_DIR); do \
+	  echo "go mod tidy in $${dir}"; \
+	  (cd "$${dir}" && \
+	    go mod tidy); \
+	done
+
+generate: $(TOOLS_DIR)/stringer
+	set -e; for dir in $(ALL_GO_MOD_DIRS); do \
+	  echo "running generators in $${dir}"; \
+	  (cd "$${dir}" && \
+	    PATH="$(TOOLS_DIR):$${PATH}" go generate ./...); \
+	done
+
+.PHONY: license-check
+license-check:
+	@licRes=$$(for f in $$(find . -type f \( -iname '*.go' -o -iname '*.sh' \) ! -path './vendor/*' ! -path './exporters/otlp/internal/opentelemetry-proto/*') ; do \
+	           awk '/Copyright The OpenTelemetry Authors|generated|GENERATED/ && NR<=3 { found=1; next } END { if (!found) print FILENAME }' $$f; \
+	   done); \
+	   if [ -n "$${licRes}" ]; then \
+	           echo "license header checking failed:"; echo "$${licRes}"; \
+	           exit 1; \
+	   fi
+
+.PHONY: dependabot-check
+dependabot-check:
+	@result=$$( \
+		for f in $$( find . -type f -name go.mod -exec dirname {} \; | sed 's/^.\/\?/\//' ); \
+			do grep -q "$$f" .github/dependabot.yml \
+			|| echo "$$f"; \
+		done; \
+	); \
+	if [ -n "$$result" ]; then \
+		echo "missing go.mod dependabot check:"; echo "$$result"; \
+		exit 1; \
+	fi
diff --git a/vendor/go.opentelemetry.io/otel/Makefile.proto b/vendor/go.opentelemetry.io/otel/Makefile.proto
new file mode 100644
index 0000000..417c3b3
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/Makefile.proto
@@ -0,0 +1,72 @@
+#   -*- mode: makefile; -*-
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# This Makefile.proto has rules to generate *.pb.go files in
+# `exporters/otlp/internal/opentelemetry-proto-gen` from the .proto files in
+# `exporters/otlp/internal/opentelemetry-proto` using protoc with a go plugin.
+#
+# The protoc binary and other tools are sourced from a docker image
+# `PROTOC_IMAGE`.
+#
+# Prereqs: The archiving utility `pax` is installed.
+
+PROTOC_IMAGE          := namely/protoc-all:1.29_2
+PROTOBUF_VERSION      := v1
+OTEL_PROTO_SUBMODULE  := exporters/otlp/internal/opentelemetry-proto
+PROTOBUF_GEN_DIR      := exporters/otlp/internal/opentelemetry-proto-gen
+PROTOBUF_TEMP_DIR     := gen/pb-go
+PROTO_SOURCE_DIR      := gen/proto
+SUBMODULE_PROTO_FILES := $(wildcard $(OTEL_PROTO_SUBMODULE)/opentelemetry/proto/*/$(PROTOBUF_VERSION)/*.proto \
+                           $(OTEL_PROTO_SUBMODULE)/opentelemetry/proto/collector/*/$(PROTOBUF_VERSION)/*.proto)
+SOURCE_PROTO_FILES    := $(subst $(OTEL_PROTO_SUBMODULE),$(PROTO_SOURCE_DIR),$(SUBMODULE_PROTO_FILES))
+
+default: protobuf
+
+.PHONY: protobuf protobuf-source gen-protobuf copy-protobufs
+protobuf: protobuf-source gen-protobuf copy-protobufs
+
+protobuf-source: $(SOURCE_PROTO_FILES) | $(PROTO_SOURCE_DIR)/
+
+# Changes go_package in .proto file to point to repo-local location
+define exec-replace-pkgname
+sed  's,go_package = "github.com/open-telemetry/opentelemetry-proto/gen/go,go_package = "go.opentelemetry.io/otel/exporters/otlp/internal/opentelemetry-proto-gen,' < $(1) > $(2)
+
+endef
+
+# replace opentelemetry-proto package name by go.opentelemetry.io/otel specific version
+$(SOURCE_PROTO_FILES): $(PROTO_SOURCE_DIR)/%.proto: $(OTEL_PROTO_SUBMODULE)/%.proto
+	@mkdir -p $(@D)
+	$(call exec-replace-pkgname,$<,$@)
+
+# Command to run protoc using docker image
+define exec-protoc-all
+docker run -v `pwd`:/defs $(PROTOC_IMAGE) $(1)
+
+endef
+
+gen-protobuf: $(SOURCE_PROTO_FILES) | $(PROTOBUF_GEN_DIR)/
+	$(foreach file,$(subst ${PROTO_SOURCE_DIR}/,,$(SOURCE_PROTO_FILES)),$(call exec-protoc-all, -i $(PROTO_SOURCE_DIR) -f ${file} -l gogo -o ${PROTOBUF_TEMP_DIR}))
+
+# requires `pax` to be installed, as it has consistent options for both BSD (Darwin) and Linux
+copy-protobufs: | $(PROTOBUF_GEN_DIR)/
+	find ./$(PROTOBUF_TEMP_DIR)/go.opentelemetry.io/otel/$(PROTOBUF_GEN_DIR) -type f -print0 | \
+      pax -0 -s ',^./$(PROTOBUF_TEMP_DIR)/go.opentelemetry.io/otel/$(PROTOBUF_GEN_DIR),,' -rw ./$(PROTOBUF_GEN_DIR)
+
+$(PROTO_SOURCE_DIR)/ $(PROTOBUF_GEN_DIR)/:
+	mkdir -p $@
+
+.PHONY: clean
+clean:
+	rm -rf ./gen
diff --git a/vendor/go.opentelemetry.io/otel/README.md b/vendor/go.opentelemetry.io/otel/README.md
new file mode 100644
index 0000000..e45f05e
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/README.md
@@ -0,0 +1,57 @@
+# OpenTelemetry-Go
+
+[![Circle CI](https://circleci.com/gh/open-telemetry/opentelemetry-go.svg?style=svg)](https://circleci.com/gh/open-telemetry/opentelemetry-go)
+[![Docs](https://godoc.org/go.opentelemetry.io/otel?status.svg)](https://pkg.go.dev/go.opentelemetry.io/otel)
+[![Go Report Card](https://goreportcard.com/badge/go.opentelemetry.io/otel)](https://goreportcard.com/report/go.opentelemetry.io/otel)
+[![Gitter](https://badges.gitter.im/open-telemetry/opentelemetry-go.svg)](https://gitter.im/open-telemetry/opentelemetry-go?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
+
+The Go [OpenTelemetry](https://opentelemetry.io/) implementation.
+
+## Getting Started
+
+OpenTelemetry's goal is to provide a single set of APIs to capture distributed
+traces and metrics from your application and send them to an observability
+platform. This project allows you to do just that for applications written in
+Go. There are two steps to this process: instrument your application, and
+configure an exporter.
+
+### Instrumentation
+
+To start capturing distributed traces and metric events from your application
+it first needs to be instrumented. The easiest way to do this is by using an
+instrumentation library for your code. Be sure to check out [the officially
+supported instrumentation
+libraries](https://github.com/open-telemetry/opentelemetry-go-contrib/tree/master/instrumentation).
+
+If you need to extend the telemetry an instrumentation library provides or want
+to build your own instrumentation for your application directly you will need
+to use the
+[go.opentelemetry.io/otel/api](https://pkg.go.dev/go.opentelemetry.io/otel/api)
+package. The included [examples](./example/) are a good way to see some
+practical uses of this process.
+
+### Export
+
+Now that your application is instrumented to collect telemetry, it needs an
+export pipeline to send that telemetry to an observability platform.
+
+You can find officially supported exporters [here](./exporters/) and in the
+companion [contrib
+repository](https://github.com/open-telemetry/opentelemetry-go-contrib/tree/master/exporters/metric).
+Additionally, there are many vendor specific or 3rd party exporters for
+OpenTelemetry. These exporters are broken down by
+[trace](https://pkg.go.dev/go.opentelemetry.io/otel/sdk/export/trace?tab=importedby)
+and
+[metric](https://pkg.go.dev/go.opentelemetry.io/otel/sdk/export/metric?tab=importedby)
+support.
+
+## Project Status
+
+[Project boards](https://github.com/open-telemetry/opentelemetry-go/projects)
+and [milestones](https://github.com/open-telemetry/opentelemetry-go/milestones)
+can be found at the respective links. We try to keep these accurate and should
+be the best place to go for answers on project status.
+
+## Contributing
+
+See the [contributing documentation](CONTRIBUTING.md).
diff --git a/vendor/go.opentelemetry.io/otel/RELEASING.md b/vendor/go.opentelemetry.io/otel/RELEASING.md
new file mode 100644
index 0000000..0fba7f1
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/RELEASING.md
@@ -0,0 +1,81 @@
+# Release Process
+
+## Pre-Release
+
+Update go.mod for submodules to depend on the new release which will happen in the next step.
+
+1. Run the pre-release script. It creates a branch `pre_release_<new tag>` that will contain all release changes.
+
+    ```
+    ./pre_release.sh -t <new tag>
+    ```
+
+2. Verify the changes.
+
+    ```
+    git diff master
+    ```
+
+    This should have changed the version for all modules to be `<new tag>`.
+
+3. Update the [Changelog](./CHANGELOG.md).
+   - Make sure all relevant changes for this release are included and are in language that non-contributors to the project can understand.
+       To verify this, you can look directly at the commits since the `<last tag>`.
+
+       ```
+       git --no-pager log --pretty=oneline "<last tag>..HEAD"
+       ```
+
+   - Move all the `Unreleased` changes into a new section following the title scheme (`[<new tag>] - <date of release>`).
+   - Update all the appropriate links at the bottom.
+
+4. Push the changes to upstream and create a Pull Request on GitHub.
+    Be sure to include the curated changes from the [Changelog](./CHANGELOG.md) in the description.
+
+
+## Tag
+
+Once the Pull Request with all the version changes has been approved and merged it is time to tag the merged commit.
+
+***IMPORTANT***: It is critical you use the same tag that you used in the Pre-Release step!
+Failure to do so will leave things in a broken state.
+
+***IMPORTANT***: [There is currently no way to remove an incorrectly tagged version of a Go module](https://github.com/golang/go/issues/34189).
+It is critical you make sure the version you push upstream is correct.
+[Failure to do so will lead to minor emergencies and tough to work around](https://github.com/open-telemetry/opentelemetry-go/issues/331).
+
+1. Run the tag.sh script using the `<commit-hash>` of the commit on the master branch for the merged Pull Request.
+
+    ```
+    ./tag.sh <new tag> <commit-hash>
+    ```
+
+2. Push tags to the upstream remote (not your fork: `github.com/open-telemetry/opentelemetry-go.git`).
+    Make sure you push all sub-modules as well.
+
+    ```
+    git push upstream <new tag>
+    git push upstream <submodules-path/new tag>
+    ...
+    ```
+
+## Release
+
+Finally create a Release for the new `<new tag>` on GitHub.
+The release body should include all the release notes from the Changelog for this release.
+Additionally, the `tag.sh` script generates commit logs since last release which can be used to supplement the release notes.
+
+## Verify Examples
+
+After releasing verify that examples build outside of the repository.
+
+```
+./verify_examples.sh
+```
+
+The script copies examples into a different directory removes any `replace` declarations in `go.mod` and builds them.
+This ensures they build with the published release, not the local copy.
+
+## Contrib Repository
+
+Once verified be sure to [make a release for the `contrib` repository](https://github.com/open-telemetry/opentelemetry-go-contrib/blob/master/RELEASING.md) that uses this release.
diff --git a/vendor/go.opentelemetry.io/otel/api/global/doc.go b/vendor/go.opentelemetry.io/otel/api/global/doc.go
new file mode 100644
index 0000000..fce69e9
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/global/doc.go
@@ -0,0 +1,16 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package global provides global providers, propagators and more.
+package global // import "go.opentelemetry.io/otel/api/global"
diff --git a/vendor/go.opentelemetry.io/otel/api/global/handler.go b/vendor/go.opentelemetry.io/otel/api/global/handler.go
new file mode 100644
index 0000000..83f3e52
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/global/handler.go
@@ -0,0 +1,91 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package global
+
+import (
+	"log"
+	"os"
+	"sync"
+	"sync/atomic"
+
+	"go.opentelemetry.io/otel"
+)
+
+var (
+	// globalErrorHandler provides an ErrorHandler that can be used
+	// throughout an OpenTelemetry instrumented project. When a user
+	// specified ErrorHandler is registered (`SetErrorHandler`) all calls to
+	// `Handle` and will be delegated to the registered ErrorHandler.
+	globalErrorHandler = &loggingErrorHandler{
+		l: log.New(os.Stderr, "", log.LstdFlags),
+	}
+
+	// delegateErrorHandlerOnce ensures that a user provided ErrorHandler is
+	// only ever registered once.
+	delegateErrorHandlerOnce sync.Once
+
+	// Comiple time check that loggingErrorHandler implements ErrorHandler.
+	_ otel.ErrorHandler = (*loggingErrorHandler)(nil)
+)
+
+// loggingErrorHandler logs all errors to STDERR.
+type loggingErrorHandler struct {
+	delegate atomic.Value
+
+	l *log.Logger
+}
+
+// setDelegate sets the ErrorHandler delegate if one is not already set.
+func (h *loggingErrorHandler) setDelegate(d otel.ErrorHandler) {
+	if h.delegate.Load() != nil {
+		// Delegate already registered
+		return
+	}
+	h.delegate.Store(d)
+}
+
+// Handle implements otel.ErrorHandler.
+func (h *loggingErrorHandler) Handle(err error) {
+	if d := h.delegate.Load(); d != nil {
+		d.(otel.ErrorHandler).Handle(err)
+		return
+	}
+	h.l.Print(err)
+}
+
+// ErrorHandler returns the global ErrorHandler instance. If no ErrorHandler
+// instance has been set (`SetErrorHandler`), the default ErrorHandler which
+// logs errors to STDERR is returned.
+func ErrorHandler() otel.ErrorHandler {
+	return globalErrorHandler
+}
+
+// SetErrorHandler sets the global ErrorHandler to be h.
+func SetErrorHandler(h otel.ErrorHandler) {
+	delegateErrorHandlerOnce.Do(func() {
+		current := ErrorHandler()
+		if current == h {
+			return
+		}
+		if internalHandler, ok := current.(*loggingErrorHandler); ok {
+			internalHandler.setDelegate(h)
+		}
+	})
+}
+
+// Handle is a convience function for ErrorHandler().Handle(err)
+func Handle(err error) {
+	ErrorHandler().Handle(err)
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/global/internal/meter.go b/vendor/go.opentelemetry.io/otel/api/global/internal/meter.go
new file mode 100644
index 0000000..b45f4c9
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/global/internal/meter.go
@@ -0,0 +1,347 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal
+
+import (
+	"context"
+	"sync"
+	"sync/atomic"
+	"unsafe"
+
+	"go.opentelemetry.io/otel/api/metric"
+	"go.opentelemetry.io/otel/api/metric/registry"
+	"go.opentelemetry.io/otel/label"
+)
+
+// This file contains the forwarding implementation of MeterProvider used as
+// the default global instance.  Metric events using instruments provided by
+// this implementation are no-ops until the first Meter implementation is set
+// as the global provider.
+//
+// The implementation here uses Mutexes to maintain a list of active Meters in
+// the MeterProvider and Instruments in each Meter, under the assumption that
+// these interfaces are not performance-critical.
+//
+// We have the invariant that setDelegate() will be called before a new
+// MeterProvider implementation is registered as the global provider.  Mutexes
+// in the MeterProvider and Meters ensure that each instrument has a delegate
+// before the global provider is set.
+//
+// Bound instrument operations are implemented by delegating to the
+// instrument after it is registered, with a sync.Once initializer to
+// protect against races with Release().
+//
+// Metric uniqueness checking is implemented by calling the exported
+// methods of the api/metric/registry package.
+
+type meterKey struct {
+	Name, Version string
+}
+
+type meterProvider struct {
+	delegate metric.MeterProvider
+
+	// lock protects `delegate` and `meters`.
+	lock sync.Mutex
+
+	// meters maintains a unique entry for every named Meter
+	// that has been registered through the global instance.
+	meters map[meterKey]*meterEntry
+}
+
+type meterImpl struct {
+	delegate unsafe.Pointer // (*metric.MeterImpl)
+
+	lock       sync.Mutex
+	syncInsts  []*syncImpl
+	asyncInsts []*asyncImpl
+}
+
+type meterEntry struct {
+	unique metric.MeterImpl
+	impl   meterImpl
+}
+
+type instrument struct {
+	descriptor metric.Descriptor
+}
+
+type syncImpl struct {
+	delegate unsafe.Pointer // (*metric.SyncImpl)
+
+	instrument
+}
+
+type asyncImpl struct {
+	delegate unsafe.Pointer // (*metric.AsyncImpl)
+
+	instrument
+
+	runner metric.AsyncRunner
+}
+
+// SyncImpler is implemented by all of the sync metric
+// instruments.
+type SyncImpler interface {
+	SyncImpl() metric.SyncImpl
+}
+
+// AsyncImpler is implemented by all of the async
+// metric instruments.
+type AsyncImpler interface {
+	AsyncImpl() metric.AsyncImpl
+}
+
+type syncHandle struct {
+	delegate unsafe.Pointer // (*metric.HandleImpl)
+
+	inst   *syncImpl
+	labels []label.KeyValue
+
+	initialize sync.Once
+}
+
+var _ metric.MeterProvider = &meterProvider{}
+var _ metric.MeterImpl = &meterImpl{}
+var _ metric.InstrumentImpl = &syncImpl{}
+var _ metric.BoundSyncImpl = &syncHandle{}
+var _ metric.AsyncImpl = &asyncImpl{}
+
+func (inst *instrument) Descriptor() metric.Descriptor {
+	return inst.descriptor
+}
+
+// MeterProvider interface and delegation
+
+func newMeterProvider() *meterProvider {
+	return &meterProvider{
+		meters: map[meterKey]*meterEntry{},
+	}
+}
+
+func (p *meterProvider) setDelegate(provider metric.MeterProvider) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	p.delegate = provider
+	for key, entry := range p.meters {
+		entry.impl.setDelegate(key.Name, key.Version, provider)
+	}
+	p.meters = nil
+}
+
+func (p *meterProvider) Meter(instrumentationName string, opts ...metric.MeterOption) metric.Meter {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	if p.delegate != nil {
+		return p.delegate.Meter(instrumentationName, opts...)
+	}
+
+	key := meterKey{
+		Name:    instrumentationName,
+		Version: metric.NewMeterConfig(opts...).InstrumentationVersion,
+	}
+	entry, ok := p.meters[key]
+	if !ok {
+		entry = &meterEntry{}
+		entry.unique = registry.NewUniqueInstrumentMeterImpl(&entry.impl)
+		p.meters[key] = entry
+
+	}
+	return metric.WrapMeterImpl(entry.unique, key.Name, metric.WithInstrumentationVersion(key.Version))
+}
+
+// Meter interface and delegation
+
+func (m *meterImpl) setDelegate(name, version string, provider metric.MeterProvider) {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	d := new(metric.MeterImpl)
+	*d = provider.Meter(name, metric.WithInstrumentationVersion(version)).MeterImpl()
+	m.delegate = unsafe.Pointer(d)
+
+	for _, inst := range m.syncInsts {
+		inst.setDelegate(*d)
+	}
+	m.syncInsts = nil
+	for _, obs := range m.asyncInsts {
+		obs.setDelegate(*d)
+	}
+	m.asyncInsts = nil
+}
+
+func (m *meterImpl) NewSyncInstrument(desc metric.Descriptor) (metric.SyncImpl, error) {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	if meterPtr := (*metric.MeterImpl)(atomic.LoadPointer(&m.delegate)); meterPtr != nil {
+		return (*meterPtr).NewSyncInstrument(desc)
+	}
+
+	inst := &syncImpl{
+		instrument: instrument{
+			descriptor: desc,
+		},
+	}
+	m.syncInsts = append(m.syncInsts, inst)
+	return inst, nil
+}
+
+// Synchronous delegation
+
+func (inst *syncImpl) setDelegate(d metric.MeterImpl) {
+	implPtr := new(metric.SyncImpl)
+
+	var err error
+	*implPtr, err = d.NewSyncInstrument(inst.descriptor)
+
+	if err != nil {
+		// TODO: There is no standard way to deliver this error to the user.
+		// See https://github.com/open-telemetry/opentelemetry-go/issues/514
+		// Note that the default SDK will not generate any errors yet, this is
+		// only for added safety.
+		panic(err)
+	}
+
+	atomic.StorePointer(&inst.delegate, unsafe.Pointer(implPtr))
+}
+
+func (inst *syncImpl) Implementation() interface{} {
+	if implPtr := (*metric.SyncImpl)(atomic.LoadPointer(&inst.delegate)); implPtr != nil {
+		return (*implPtr).Implementation()
+	}
+	return inst
+}
+
+func (inst *syncImpl) Bind(labels []label.KeyValue) metric.BoundSyncImpl {
+	if implPtr := (*metric.SyncImpl)(atomic.LoadPointer(&inst.delegate)); implPtr != nil {
+		return (*implPtr).Bind(labels)
+	}
+	return &syncHandle{
+		inst:   inst,
+		labels: labels,
+	}
+}
+
+func (bound *syncHandle) Unbind() {
+	bound.initialize.Do(func() {})
+
+	implPtr := (*metric.BoundSyncImpl)(atomic.LoadPointer(&bound.delegate))
+
+	if implPtr == nil {
+		return
+	}
+
+	(*implPtr).Unbind()
+}
+
+// Async delegation
+
+func (m *meterImpl) NewAsyncInstrument(
+	desc metric.Descriptor,
+	runner metric.AsyncRunner,
+) (metric.AsyncImpl, error) {
+
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	if meterPtr := (*metric.MeterImpl)(atomic.LoadPointer(&m.delegate)); meterPtr != nil {
+		return (*meterPtr).NewAsyncInstrument(desc, runner)
+	}
+
+	inst := &asyncImpl{
+		instrument: instrument{
+			descriptor: desc,
+		},
+		runner: runner,
+	}
+	m.asyncInsts = append(m.asyncInsts, inst)
+	return inst, nil
+}
+
+func (obs *asyncImpl) Implementation() interface{} {
+	if implPtr := (*metric.AsyncImpl)(atomic.LoadPointer(&obs.delegate)); implPtr != nil {
+		return (*implPtr).Implementation()
+	}
+	return obs
+}
+
+func (obs *asyncImpl) setDelegate(d metric.MeterImpl) {
+	implPtr := new(metric.AsyncImpl)
+
+	var err error
+	*implPtr, err = d.NewAsyncInstrument(obs.descriptor, obs.runner)
+
+	if err != nil {
+		// TODO: There is no standard way to deliver this error to the user.
+		// See https://github.com/open-telemetry/opentelemetry-go/issues/514
+		// Note that the default SDK will not generate any errors yet, this is
+		// only for added safety.
+		panic(err)
+	}
+
+	atomic.StorePointer(&obs.delegate, unsafe.Pointer(implPtr))
+}
+
+// Metric updates
+
+func (m *meterImpl) RecordBatch(ctx context.Context, labels []label.KeyValue, measurements ...metric.Measurement) {
+	if delegatePtr := (*metric.MeterImpl)(atomic.LoadPointer(&m.delegate)); delegatePtr != nil {
+		(*delegatePtr).RecordBatch(ctx, labels, measurements...)
+	}
+}
+
+func (inst *syncImpl) RecordOne(ctx context.Context, number metric.Number, labels []label.KeyValue) {
+	if instPtr := (*metric.SyncImpl)(atomic.LoadPointer(&inst.delegate)); instPtr != nil {
+		(*instPtr).RecordOne(ctx, number, labels)
+	}
+}
+
+// Bound instrument initialization
+
+func (bound *syncHandle) RecordOne(ctx context.Context, number metric.Number) {
+	instPtr := (*metric.SyncImpl)(atomic.LoadPointer(&bound.inst.delegate))
+	if instPtr == nil {
+		return
+	}
+	var implPtr *metric.BoundSyncImpl
+	bound.initialize.Do(func() {
+		implPtr = new(metric.BoundSyncImpl)
+		*implPtr = (*instPtr).Bind(bound.labels)
+		atomic.StorePointer(&bound.delegate, unsafe.Pointer(implPtr))
+	})
+	if implPtr == nil {
+		implPtr = (*metric.BoundSyncImpl)(atomic.LoadPointer(&bound.delegate))
+	}
+	// This may still be nil if instrument was created and bound
+	// without a delegate, then the instrument was set to have a
+	// delegate and unbound.
+	if implPtr == nil {
+		return
+	}
+	(*implPtr).RecordOne(ctx, number)
+}
+
+func AtomicFieldOffsets() map[string]uintptr {
+	return map[string]uintptr{
+		"meterProvider.delegate": unsafe.Offsetof(meterProvider{}.delegate),
+		"meterImpl.delegate":     unsafe.Offsetof(meterImpl{}.delegate),
+		"syncImpl.delegate":      unsafe.Offsetof(syncImpl{}.delegate),
+		"asyncImpl.delegate":     unsafe.Offsetof(asyncImpl{}.delegate),
+		"syncHandle.delegate":    unsafe.Offsetof(syncHandle{}.delegate),
+	}
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/global/internal/state.go b/vendor/go.opentelemetry.io/otel/api/global/internal/state.go
new file mode 100644
index 0000000..ecdfd75
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/global/internal/state.go
@@ -0,0 +1,134 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal
+
+import (
+	"sync"
+	"sync/atomic"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/api/metric"
+	"go.opentelemetry.io/otel/api/trace"
+)
+
+type (
+	tracerProviderHolder struct {
+		tp trace.TracerProvider
+	}
+
+	meterProviderHolder struct {
+		mp metric.MeterProvider
+	}
+
+	propagatorsHolder struct {
+		tm otel.TextMapPropagator
+	}
+)
+
+var (
+	globalTracer      = defaultTracerValue()
+	globalMeter       = defaultMeterValue()
+	globalPropagators = defaultPropagatorsValue()
+
+	delegateMeterOnce sync.Once
+	delegateTraceOnce sync.Once
+)
+
+// TracerProvider is the internal implementation for global.TracerProvider.
+func TracerProvider() trace.TracerProvider {
+	return globalTracer.Load().(tracerProviderHolder).tp
+}
+
+// SetTracerProvider is the internal implementation for global.SetTracerProvider.
+func SetTracerProvider(tp trace.TracerProvider) {
+	delegateTraceOnce.Do(func() {
+		current := TracerProvider()
+		if current == tp {
+			// Setting the provider to the prior default is nonsense, panic.
+			// Panic is acceptable because we are likely still early in the
+			// process lifetime.
+			panic("invalid TracerProvider, the global instance cannot be reinstalled")
+		} else if def, ok := current.(*tracerProvider); ok {
+			def.setDelegate(tp)
+		}
+
+	})
+	globalTracer.Store(tracerProviderHolder{tp: tp})
+}
+
+// MeterProvider is the internal implementation for global.MeterProvider.
+func MeterProvider() metric.MeterProvider {
+	return globalMeter.Load().(meterProviderHolder).mp
+}
+
+// SetMeterProvider is the internal implementation for global.SetMeterProvider.
+func SetMeterProvider(mp metric.MeterProvider) {
+	delegateMeterOnce.Do(func() {
+		current := MeterProvider()
+
+		if current == mp {
+			// Setting the provider to the prior default is nonsense, panic.
+			// Panic is acceptable because we are likely still early in the
+			// process lifetime.
+			panic("invalid MeterProvider, the global instance cannot be reinstalled")
+		} else if def, ok := current.(*meterProvider); ok {
+			def.setDelegate(mp)
+		}
+	})
+	globalMeter.Store(meterProviderHolder{mp: mp})
+}
+
+// TextMapPropagator is the internal implementation for global.TextMapPropagator.
+func TextMapPropagator() otel.TextMapPropagator {
+	return globalPropagators.Load().(propagatorsHolder).tm
+}
+
+// SetTextMapPropagator is the internal implementation for global.SetTextMapPropagator.
+func SetTextMapPropagator(p otel.TextMapPropagator) {
+	globalPropagators.Store(propagatorsHolder{tm: p})
+}
+
+func defaultTracerValue() *atomic.Value {
+	v := &atomic.Value{}
+	v.Store(tracerProviderHolder{tp: &tracerProvider{}})
+	return v
+}
+
+func defaultMeterValue() *atomic.Value {
+	v := &atomic.Value{}
+	v.Store(meterProviderHolder{mp: newMeterProvider()})
+	return v
+}
+
+func defaultPropagatorsValue() *atomic.Value {
+	v := &atomic.Value{}
+	v.Store(propagatorsHolder{tm: getDefaultTextMapPropagator()})
+	return v
+}
+
+// getDefaultTextMapPropagator returns the default TextMapPropagator,
+// configured with W3C trace and baggage propagation.
+func getDefaultTextMapPropagator() otel.TextMapPropagator {
+	return otel.NewCompositeTextMapPropagator()
+}
+
+// ResetForTest restores the initial global state, for testing purposes.
+func ResetForTest() {
+	globalTracer = defaultTracerValue()
+	globalMeter = defaultMeterValue()
+	globalPropagators = defaultPropagatorsValue()
+	delegateMeterOnce = sync.Once{}
+	delegateTraceOnce = sync.Once{}
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/global/internal/trace.go b/vendor/go.opentelemetry.io/otel/api/global/internal/trace.go
new file mode 100644
index 0000000..bcd1461
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/global/internal/trace.go
@@ -0,0 +1,128 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal
+
+/*
+This file contains the forwarding implementation of the TracerProvider used as
+the default global instance. Prior to initialization of an SDK, Tracers
+returned by the global TracerProvider will provide no-op functionality. This
+means that all Span created prior to initialization are no-op Spans.
+
+Once an SDK has been initialized, all provided no-op Tracers are swapped for
+Tracers provided by the SDK defined TracerProvider. However, any Span started
+prior to this initialization does not change its behavior. Meaning, the Span
+remains a no-op Span.
+
+The implementation to track and swap Tracers locks all new Tracer creation
+until the swap is complete. This assumes that this operation is not
+performance-critical. If that assumption is incorrect, be sure to configure an
+SDK prior to any Tracer creation.
+*/
+
+import (
+	"context"
+	"sync"
+
+	"go.opentelemetry.io/otel/api/trace"
+	"go.opentelemetry.io/otel/internal/trace/noop"
+)
+
+// tracerProvider is a placeholder for a configured SDK TracerProvider.
+//
+// All TracerProvider functionality is forwarded to a delegate once
+// configured.
+type tracerProvider struct {
+	mtx     sync.Mutex
+	tracers []*tracer
+
+	delegate trace.TracerProvider
+}
+
+// Compile-time guarantee that tracerProvider implements the TracerProvider
+// interface.
+var _ trace.TracerProvider = &tracerProvider{}
+
+// setDelegate configures p to delegate all TracerProvider functionality to
+// provider.
+//
+// All Tracers provided prior to this function call are switched out to be
+// Tracers provided by provider.
+//
+// Delegation only happens on the first call to this method. All subsequent
+// calls result in no delegation changes.
+func (p *tracerProvider) setDelegate(provider trace.TracerProvider) {
+	if p.delegate != nil {
+		return
+	}
+
+	p.mtx.Lock()
+	defer p.mtx.Unlock()
+
+	p.delegate = provider
+	for _, t := range p.tracers {
+		t.setDelegate(provider)
+	}
+
+	p.tracers = nil
+}
+
+// Tracer implements TracerProvider.
+func (p *tracerProvider) Tracer(name string, opts ...trace.TracerOption) trace.Tracer {
+	p.mtx.Lock()
+	defer p.mtx.Unlock()
+
+	if p.delegate != nil {
+		return p.delegate.Tracer(name)
+	}
+
+	t := &tracer{name: name, opts: opts}
+	p.tracers = append(p.tracers, t)
+	return t
+}
+
+// tracer is a placeholder for a trace.Tracer.
+//
+// All Tracer functionality is forwarded to a delegate once configured.
+// Otherwise, all functionality is forwarded to a NoopTracer.
+type tracer struct {
+	once sync.Once
+	name string
+	opts []trace.TracerOption
+
+	delegate trace.Tracer
+}
+
+// Compile-time guarantee that tracer implements the trace.Tracer interface.
+var _ trace.Tracer = &tracer{}
+
+// setDelegate configures t to delegate all Tracer functionality to Tracers
+// created by provider.
+//
+// All subsequent calls to the Tracer methods will be passed to the delegate.
+//
+// Delegation only happens on the first call to this method. All subsequent
+// calls result in no delegation changes.
+func (t *tracer) setDelegate(provider trace.TracerProvider) {
+	t.once.Do(func() { t.delegate = provider.Tracer(t.name, t.opts...) })
+}
+
+// Start implements trace.Tracer by forwarding the call to t.delegate if
+// set, otherwise it forwards the call to a NoopTracer.
+func (t *tracer) Start(ctx context.Context, name string, opts ...trace.SpanOption) (context.Context, trace.Span) {
+	if t.delegate != nil {
+		return t.delegate.Start(ctx, name, opts...)
+	}
+	return noop.Tracer.Start(ctx, name, opts...)
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/global/metric.go b/vendor/go.opentelemetry.io/otel/api/global/metric.go
new file mode 100644
index 0000000..f1695bb
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/global/metric.go
@@ -0,0 +1,49 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package global
+
+import (
+	"go.opentelemetry.io/otel/api/global/internal"
+	"go.opentelemetry.io/otel/api/metric"
+)
+
+// Meter creates an implementation of the Meter interface from the global
+// MeterProvider. The instrumentationName must be the name of the library
+// providing instrumentation. This name may be the same as the instrumented
+// code only if that code provides built-in instrumentation. If the
+// instrumentationName is empty, then a implementation defined default name
+// will be used instead.
+//
+// This is short for MeterProvider().Meter(name)
+func Meter(instrumentationName string, opts ...metric.MeterOption) metric.Meter {
+	return MeterProvider().Meter(instrumentationName, opts...)
+}
+
+// MeterProvider returns the registered global meter provider.  If
+// none is registered then a default meter provider is returned that
+// forwards the Meter interface to the first registered Meter.
+//
+// Use the meter provider to create a named meter. E.g.
+//     meter := global.MeterProvider().Meter("example.com/foo")
+// or
+//     meter := global.Meter("example.com/foo")
+func MeterProvider() metric.MeterProvider {
+	return internal.MeterProvider()
+}
+
+// SetMeterProvider registers `mp` as the global meter provider.
+func SetMeterProvider(mp metric.MeterProvider) {
+	internal.SetMeterProvider(mp)
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/global/propagation.go b/vendor/go.opentelemetry.io/otel/api/global/propagation.go
new file mode 100644
index 0000000..c5f4c2b
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/global/propagation.go
@@ -0,0 +1,31 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package global
+
+import (
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/api/global/internal"
+)
+
+// TextMapPropagator returns the global TextMapPropagator. If none has been
+// set, a No-Op TextMapPropagator is returned.
+func TextMapPropagator() otel.TextMapPropagator {
+	return internal.TextMapPropagator()
+}
+
+// SetTextMapPropagator sets propagator as the global TSetTextMapPropagator.
+func SetTextMapPropagator(propagator otel.TextMapPropagator) {
+	internal.SetTextMapPropagator(propagator)
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/global/trace.go b/vendor/go.opentelemetry.io/otel/api/global/trace.go
new file mode 100644
index 0000000..49a7543
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/global/trace.go
@@ -0,0 +1,44 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package global
+
+import (
+	"go.opentelemetry.io/otel/api/global/internal"
+	"go.opentelemetry.io/otel/api/trace"
+)
+
+// Tracer creates a named tracer that implements Tracer interface.
+// If the name is an empty string then provider uses default name.
+//
+// This is short for TracerProvider().Tracer(name)
+func Tracer(name string) trace.Tracer {
+	return TracerProvider().Tracer(name)
+}
+
+// TracerProvider returns the registered global trace provider.
+// If none is registered then an instance of NoopTracerProvider is returned.
+//
+// Use the trace provider to create a named tracer. E.g.
+//     tracer := global.TracerProvider().Tracer("example.com/foo")
+// or
+//     tracer := global.Tracer("example.com/foo")
+func TracerProvider() trace.TracerProvider {
+	return internal.TracerProvider()
+}
+
+// SetTracerProvider registers `tp` as the global trace provider.
+func SetTracerProvider(tp trace.TracerProvider) {
+	internal.SetTracerProvider(tp)
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/async.go b/vendor/go.opentelemetry.io/otel/api/metric/async.go
new file mode 100644
index 0000000..d0d488d
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/async.go
@@ -0,0 +1,217 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/label"
+)
+
+// The file is organized as follows:
+//
+//  - Observation type
+//  - Three kinds of Observer callback (int64, float64, batch)
+//  - Three kinds of Observer result (int64, float64, batch)
+//  - Three kinds of Observe() function (int64, float64, batch)
+//  - Three kinds of AsyncRunner interface (abstract, single, batch)
+//  - Two kinds of Observer constructor (int64, float64)
+//  - Two kinds of Observation() function (int64, float64)
+//  - Various internals
+
+// Observation is used for reporting an asynchronous  batch of metric
+// values. Instances of this type should be created by asynchronous
+// instruments (e.g., Int64ValueObserver.Observation()).
+type Observation struct {
+	// number needs to be aligned for 64-bit atomic operations.
+	number     Number
+	instrument AsyncImpl
+}
+
+// Int64ObserverFunc is a type of callback that integral
+// observers run.
+type Int64ObserverFunc func(context.Context, Int64ObserverResult)
+
+// Float64ObserverFunc is a type of callback that floating point
+// observers run.
+type Float64ObserverFunc func(context.Context, Float64ObserverResult)
+
+// BatchObserverFunc is a callback argument for use with any
+// Observer instrument that will be reported as a batch of
+// observations.
+type BatchObserverFunc func(context.Context, BatchObserverResult)
+
+// Int64ObserverResult is passed to an observer callback to capture
+// observations for one asynchronous integer metric instrument.
+type Int64ObserverResult struct {
+	instrument AsyncImpl
+	function   func([]label.KeyValue, ...Observation)
+}
+
+// Float64ObserverResult is passed to an observer callback to capture
+// observations for one asynchronous floating point metric instrument.
+type Float64ObserverResult struct {
+	instrument AsyncImpl
+	function   func([]label.KeyValue, ...Observation)
+}
+
+// BatchObserverResult is passed to a batch observer callback to
+// capture observations for multiple asynchronous instruments.
+type BatchObserverResult struct {
+	function func([]label.KeyValue, ...Observation)
+}
+
+// Observe captures a single integer value from the associated
+// instrument callback, with the given labels.
+func (ir Int64ObserverResult) Observe(value int64, labels ...label.KeyValue) {
+	ir.function(labels, Observation{
+		instrument: ir.instrument,
+		number:     NewInt64Number(value),
+	})
+}
+
+// Observe captures a single floating point value from the associated
+// instrument callback, with the given labels.
+func (fr Float64ObserverResult) Observe(value float64, labels ...label.KeyValue) {
+	fr.function(labels, Observation{
+		instrument: fr.instrument,
+		number:     NewFloat64Number(value),
+	})
+}
+
+// Observe captures a multiple observations from the associated batch
+// instrument callback, with the given labels.
+func (br BatchObserverResult) Observe(labels []label.KeyValue, obs ...Observation) {
+	br.function(labels, obs...)
+}
+
+// AsyncRunner is expected to convert into an AsyncSingleRunner or an
+// AsyncBatchRunner.  SDKs will encounter an error if the AsyncRunner
+// does not satisfy one of these interfaces.
+type AsyncRunner interface {
+	// AnyRunner() is a non-exported method with no functional use
+	// other than to make this a non-empty interface.
+	AnyRunner()
+}
+
+// AsyncSingleRunner is an interface implemented by single-observer
+// callbacks.
+type AsyncSingleRunner interface {
+	// Run accepts a single instrument and function for capturing
+	// observations of that instrument.  Each call to the function
+	// receives one captured observation.  (The function accepts
+	// multiple observations so the same implementation can be
+	// used for batch runners.)
+	Run(ctx context.Context, single AsyncImpl, capture func([]label.KeyValue, ...Observation))
+
+	AsyncRunner
+}
+
+// AsyncBatchRunner is an interface implemented by batch-observer
+// callbacks.
+type AsyncBatchRunner interface {
+	// Run accepts a function for capturing observations of
+	// multiple instruments.
+	Run(ctx context.Context, capture func([]label.KeyValue, ...Observation))
+
+	AsyncRunner
+}
+
+var _ AsyncSingleRunner = (*Int64ObserverFunc)(nil)
+var _ AsyncSingleRunner = (*Float64ObserverFunc)(nil)
+var _ AsyncBatchRunner = (*BatchObserverFunc)(nil)
+
+// newInt64AsyncRunner returns a single-observer callback for integer Observer instruments.
+func newInt64AsyncRunner(c Int64ObserverFunc) AsyncSingleRunner {
+	return &c
+}
+
+// newFloat64AsyncRunner returns a single-observer callback for floating point Observer instruments.
+func newFloat64AsyncRunner(c Float64ObserverFunc) AsyncSingleRunner {
+	return &c
+}
+
+// newBatchAsyncRunner returns a batch-observer callback use with multiple Observer instruments.
+func newBatchAsyncRunner(c BatchObserverFunc) AsyncBatchRunner {
+	return &c
+}
+
+// AnyRunner implements AsyncRunner.
+func (*Int64ObserverFunc) AnyRunner() {}
+
+// AnyRunner implements AsyncRunner.
+func (*Float64ObserverFunc) AnyRunner() {}
+
+// AnyRunner implements AsyncRunner.
+func (*BatchObserverFunc) AnyRunner() {}
+
+// Run implements AsyncSingleRunner.
+func (i *Int64ObserverFunc) Run(ctx context.Context, impl AsyncImpl, function func([]label.KeyValue, ...Observation)) {
+	(*i)(ctx, Int64ObserverResult{
+		instrument: impl,
+		function:   function,
+	})
+}
+
+// Run implements AsyncSingleRunner.
+func (f *Float64ObserverFunc) Run(ctx context.Context, impl AsyncImpl, function func([]label.KeyValue, ...Observation)) {
+	(*f)(ctx, Float64ObserverResult{
+		instrument: impl,
+		function:   function,
+	})
+}
+
+// Run implements AsyncBatchRunner.
+func (b *BatchObserverFunc) Run(ctx context.Context, function func([]label.KeyValue, ...Observation)) {
+	(*b)(ctx, BatchObserverResult{
+		function: function,
+	})
+}
+
+// wrapInt64ValueObserverInstrument converts an AsyncImpl into Int64ValueObserver.
+func wrapInt64ValueObserverInstrument(asyncInst AsyncImpl, err error) (Int64ValueObserver, error) {
+	common, err := checkNewAsync(asyncInst, err)
+	return Int64ValueObserver{asyncInstrument: common}, err
+}
+
+// wrapFloat64ValueObserverInstrument converts an AsyncImpl into Float64ValueObserver.
+func wrapFloat64ValueObserverInstrument(asyncInst AsyncImpl, err error) (Float64ValueObserver, error) {
+	common, err := checkNewAsync(asyncInst, err)
+	return Float64ValueObserver{asyncInstrument: common}, err
+}
+
+// wrapInt64SumObserverInstrument converts an AsyncImpl into Int64SumObserver.
+func wrapInt64SumObserverInstrument(asyncInst AsyncImpl, err error) (Int64SumObserver, error) {
+	common, err := checkNewAsync(asyncInst, err)
+	return Int64SumObserver{asyncInstrument: common}, err
+}
+
+// wrapFloat64SumObserverInstrument converts an AsyncImpl into Float64SumObserver.
+func wrapFloat64SumObserverInstrument(asyncInst AsyncImpl, err error) (Float64SumObserver, error) {
+	common, err := checkNewAsync(asyncInst, err)
+	return Float64SumObserver{asyncInstrument: common}, err
+}
+
+// wrapInt64UpDownSumObserverInstrument converts an AsyncImpl into Int64UpDownSumObserver.
+func wrapInt64UpDownSumObserverInstrument(asyncInst AsyncImpl, err error) (Int64UpDownSumObserver, error) {
+	common, err := checkNewAsync(asyncInst, err)
+	return Int64UpDownSumObserver{asyncInstrument: common}, err
+}
+
+// wrapFloat64UpDownSumObserverInstrument converts an AsyncImpl into Float64UpDownSumObserver.
+func wrapFloat64UpDownSumObserverInstrument(asyncInst AsyncImpl, err error) (Float64UpDownSumObserver, error) {
+	common, err := checkNewAsync(asyncInst, err)
+	return Float64UpDownSumObserver{asyncInstrument: common}, err
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/config.go b/vendor/go.opentelemetry.io/otel/api/metric/config.go
new file mode 100644
index 0000000..3cd8fe8
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/config.go
@@ -0,0 +1,125 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import "go.opentelemetry.io/otel/unit"
+
+// InstrumentConfig contains options for instrument descriptors.
+type InstrumentConfig struct {
+	// Description describes the instrument in human-readable terms.
+	Description string
+	// Unit describes the measurement unit for a instrument.
+	Unit unit.Unit
+	// InstrumentationName is the name of the library providing
+	// instrumentation.
+	InstrumentationName string
+	// InstrumentationVersion is the version of the library providing
+	// instrumentation.
+	InstrumentationVersion string
+}
+
+// InstrumentOption is an interface for applying instrument options.
+type InstrumentOption interface {
+	// ApplyMeter is used to set a InstrumentOption value of a
+	// InstrumentConfig.
+	ApplyInstrument(*InstrumentConfig)
+}
+
+// NewInstrumentConfig creates a new InstrumentConfig
+// and applies all the given options.
+func NewInstrumentConfig(opts ...InstrumentOption) InstrumentConfig {
+	var config InstrumentConfig
+	for _, o := range opts {
+		o.ApplyInstrument(&config)
+	}
+	return config
+}
+
+// WithDescription applies provided description.
+func WithDescription(desc string) InstrumentOption {
+	return descriptionOption(desc)
+}
+
+type descriptionOption string
+
+func (d descriptionOption) ApplyInstrument(config *InstrumentConfig) {
+	config.Description = string(d)
+}
+
+// WithUnit applies provided unit.
+func WithUnit(unit unit.Unit) InstrumentOption {
+	return unitOption(unit)
+}
+
+type unitOption unit.Unit
+
+func (u unitOption) ApplyInstrument(config *InstrumentConfig) {
+	config.Unit = unit.Unit(u)
+}
+
+// WithInstrumentationName sets the instrumentation name.
+func WithInstrumentationName(name string) InstrumentOption {
+	return instrumentationNameOption(name)
+}
+
+type instrumentationNameOption string
+
+func (i instrumentationNameOption) ApplyInstrument(config *InstrumentConfig) {
+	config.InstrumentationName = string(i)
+}
+
+// MeterConfig contains options for Meters.
+type MeterConfig struct {
+	// InstrumentationVersion is the version of the library providing
+	// instrumentation.
+	InstrumentationVersion string
+}
+
+// MeterOption is an interface for applying Meter options.
+type MeterOption interface {
+	// ApplyMeter is used to set a MeterOption value of a MeterConfig.
+	ApplyMeter(*MeterConfig)
+}
+
+// NewMeterConfig creates a new MeterConfig and applies
+// all the given options.
+func NewMeterConfig(opts ...MeterOption) MeterConfig {
+	var config MeterConfig
+	for _, o := range opts {
+		o.ApplyMeter(&config)
+	}
+	return config
+}
+
+// Option is an interface for applying Instrument or Meter options.
+type Option interface {
+	InstrumentOption
+	MeterOption
+}
+
+// WithInstrumentationVersion sets the instrumentation version.
+func WithInstrumentationVersion(version string) Option {
+	return instrumentationVersionOption(version)
+}
+
+type instrumentationVersionOption string
+
+func (i instrumentationVersionOption) ApplyMeter(config *MeterConfig) {
+	config.InstrumentationVersion = string(i)
+}
+
+func (i instrumentationVersionOption) ApplyInstrument(config *InstrumentConfig) {
+	config.InstrumentationVersion = string(i)
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/counter.go b/vendor/go.opentelemetry.io/otel/api/metric/counter.go
new file mode 100644
index 0000000..c03421d
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/counter.go
@@ -0,0 +1,95 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/label"
+)
+
+// Float64Counter is a metric that accumulates float64 values.
+type Float64Counter struct {
+	syncInstrument
+}
+
+// Int64Counter is a metric that accumulates int64 values.
+type Int64Counter struct {
+	syncInstrument
+}
+
+// BoundFloat64Counter is a bound instrument for Float64Counter.
+//
+// It inherits the Unbind function from syncBoundInstrument.
+type BoundFloat64Counter struct {
+	syncBoundInstrument
+}
+
+// BoundInt64Counter is a boundInstrument for Int64Counter.
+//
+// It inherits the Unbind function from syncBoundInstrument.
+type BoundInt64Counter struct {
+	syncBoundInstrument
+}
+
+// Bind creates a bound instrument for this counter. The labels are
+// associated with values recorded via subsequent calls to Record.
+func (c Float64Counter) Bind(labels ...label.KeyValue) (h BoundFloat64Counter) {
+	h.syncBoundInstrument = c.bind(labels)
+	return
+}
+
+// Bind creates a bound instrument for this counter. The labels are
+// associated with values recorded via subsequent calls to Record.
+func (c Int64Counter) Bind(labels ...label.KeyValue) (h BoundInt64Counter) {
+	h.syncBoundInstrument = c.bind(labels)
+	return
+}
+
+// Measurement creates a Measurement object to use with batch
+// recording.
+func (c Float64Counter) Measurement(value float64) Measurement {
+	return c.float64Measurement(value)
+}
+
+// Measurement creates a Measurement object to use with batch
+// recording.
+func (c Int64Counter) Measurement(value int64) Measurement {
+	return c.int64Measurement(value)
+}
+
+// Add adds the value to the counter's sum. The labels should contain
+// the keys and values to be associated with this value.
+func (c Float64Counter) Add(ctx context.Context, value float64, labels ...label.KeyValue) {
+	c.directRecord(ctx, NewFloat64Number(value), labels)
+}
+
+// Add adds the value to the counter's sum. The labels should contain
+// the keys and values to be associated with this value.
+func (c Int64Counter) Add(ctx context.Context, value int64, labels ...label.KeyValue) {
+	c.directRecord(ctx, NewInt64Number(value), labels)
+}
+
+// Add adds the value to the counter's sum using the labels
+// previously bound to this counter via Bind()
+func (b BoundFloat64Counter) Add(ctx context.Context, value float64) {
+	b.directRecord(ctx, NewFloat64Number(value))
+}
+
+// Add adds the value to the counter's sum using the labels
+// previously bound to this counter via Bind()
+func (b BoundInt64Counter) Add(ctx context.Context, value int64) {
+	b.directRecord(ctx, NewInt64Number(value))
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/descriptor.go b/vendor/go.opentelemetry.io/otel/api/metric/descriptor.go
new file mode 100644
index 0000000..3af55e5
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/descriptor.go
@@ -0,0 +1,77 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import "go.opentelemetry.io/otel/unit"
+
+// Descriptor contains all the settings that describe an instrument,
+// including its name, metric kind, number kind, and the configurable
+// options.
+type Descriptor struct {
+	name       string
+	kind       Kind
+	numberKind NumberKind
+	config     InstrumentConfig
+}
+
+// NewDescriptor returns a Descriptor with the given contents.
+func NewDescriptor(name string, mkind Kind, nkind NumberKind, opts ...InstrumentOption) Descriptor {
+	return Descriptor{
+		name:       name,
+		kind:       mkind,
+		numberKind: nkind,
+		config:     NewInstrumentConfig(opts...),
+	}
+}
+
+// Name returns the metric instrument's name.
+func (d Descriptor) Name() string {
+	return d.name
+}
+
+// MetricKind returns the specific kind of instrument.
+func (d Descriptor) MetricKind() Kind {
+	return d.kind
+}
+
+// Description provides a human-readable description of the metric
+// instrument.
+func (d Descriptor) Description() string {
+	return d.config.Description
+}
+
+// Unit describes the units of the metric instrument.  Unitless
+// metrics return the empty string.
+func (d Descriptor) Unit() unit.Unit {
+	return d.config.Unit
+}
+
+// NumberKind returns whether this instrument is declared over int64,
+// float64, or uint64 values.
+func (d Descriptor) NumberKind() NumberKind {
+	return d.numberKind
+}
+
+// InstrumentationName returns the name of the library that provided
+// instrumentation for this instrument.
+func (d Descriptor) InstrumentationName() string {
+	return d.config.InstrumentationName
+}
+
+// InstrumentationVersion returns the version of the library that provided
+// instrumentation for this instrument.
+func (d Descriptor) InstrumentationVersion() string {
+	return d.config.InstrumentationVersion
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/doc.go b/vendor/go.opentelemetry.io/otel/api/metric/doc.go
new file mode 100644
index 0000000..48a59c5
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/doc.go
@@ -0,0 +1,50 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package metric provides support for reporting measurements using instruments.
+//
+// Instruments are categorized as below:
+//
+// Synchronous instruments are called by the user with a Context.
+// Asynchronous instruments are called by the SDK during collection.
+//
+// Additive instruments are semantically intended for capturing a sum.
+// Non-additive instruments are intended for capturing a distribution.
+//
+// Additive instruments may be monotonic, in which case they are
+// non-descreasing and naturally define a rate.
+//
+// The synchronous instrument names are:
+//
+//   Counter:           additive, monotonic
+//   UpDownCounter:     additive
+//   ValueRecorder:     non-additive
+//
+// and the asynchronous instruments are:
+//
+//   SumObserver:       additive, monotonic
+//   UpDownSumObserver: additive
+//   ValueObserver:     non-additive
+//
+// All instruments are provided with support for either float64 or
+// int64 input values.
+//
+// The Meter interface supports allocating new instruments as well as
+// interfaces for recording batches of synchronous measurements or
+// asynchronous observations.  To obtain a Meter, use a MeterProvider.
+//
+// The MeterProvider interface supports obtaining a named Meter interface. To
+// obtain a MeterProvider implementation, initialize and configure any
+// compatible SDK.
+package metric // import "go.opentelemetry.io/otel/api/metric"
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/kind.go b/vendor/go.opentelemetry.io/otel/api/metric/kind.go
new file mode 100644
index 0000000..9d4b453
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/kind.go
@@ -0,0 +1,79 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:generate stringer -type=Kind
+
+package metric
+
+// Kind describes the kind of instrument.
+type Kind int8
+
+const (
+	// ValueRecorderKind indicates a ValueRecorder instrument.
+	ValueRecorderKind Kind = iota
+	// ValueObserverKind indicates an ValueObserver instrument.
+	ValueObserverKind
+
+	// CounterKind indicates a Counter instrument.
+	CounterKind
+	// UpDownCounterKind indicates a UpDownCounter instrument.
+	UpDownCounterKind
+
+	// SumObserverKind indicates a SumObserver instrument.
+	SumObserverKind
+	// UpDownSumObserverKind indicates a UpDownSumObserver instrument.
+	UpDownSumObserverKind
+)
+
+// Synchronous returns whether this is a synchronous kind of instrument.
+func (k Kind) Synchronous() bool {
+	switch k {
+	case CounterKind, UpDownCounterKind, ValueRecorderKind:
+		return true
+	}
+	return false
+}
+
+// Asynchronous returns whether this is an asynchronous kind of instrument.
+func (k Kind) Asynchronous() bool {
+	return !k.Synchronous()
+}
+
+// Adding returns whether this kind of instrument adds its inputs (as opposed to Grouping).
+func (k Kind) Adding() bool {
+	switch k {
+	case CounterKind, UpDownCounterKind, SumObserverKind, UpDownSumObserverKind:
+		return true
+	}
+	return false
+}
+
+// Adding returns whether this kind of instrument groups its inputs (as opposed to Adding).
+func (k Kind) Grouping() bool {
+	return !k.Adding()
+}
+
+// Monotonic returns whether this kind of instrument exposes a non-decreasing sum.
+func (k Kind) Monotonic() bool {
+	switch k {
+	case CounterKind, SumObserverKind:
+		return true
+	}
+	return false
+}
+
+// Cumulative returns whether this kind of instrument receives precomputed sums.
+func (k Kind) PrecomputedSum() bool {
+	return k.Adding() && k.Asynchronous()
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/kind_string.go b/vendor/go.opentelemetry.io/otel/api/metric/kind_string.go
new file mode 100644
index 0000000..eb1a0d5
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/kind_string.go
@@ -0,0 +1,28 @@
+// Code generated by "stringer -type=Kind"; DO NOT EDIT.
+
+package metric
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[ValueRecorderKind-0]
+	_ = x[ValueObserverKind-1]
+	_ = x[CounterKind-2]
+	_ = x[UpDownCounterKind-3]
+	_ = x[SumObserverKind-4]
+	_ = x[UpDownSumObserverKind-5]
+}
+
+const _Kind_name = "ValueRecorderKindValueObserverKindCounterKindUpDownCounterKindSumObserverKindUpDownSumObserverKind"
+
+var _Kind_index = [...]uint8{0, 17, 34, 45, 62, 77, 98}
+
+func (i Kind) String() string {
+	if i < 0 || i >= Kind(len(_Kind_index)-1) {
+		return "Kind(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _Kind_name[_Kind_index[i]:_Kind_index[i+1]]
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/meter.go b/vendor/go.opentelemetry.io/otel/api/metric/meter.go
new file mode 100644
index 0000000..d174913
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/meter.go
@@ -0,0 +1,320 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/label"
+)
+
+// The file is organized as follows:
+//
+//  - MeterProvider interface
+//  - Meter struct
+//  - RecordBatch
+//  - BatchObserver
+//  - Synchronous instrument constructors (2 x int64,float64)
+//  - Asynchronous instrument constructors (1 x int64,float64)
+//  - Batch asynchronous constructors (1 x int64,float64)
+//  - Internals
+
+// MeterProvider supports named Meter instances.
+type MeterProvider interface {
+	// Meter creates an implementation of the Meter interface.
+	// The instrumentationName must be the name of the library providing
+	// instrumentation. This name may be the same as the instrumented code
+	// only if that code provides built-in instrumentation. If the
+	// instrumentationName is empty, then a implementation defined default
+	// name will be used instead.
+	Meter(instrumentationName string, opts ...MeterOption) Meter
+}
+
+// Meter is the OpenTelemetry metric API, based on a `MeterImpl`
+// implementation and the `Meter` library name.
+//
+// An uninitialized Meter is a no-op implementation.
+type Meter struct {
+	impl          MeterImpl
+	name, version string
+}
+
+// RecordBatch atomically records a batch of measurements.
+func (m Meter) RecordBatch(ctx context.Context, ls []label.KeyValue, ms ...Measurement) {
+	if m.impl == nil {
+		return
+	}
+	m.impl.RecordBatch(ctx, ls, ms...)
+}
+
+// NewBatchObserver creates a new BatchObserver that supports
+// making batches of observations for multiple instruments.
+func (m Meter) NewBatchObserver(callback BatchObserverFunc) BatchObserver {
+	return BatchObserver{
+		meter:  m,
+		runner: newBatchAsyncRunner(callback),
+	}
+}
+
+// NewInt64Counter creates a new integer Counter instrument with the
+// given name, customized with options.  May return an error if the
+// name is invalid (e.g., empty) or improperly registered (e.g.,
+// duplicate registration).
+func (m Meter) NewInt64Counter(name string, options ...InstrumentOption) (Int64Counter, error) {
+	return wrapInt64CounterInstrument(
+		m.newSync(name, CounterKind, Int64NumberKind, options))
+}
+
+// NewFloat64Counter creates a new floating point Counter with the
+// given name, customized with options.  May return an error if the
+// name is invalid (e.g., empty) or improperly registered (e.g.,
+// duplicate registration).
+func (m Meter) NewFloat64Counter(name string, options ...InstrumentOption) (Float64Counter, error) {
+	return wrapFloat64CounterInstrument(
+		m.newSync(name, CounterKind, Float64NumberKind, options))
+}
+
+// NewInt64UpDownCounter creates a new integer UpDownCounter instrument with the
+// given name, customized with options.  May return an error if the
+// name is invalid (e.g., empty) or improperly registered (e.g.,
+// duplicate registration).
+func (m Meter) NewInt64UpDownCounter(name string, options ...InstrumentOption) (Int64UpDownCounter, error) {
+	return wrapInt64UpDownCounterInstrument(
+		m.newSync(name, UpDownCounterKind, Int64NumberKind, options))
+}
+
+// NewFloat64UpDownCounter creates a new floating point UpDownCounter with the
+// given name, customized with options.  May return an error if the
+// name is invalid (e.g., empty) or improperly registered (e.g.,
+// duplicate registration).
+func (m Meter) NewFloat64UpDownCounter(name string, options ...InstrumentOption) (Float64UpDownCounter, error) {
+	return wrapFloat64UpDownCounterInstrument(
+		m.newSync(name, UpDownCounterKind, Float64NumberKind, options))
+}
+
+// NewInt64ValueRecorder creates a new integer ValueRecorder instrument with the
+// given name, customized with options.  May return an error if the
+// name is invalid (e.g., empty) or improperly registered (e.g.,
+// duplicate registration).
+func (m Meter) NewInt64ValueRecorder(name string, opts ...InstrumentOption) (Int64ValueRecorder, error) {
+	return wrapInt64ValueRecorderInstrument(
+		m.newSync(name, ValueRecorderKind, Int64NumberKind, opts))
+}
+
+// NewFloat64ValueRecorder creates a new floating point ValueRecorder with the
+// given name, customized with options.  May return an error if the
+// name is invalid (e.g., empty) or improperly registered (e.g.,
+// duplicate registration).
+func (m Meter) NewFloat64ValueRecorder(name string, opts ...InstrumentOption) (Float64ValueRecorder, error) {
+	return wrapFloat64ValueRecorderInstrument(
+		m.newSync(name, ValueRecorderKind, Float64NumberKind, opts))
+}
+
+// NewInt64ValueObserver creates a new integer ValueObserver instrument
+// with the given name, running a given callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (m Meter) NewInt64ValueObserver(name string, callback Int64ObserverFunc, opts ...InstrumentOption) (Int64ValueObserver, error) {
+	if callback == nil {
+		return wrapInt64ValueObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapInt64ValueObserverInstrument(
+		m.newAsync(name, ValueObserverKind, Int64NumberKind, opts,
+			newInt64AsyncRunner(callback)))
+}
+
+// NewFloat64ValueObserver creates a new floating point ValueObserver with
+// the given name, running a given callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (m Meter) NewFloat64ValueObserver(name string, callback Float64ObserverFunc, opts ...InstrumentOption) (Float64ValueObserver, error) {
+	if callback == nil {
+		return wrapFloat64ValueObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapFloat64ValueObserverInstrument(
+		m.newAsync(name, ValueObserverKind, Float64NumberKind, opts,
+			newFloat64AsyncRunner(callback)))
+}
+
+// NewInt64SumObserver creates a new integer SumObserver instrument
+// with the given name, running a given callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (m Meter) NewInt64SumObserver(name string, callback Int64ObserverFunc, opts ...InstrumentOption) (Int64SumObserver, error) {
+	if callback == nil {
+		return wrapInt64SumObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapInt64SumObserverInstrument(
+		m.newAsync(name, SumObserverKind, Int64NumberKind, opts,
+			newInt64AsyncRunner(callback)))
+}
+
+// NewFloat64SumObserver creates a new floating point SumObserver with
+// the given name, running a given callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (m Meter) NewFloat64SumObserver(name string, callback Float64ObserverFunc, opts ...InstrumentOption) (Float64SumObserver, error) {
+	if callback == nil {
+		return wrapFloat64SumObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapFloat64SumObserverInstrument(
+		m.newAsync(name, SumObserverKind, Float64NumberKind, opts,
+			newFloat64AsyncRunner(callback)))
+}
+
+// NewInt64UpDownSumObserver creates a new integer UpDownSumObserver instrument
+// with the given name, running a given callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (m Meter) NewInt64UpDownSumObserver(name string, callback Int64ObserverFunc, opts ...InstrumentOption) (Int64UpDownSumObserver, error) {
+	if callback == nil {
+		return wrapInt64UpDownSumObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapInt64UpDownSumObserverInstrument(
+		m.newAsync(name, UpDownSumObserverKind, Int64NumberKind, opts,
+			newInt64AsyncRunner(callback)))
+}
+
+// NewFloat64UpDownSumObserver creates a new floating point UpDownSumObserver with
+// the given name, running a given callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (m Meter) NewFloat64UpDownSumObserver(name string, callback Float64ObserverFunc, opts ...InstrumentOption) (Float64UpDownSumObserver, error) {
+	if callback == nil {
+		return wrapFloat64UpDownSumObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapFloat64UpDownSumObserverInstrument(
+		m.newAsync(name, UpDownSumObserverKind, Float64NumberKind, opts,
+			newFloat64AsyncRunner(callback)))
+}
+
+// NewInt64ValueObserver creates a new integer ValueObserver instrument
+// with the given name, running in a batch callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (b BatchObserver) NewInt64ValueObserver(name string, opts ...InstrumentOption) (Int64ValueObserver, error) {
+	if b.runner == nil {
+		return wrapInt64ValueObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapInt64ValueObserverInstrument(
+		b.meter.newAsync(name, ValueObserverKind, Int64NumberKind, opts, b.runner))
+}
+
+// NewFloat64ValueObserver creates a new floating point ValueObserver with
+// the given name, running in a batch callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (b BatchObserver) NewFloat64ValueObserver(name string, opts ...InstrumentOption) (Float64ValueObserver, error) {
+	if b.runner == nil {
+		return wrapFloat64ValueObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapFloat64ValueObserverInstrument(
+		b.meter.newAsync(name, ValueObserverKind, Float64NumberKind, opts,
+			b.runner))
+}
+
+// NewInt64SumObserver creates a new integer SumObserver instrument
+// with the given name, running in a batch callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (b BatchObserver) NewInt64SumObserver(name string, opts ...InstrumentOption) (Int64SumObserver, error) {
+	if b.runner == nil {
+		return wrapInt64SumObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapInt64SumObserverInstrument(
+		b.meter.newAsync(name, SumObserverKind, Int64NumberKind, opts, b.runner))
+}
+
+// NewFloat64SumObserver creates a new floating point SumObserver with
+// the given name, running in a batch callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (b BatchObserver) NewFloat64SumObserver(name string, opts ...InstrumentOption) (Float64SumObserver, error) {
+	if b.runner == nil {
+		return wrapFloat64SumObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapFloat64SumObserverInstrument(
+		b.meter.newAsync(name, SumObserverKind, Float64NumberKind, opts,
+			b.runner))
+}
+
+// NewInt64UpDownSumObserver creates a new integer UpDownSumObserver instrument
+// with the given name, running in a batch callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (b BatchObserver) NewInt64UpDownSumObserver(name string, opts ...InstrumentOption) (Int64UpDownSumObserver, error) {
+	if b.runner == nil {
+		return wrapInt64UpDownSumObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapInt64UpDownSumObserverInstrument(
+		b.meter.newAsync(name, UpDownSumObserverKind, Int64NumberKind, opts, b.runner))
+}
+
+// NewFloat64UpDownSumObserver creates a new floating point UpDownSumObserver with
+// the given name, running in a batch callback, and customized with
+// options.  May return an error if the name is invalid (e.g., empty)
+// or improperly registered (e.g., duplicate registration).
+func (b BatchObserver) NewFloat64UpDownSumObserver(name string, opts ...InstrumentOption) (Float64UpDownSumObserver, error) {
+	if b.runner == nil {
+		return wrapFloat64UpDownSumObserverInstrument(NoopAsync{}, nil)
+	}
+	return wrapFloat64UpDownSumObserverInstrument(
+		b.meter.newAsync(name, UpDownSumObserverKind, Float64NumberKind, opts,
+			b.runner))
+}
+
+// MeterImpl returns the underlying MeterImpl of this Meter.
+func (m Meter) MeterImpl() MeterImpl {
+	return m.impl
+}
+
+// newAsync constructs one new asynchronous instrument.
+func (m Meter) newAsync(
+	name string,
+	mkind Kind,
+	nkind NumberKind,
+	opts []InstrumentOption,
+	runner AsyncRunner,
+) (
+	AsyncImpl,
+	error,
+) {
+	if m.impl == nil {
+		return NoopAsync{}, nil
+	}
+	desc := NewDescriptor(name, mkind, nkind, opts...)
+	desc.config.InstrumentationName = m.name
+	desc.config.InstrumentationVersion = m.version
+	return m.impl.NewAsyncInstrument(desc, runner)
+}
+
+// newSync constructs one new synchronous instrument.
+func (m Meter) newSync(
+	name string,
+	metricKind Kind,
+	numberKind NumberKind,
+	opts []InstrumentOption,
+) (
+	SyncImpl,
+	error,
+) {
+	if m.impl == nil {
+		return NoopSync{}, nil
+	}
+	desc := NewDescriptor(name, metricKind, numberKind, opts...)
+	desc.config.InstrumentationName = m.name
+	desc.config.InstrumentationVersion = m.version
+	return m.impl.NewSyncInstrument(desc)
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/must.go b/vendor/go.opentelemetry.io/otel/api/metric/must.go
new file mode 100644
index 0000000..c88e050
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/must.go
@@ -0,0 +1,222 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+// MeterMust is a wrapper for Meter interfaces that panics when any
+// instrument constructor encounters an error.
+type MeterMust struct {
+	meter Meter
+}
+
+// BatchObserverMust is a wrapper for BatchObserver that panics when
+// any instrument constructor encounters an error.
+type BatchObserverMust struct {
+	batch BatchObserver
+}
+
+// Must constructs a MeterMust implementation from a Meter, allowing
+// the application to panic when any instrument constructor yields an
+// error.
+func Must(meter Meter) MeterMust {
+	return MeterMust{meter: meter}
+}
+
+// NewInt64Counter calls `Meter.NewInt64Counter` and returns the
+// instrument, panicking if it encounters an error.
+func (mm MeterMust) NewInt64Counter(name string, cos ...InstrumentOption) Int64Counter {
+	if inst, err := mm.meter.NewInt64Counter(name, cos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewFloat64Counter calls `Meter.NewFloat64Counter` and returns the
+// instrument, panicking if it encounters an error.
+func (mm MeterMust) NewFloat64Counter(name string, cos ...InstrumentOption) Float64Counter {
+	if inst, err := mm.meter.NewFloat64Counter(name, cos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewInt64UpDownCounter calls `Meter.NewInt64UpDownCounter` and returns the
+// instrument, panicking if it encounters an error.
+func (mm MeterMust) NewInt64UpDownCounter(name string, cos ...InstrumentOption) Int64UpDownCounter {
+	if inst, err := mm.meter.NewInt64UpDownCounter(name, cos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewFloat64UpDownCounter calls `Meter.NewFloat64UpDownCounter` and returns the
+// instrument, panicking if it encounters an error.
+func (mm MeterMust) NewFloat64UpDownCounter(name string, cos ...InstrumentOption) Float64UpDownCounter {
+	if inst, err := mm.meter.NewFloat64UpDownCounter(name, cos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewInt64ValueRecorder calls `Meter.NewInt64ValueRecorder` and returns the
+// instrument, panicking if it encounters an error.
+func (mm MeterMust) NewInt64ValueRecorder(name string, mos ...InstrumentOption) Int64ValueRecorder {
+	if inst, err := mm.meter.NewInt64ValueRecorder(name, mos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewFloat64ValueRecorder calls `Meter.NewFloat64ValueRecorder` and returns the
+// instrument, panicking if it encounters an error.
+func (mm MeterMust) NewFloat64ValueRecorder(name string, mos ...InstrumentOption) Float64ValueRecorder {
+	if inst, err := mm.meter.NewFloat64ValueRecorder(name, mos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewInt64ValueObserver calls `Meter.NewInt64ValueObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (mm MeterMust) NewInt64ValueObserver(name string, callback Int64ObserverFunc, oos ...InstrumentOption) Int64ValueObserver {
+	if inst, err := mm.meter.NewInt64ValueObserver(name, callback, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewFloat64ValueObserver calls `Meter.NewFloat64ValueObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (mm MeterMust) NewFloat64ValueObserver(name string, callback Float64ObserverFunc, oos ...InstrumentOption) Float64ValueObserver {
+	if inst, err := mm.meter.NewFloat64ValueObserver(name, callback, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewInt64SumObserver calls `Meter.NewInt64SumObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (mm MeterMust) NewInt64SumObserver(name string, callback Int64ObserverFunc, oos ...InstrumentOption) Int64SumObserver {
+	if inst, err := mm.meter.NewInt64SumObserver(name, callback, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewFloat64SumObserver calls `Meter.NewFloat64SumObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (mm MeterMust) NewFloat64SumObserver(name string, callback Float64ObserverFunc, oos ...InstrumentOption) Float64SumObserver {
+	if inst, err := mm.meter.NewFloat64SumObserver(name, callback, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewInt64UpDownSumObserver calls `Meter.NewInt64UpDownSumObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (mm MeterMust) NewInt64UpDownSumObserver(name string, callback Int64ObserverFunc, oos ...InstrumentOption) Int64UpDownSumObserver {
+	if inst, err := mm.meter.NewInt64UpDownSumObserver(name, callback, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewFloat64UpDownSumObserver calls `Meter.NewFloat64UpDownSumObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (mm MeterMust) NewFloat64UpDownSumObserver(name string, callback Float64ObserverFunc, oos ...InstrumentOption) Float64UpDownSumObserver {
+	if inst, err := mm.meter.NewFloat64UpDownSumObserver(name, callback, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewBatchObserver returns a wrapper around BatchObserver that panics
+// when any instrument constructor returns an error.
+func (mm MeterMust) NewBatchObserver(callback BatchObserverFunc) BatchObserverMust {
+	return BatchObserverMust{
+		batch: mm.meter.NewBatchObserver(callback),
+	}
+}
+
+// NewInt64ValueObserver calls `BatchObserver.NewInt64ValueObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (bm BatchObserverMust) NewInt64ValueObserver(name string, oos ...InstrumentOption) Int64ValueObserver {
+	if inst, err := bm.batch.NewInt64ValueObserver(name, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewFloat64ValueObserver calls `BatchObserver.NewFloat64ValueObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (bm BatchObserverMust) NewFloat64ValueObserver(name string, oos ...InstrumentOption) Float64ValueObserver {
+	if inst, err := bm.batch.NewFloat64ValueObserver(name, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewInt64SumObserver calls `BatchObserver.NewInt64SumObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (bm BatchObserverMust) NewInt64SumObserver(name string, oos ...InstrumentOption) Int64SumObserver {
+	if inst, err := bm.batch.NewInt64SumObserver(name, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewFloat64SumObserver calls `BatchObserver.NewFloat64SumObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (bm BatchObserverMust) NewFloat64SumObserver(name string, oos ...InstrumentOption) Float64SumObserver {
+	if inst, err := bm.batch.NewFloat64SumObserver(name, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewInt64UpDownSumObserver calls `BatchObserver.NewInt64UpDownSumObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (bm BatchObserverMust) NewInt64UpDownSumObserver(name string, oos ...InstrumentOption) Int64UpDownSumObserver {
+	if inst, err := bm.batch.NewInt64UpDownSumObserver(name, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
+
+// NewFloat64UpDownSumObserver calls `BatchObserver.NewFloat64UpDownSumObserver` and
+// returns the instrument, panicking if it encounters an error.
+func (bm BatchObserverMust) NewFloat64UpDownSumObserver(name string, oos ...InstrumentOption) Float64UpDownSumObserver {
+	if inst, err := bm.batch.NewFloat64UpDownSumObserver(name, oos...); err != nil {
+		panic(err)
+	} else {
+		return inst
+	}
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/noop.go b/vendor/go.opentelemetry.io/otel/api/metric/noop.go
new file mode 100644
index 0000000..97867d9
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/noop.go
@@ -0,0 +1,58 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/label"
+)
+
+type NoopMeterProvider struct{}
+
+type noopInstrument struct{}
+type noopBoundInstrument struct{}
+type NoopSync struct{ noopInstrument }
+type NoopAsync struct{ noopInstrument }
+
+var _ MeterProvider = NoopMeterProvider{}
+var _ SyncImpl = NoopSync{}
+var _ BoundSyncImpl = noopBoundInstrument{}
+var _ AsyncImpl = NoopAsync{}
+
+func (NoopMeterProvider) Meter(_ string, _ ...MeterOption) Meter {
+	return Meter{}
+}
+
+func (noopInstrument) Implementation() interface{} {
+	return nil
+}
+
+func (noopInstrument) Descriptor() Descriptor {
+	return Descriptor{}
+}
+
+func (noopBoundInstrument) RecordOne(context.Context, Number) {
+}
+
+func (noopBoundInstrument) Unbind() {
+}
+
+func (NoopSync) Bind([]label.KeyValue) BoundSyncImpl {
+	return noopBoundInstrument{}
+}
+
+func (NoopSync) RecordOne(context.Context, Number, []label.KeyValue) {
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/number.go b/vendor/go.opentelemetry.io/otel/api/metric/number.go
new file mode 100644
index 0000000..c3ca0ed
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/number.go
@@ -0,0 +1,540 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+//go:generate stringer -type=NumberKind
+
+import (
+	"fmt"
+	"math"
+	"sync/atomic"
+
+	"go.opentelemetry.io/otel/internal"
+)
+
+// NumberKind describes the data type of the Number.
+type NumberKind int8
+
+const (
+	// Int64NumberKind means that the Number stores int64.
+	Int64NumberKind NumberKind = iota
+	// Float64NumberKind means that the Number stores float64.
+	Float64NumberKind
+)
+
+// Zero returns a zero value for a given NumberKind
+func (k NumberKind) Zero() Number {
+	switch k {
+	case Int64NumberKind:
+		return NewInt64Number(0)
+	case Float64NumberKind:
+		return NewFloat64Number(0.)
+	default:
+		return Number(0)
+	}
+}
+
+// Minimum returns the minimum representable value
+// for a given NumberKind
+func (k NumberKind) Minimum() Number {
+	switch k {
+	case Int64NumberKind:
+		return NewInt64Number(math.MinInt64)
+	case Float64NumberKind:
+		return NewFloat64Number(-1. * math.MaxFloat64)
+	default:
+		return Number(0)
+	}
+}
+
+// Maximum returns the maximum representable value
+// for a given NumberKind
+func (k NumberKind) Maximum() Number {
+	switch k {
+	case Int64NumberKind:
+		return NewInt64Number(math.MaxInt64)
+	case Float64NumberKind:
+		return NewFloat64Number(math.MaxFloat64)
+	default:
+		return Number(0)
+	}
+}
+
+// Number represents either an integral or a floating point value. It
+// needs to be accompanied with a source of NumberKind that describes
+// the actual type of the value stored within Number.
+type Number uint64
+
+// - constructors
+
+// NewNumberFromRaw creates a new Number from a raw value.
+func NewNumberFromRaw(r uint64) Number {
+	return Number(r)
+}
+
+// NewInt64Number creates an integral Number.
+func NewInt64Number(i int64) Number {
+	return NewNumberFromRaw(internal.Int64ToRaw(i))
+}
+
+// NewFloat64Number creates a floating point Number.
+func NewFloat64Number(f float64) Number {
+	return NewNumberFromRaw(internal.Float64ToRaw(f))
+}
+
+// NewNumberSignChange returns a number with the same magnitude and
+// the opposite sign.  `kind` must describe the kind of number in `nn`.
+//
+// Does not change Uint64NumberKind values.
+func NewNumberSignChange(kind NumberKind, nn Number) Number {
+	switch kind {
+	case Int64NumberKind:
+		return NewInt64Number(-nn.AsInt64())
+	case Float64NumberKind:
+		return NewFloat64Number(-nn.AsFloat64())
+	}
+	return nn
+}
+
+// - as x
+
+// AsNumber gets the Number.
+func (n *Number) AsNumber() Number {
+	return *n
+}
+
+// AsRaw gets the uninterpreted raw value. Might be useful for some
+// atomic operations.
+func (n *Number) AsRaw() uint64 {
+	return uint64(*n)
+}
+
+// AsInt64 assumes that the value contains an int64 and returns it as
+// such.
+func (n *Number) AsInt64() int64 {
+	return internal.RawToInt64(n.AsRaw())
+}
+
+// AsFloat64 assumes that the measurement value contains a float64 and
+// returns it as such.
+func (n *Number) AsFloat64() float64 {
+	return internal.RawToFloat64(n.AsRaw())
+}
+
+// - as x atomic
+
+// AsNumberAtomic gets the Number atomically.
+func (n *Number) AsNumberAtomic() Number {
+	return NewNumberFromRaw(n.AsRawAtomic())
+}
+
+// AsRawAtomic gets the uninterpreted raw value atomically. Might be
+// useful for some atomic operations.
+func (n *Number) AsRawAtomic() uint64 {
+	return atomic.LoadUint64(n.AsRawPtr())
+}
+
+// AsInt64Atomic assumes that the number contains an int64 and returns
+// it as such atomically.
+func (n *Number) AsInt64Atomic() int64 {
+	return atomic.LoadInt64(n.AsInt64Ptr())
+}
+
+// AsFloat64Atomic assumes that the measurement value contains a
+// float64 and returns it as such atomically.
+func (n *Number) AsFloat64Atomic() float64 {
+	return internal.RawToFloat64(n.AsRawAtomic())
+}
+
+// - as x ptr
+
+// AsRawPtr gets the pointer to the raw, uninterpreted raw
+// value. Might be useful for some atomic operations.
+func (n *Number) AsRawPtr() *uint64 {
+	return (*uint64)(n)
+}
+
+// AsInt64Ptr assumes that the number contains an int64 and returns a
+// pointer to it.
+func (n *Number) AsInt64Ptr() *int64 {
+	return internal.RawPtrToInt64Ptr(n.AsRawPtr())
+}
+
+// AsFloat64Ptr assumes that the number contains a float64 and returns a
+// pointer to it.
+func (n *Number) AsFloat64Ptr() *float64 {
+	return internal.RawPtrToFloat64Ptr(n.AsRawPtr())
+}
+
+// - coerce
+
+// CoerceToInt64 casts the number to int64. May result in
+// data/precision loss.
+func (n *Number) CoerceToInt64(kind NumberKind) int64 {
+	switch kind {
+	case Int64NumberKind:
+		return n.AsInt64()
+	case Float64NumberKind:
+		return int64(n.AsFloat64())
+	default:
+		// you get what you deserve
+		return 0
+	}
+}
+
+// CoerceToFloat64 casts the number to float64. May result in
+// data/precision loss.
+func (n *Number) CoerceToFloat64(kind NumberKind) float64 {
+	switch kind {
+	case Int64NumberKind:
+		return float64(n.AsInt64())
+	case Float64NumberKind:
+		return n.AsFloat64()
+	default:
+		// you get what you deserve
+		return 0
+	}
+}
+
+// - set
+
+// SetNumber sets the number to the passed number. Both should be of
+// the same kind.
+func (n *Number) SetNumber(nn Number) {
+	*n.AsRawPtr() = nn.AsRaw()
+}
+
+// SetRaw sets the number to the passed raw value. Both number and the
+// raw number should represent the same kind.
+func (n *Number) SetRaw(r uint64) {
+	*n.AsRawPtr() = r
+}
+
+// SetInt64 assumes that the number contains an int64 and sets it to
+// the passed value.
+func (n *Number) SetInt64(i int64) {
+	*n.AsInt64Ptr() = i
+}
+
+// SetFloat64 assumes that the number contains a float64 and sets it
+// to the passed value.
+func (n *Number) SetFloat64(f float64) {
+	*n.AsFloat64Ptr() = f
+}
+
+// - set atomic
+
+// SetNumberAtomic sets the number to the passed number
+// atomically. Both should be of the same kind.
+func (n *Number) SetNumberAtomic(nn Number) {
+	atomic.StoreUint64(n.AsRawPtr(), nn.AsRaw())
+}
+
+// SetRawAtomic sets the number to the passed raw value
+// atomically. Both number and the raw number should represent the
+// same kind.
+func (n *Number) SetRawAtomic(r uint64) {
+	atomic.StoreUint64(n.AsRawPtr(), r)
+}
+
+// SetInt64Atomic assumes that the number contains an int64 and sets
+// it to the passed value atomically.
+func (n *Number) SetInt64Atomic(i int64) {
+	atomic.StoreInt64(n.AsInt64Ptr(), i)
+}
+
+// SetFloat64Atomic assumes that the number contains a float64 and
+// sets it to the passed value atomically.
+func (n *Number) SetFloat64Atomic(f float64) {
+	atomic.StoreUint64(n.AsRawPtr(), internal.Float64ToRaw(f))
+}
+
+// - swap
+
+// SwapNumber sets the number to the passed number and returns the old
+// number. Both this number and the passed number should be of the
+// same kind.
+func (n *Number) SwapNumber(nn Number) Number {
+	old := *n
+	n.SetNumber(nn)
+	return old
+}
+
+// SwapRaw sets the number to the passed raw value and returns the old
+// raw value. Both number and the raw number should represent the same
+// kind.
+func (n *Number) SwapRaw(r uint64) uint64 {
+	old := n.AsRaw()
+	n.SetRaw(r)
+	return old
+}
+
+// SwapInt64 assumes that the number contains an int64, sets it to the
+// passed value and returns the old int64 value.
+func (n *Number) SwapInt64(i int64) int64 {
+	old := n.AsInt64()
+	n.SetInt64(i)
+	return old
+}
+
+// SwapFloat64 assumes that the number contains an float64, sets it to
+// the passed value and returns the old float64 value.
+func (n *Number) SwapFloat64(f float64) float64 {
+	old := n.AsFloat64()
+	n.SetFloat64(f)
+	return old
+}
+
+// - swap atomic
+
+// SwapNumberAtomic sets the number to the passed number and returns
+// the old number atomically. Both this number and the passed number
+// should be of the same kind.
+func (n *Number) SwapNumberAtomic(nn Number) Number {
+	return NewNumberFromRaw(atomic.SwapUint64(n.AsRawPtr(), nn.AsRaw()))
+}
+
+// SwapRawAtomic sets the number to the passed raw value and returns
+// the old raw value atomically. Both number and the raw number should
+// represent the same kind.
+func (n *Number) SwapRawAtomic(r uint64) uint64 {
+	return atomic.SwapUint64(n.AsRawPtr(), r)
+}
+
+// SwapInt64Atomic assumes that the number contains an int64, sets it
+// to the passed value and returns the old int64 value atomically.
+func (n *Number) SwapInt64Atomic(i int64) int64 {
+	return atomic.SwapInt64(n.AsInt64Ptr(), i)
+}
+
+// SwapFloat64Atomic assumes that the number contains an float64, sets
+// it to the passed value and returns the old float64 value
+// atomically.
+func (n *Number) SwapFloat64Atomic(f float64) float64 {
+	return internal.RawToFloat64(atomic.SwapUint64(n.AsRawPtr(), internal.Float64ToRaw(f)))
+}
+
+// - add
+
+// AddNumber assumes that this and the passed number are of the passed
+// kind and adds the passed number to this number.
+func (n *Number) AddNumber(kind NumberKind, nn Number) {
+	switch kind {
+	case Int64NumberKind:
+		n.AddInt64(nn.AsInt64())
+	case Float64NumberKind:
+		n.AddFloat64(nn.AsFloat64())
+	}
+}
+
+// AddRaw assumes that this number and the passed raw value are of the
+// passed kind and adds the passed raw value to this number.
+func (n *Number) AddRaw(kind NumberKind, r uint64) {
+	n.AddNumber(kind, NewNumberFromRaw(r))
+}
+
+// AddInt64 assumes that the number contains an int64 and adds the
+// passed int64 to it.
+func (n *Number) AddInt64(i int64) {
+	*n.AsInt64Ptr() += i
+}
+
+// AddFloat64 assumes that the number contains a float64 and adds the
+// passed float64 to it.
+func (n *Number) AddFloat64(f float64) {
+	*n.AsFloat64Ptr() += f
+}
+
+// - add atomic
+
+// AddNumberAtomic assumes that this and the passed number are of the
+// passed kind and adds the passed number to this number atomically.
+func (n *Number) AddNumberAtomic(kind NumberKind, nn Number) {
+	switch kind {
+	case Int64NumberKind:
+		n.AddInt64Atomic(nn.AsInt64())
+	case Float64NumberKind:
+		n.AddFloat64Atomic(nn.AsFloat64())
+	}
+}
+
+// AddRawAtomic assumes that this number and the passed raw value are
+// of the passed kind and adds the passed raw value to this number
+// atomically.
+func (n *Number) AddRawAtomic(kind NumberKind, r uint64) {
+	n.AddNumberAtomic(kind, NewNumberFromRaw(r))
+}
+
+// AddInt64Atomic assumes that the number contains an int64 and adds
+// the passed int64 to it atomically.
+func (n *Number) AddInt64Atomic(i int64) {
+	atomic.AddInt64(n.AsInt64Ptr(), i)
+}
+
+// AddFloat64Atomic assumes that the number contains a float64 and
+// adds the passed float64 to it atomically.
+func (n *Number) AddFloat64Atomic(f float64) {
+	for {
+		o := n.AsFloat64Atomic()
+		if n.CompareAndSwapFloat64(o, o+f) {
+			break
+		}
+	}
+}
+
+// - compare and swap (atomic only)
+
+// CompareAndSwapNumber does the atomic CAS operation on this
+// number. This number and passed old and new numbers should be of the
+// same kind.
+func (n *Number) CompareAndSwapNumber(on, nn Number) bool {
+	return atomic.CompareAndSwapUint64(n.AsRawPtr(), on.AsRaw(), nn.AsRaw())
+}
+
+// CompareAndSwapRaw does the atomic CAS operation on this
+// number. This number and passed old and new raw values should be of
+// the same kind.
+func (n *Number) CompareAndSwapRaw(or, nr uint64) bool {
+	return atomic.CompareAndSwapUint64(n.AsRawPtr(), or, nr)
+}
+
+// CompareAndSwapInt64 assumes that this number contains an int64 and
+// does the atomic CAS operation on it.
+func (n *Number) CompareAndSwapInt64(oi, ni int64) bool {
+	return atomic.CompareAndSwapInt64(n.AsInt64Ptr(), oi, ni)
+}
+
+// CompareAndSwapFloat64 assumes that this number contains a float64 and
+// does the atomic CAS operation on it.
+func (n *Number) CompareAndSwapFloat64(of, nf float64) bool {
+	return atomic.CompareAndSwapUint64(n.AsRawPtr(), internal.Float64ToRaw(of), internal.Float64ToRaw(nf))
+}
+
+// - compare
+
+// CompareNumber compares two Numbers given their kind.  Both numbers
+// should have the same kind.  This returns:
+//    0 if the numbers are equal
+//    -1 if the subject `n` is less than the argument `nn`
+//    +1 if the subject `n` is greater than the argument `nn`
+func (n *Number) CompareNumber(kind NumberKind, nn Number) int {
+	switch kind {
+	case Int64NumberKind:
+		return n.CompareInt64(nn.AsInt64())
+	case Float64NumberKind:
+		return n.CompareFloat64(nn.AsFloat64())
+	default:
+		// you get what you deserve
+		return 0
+	}
+}
+
+// CompareRaw compares two numbers, where one is input as a raw
+// uint64, interpreting both values as a `kind` of number.
+func (n *Number) CompareRaw(kind NumberKind, r uint64) int {
+	return n.CompareNumber(kind, NewNumberFromRaw(r))
+}
+
+// CompareInt64 assumes that the Number contains an int64 and performs
+// a comparison between the value and the other value. It returns the
+// typical result of the compare function: -1 if the value is less
+// than the other, 0 if both are equal, 1 if the value is greater than
+// the other.
+func (n *Number) CompareInt64(i int64) int {
+	this := n.AsInt64()
+	if this < i {
+		return -1
+	} else if this > i {
+		return 1
+	}
+	return 0
+}
+
+// CompareFloat64 assumes that the Number contains a float64 and
+// performs a comparison between the value and the other value. It
+// returns the typical result of the compare function: -1 if the value
+// is less than the other, 0 if both are equal, 1 if the value is
+// greater than the other.
+//
+// Do not compare NaN values.
+func (n *Number) CompareFloat64(f float64) int {
+	this := n.AsFloat64()
+	if this < f {
+		return -1
+	} else if this > f {
+		return 1
+	}
+	return 0
+}
+
+// - relations to zero
+
+// IsPositive returns true if the actual value is greater than zero.
+func (n *Number) IsPositive(kind NumberKind) bool {
+	return n.compareWithZero(kind) > 0
+}
+
+// IsNegative returns true if the actual value is less than zero.
+func (n *Number) IsNegative(kind NumberKind) bool {
+	return n.compareWithZero(kind) < 0
+}
+
+// IsZero returns true if the actual value is equal to zero.
+func (n *Number) IsZero(kind NumberKind) bool {
+	return n.compareWithZero(kind) == 0
+}
+
+// - misc
+
+// Emit returns a string representation of the raw value of the
+// Number. A %d is used for integral values, %f for floating point
+// values.
+func (n *Number) Emit(kind NumberKind) string {
+	switch kind {
+	case Int64NumberKind:
+		return fmt.Sprintf("%d", n.AsInt64())
+	case Float64NumberKind:
+		return fmt.Sprintf("%f", n.AsFloat64())
+	default:
+		return ""
+	}
+}
+
+// AsInterface returns the number as an interface{}, typically used
+// for NumberKind-correct JSON conversion.
+func (n *Number) AsInterface(kind NumberKind) interface{} {
+	switch kind {
+	case Int64NumberKind:
+		return n.AsInt64()
+	case Float64NumberKind:
+		return n.AsFloat64()
+	default:
+		return math.NaN()
+	}
+}
+
+// - private stuff
+
+func (n *Number) compareWithZero(kind NumberKind) int {
+	switch kind {
+	case Int64NumberKind:
+		return n.CompareInt64(0)
+	case Float64NumberKind:
+		return n.CompareFloat64(0.)
+	default:
+		// you get what you deserve
+		return 0
+	}
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/numberkind_string.go b/vendor/go.opentelemetry.io/otel/api/metric/numberkind_string.go
new file mode 100644
index 0000000..e99a874
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/numberkind_string.go
@@ -0,0 +1,24 @@
+// Code generated by "stringer -type=NumberKind"; DO NOT EDIT.
+
+package metric
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[Int64NumberKind-0]
+	_ = x[Float64NumberKind-1]
+}
+
+const _NumberKind_name = "Int64NumberKindFloat64NumberKind"
+
+var _NumberKind_index = [...]uint8{0, 15, 32}
+
+func (i NumberKind) String() string {
+	if i < 0 || i >= NumberKind(len(_NumberKind_index)-1) {
+		return "NumberKind(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _NumberKind_name[_NumberKind_index[i]:_NumberKind_index[i+1]]
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/observer.go b/vendor/go.opentelemetry.io/otel/api/metric/observer.go
new file mode 100644
index 0000000..c347da7
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/observer.go
@@ -0,0 +1,124 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+// BatchObserver represents an Observer callback that can report
+// observations for multiple instruments.
+type BatchObserver struct {
+	meter  Meter
+	runner AsyncBatchRunner
+}
+
+// Int64ValueObserver is a metric that captures a set of int64 values at a
+// point in time.
+type Int64ValueObserver struct {
+	asyncInstrument
+}
+
+// Float64ValueObserver is a metric that captures a set of float64 values
+// at a point in time.
+type Float64ValueObserver struct {
+	asyncInstrument
+}
+
+// Int64SumObserver is a metric that captures a precomputed sum of
+// int64 values at a point in time.
+type Int64SumObserver struct {
+	asyncInstrument
+}
+
+// Float64SumObserver is a metric that captures a precomputed sum of
+// float64 values at a point in time.
+type Float64SumObserver struct {
+	asyncInstrument
+}
+
+// Int64UpDownSumObserver is a metric that captures a precomputed sum of
+// int64 values at a point in time.
+type Int64UpDownSumObserver struct {
+	asyncInstrument
+}
+
+// Float64UpDownSumObserver is a metric that captures a precomputed sum of
+// float64 values at a point in time.
+type Float64UpDownSumObserver struct {
+	asyncInstrument
+}
+
+// Observation returns an Observation, a BatchObserverFunc
+// argument, for an asynchronous integer instrument.
+// This returns an implementation-level object for use by the SDK,
+// users should not refer to this.
+func (i Int64ValueObserver) Observation(v int64) Observation {
+	return Observation{
+		number:     NewInt64Number(v),
+		instrument: i.instrument,
+	}
+}
+
+// Observation returns an Observation, a BatchObserverFunc
+// argument, for an asynchronous integer instrument.
+// This returns an implementation-level object for use by the SDK,
+// users should not refer to this.
+func (f Float64ValueObserver) Observation(v float64) Observation {
+	return Observation{
+		number:     NewFloat64Number(v),
+		instrument: f.instrument,
+	}
+}
+
+// Observation returns an Observation, a BatchObserverFunc
+// argument, for an asynchronous integer instrument.
+// This returns an implementation-level object for use by the SDK,
+// users should not refer to this.
+func (i Int64SumObserver) Observation(v int64) Observation {
+	return Observation{
+		number:     NewInt64Number(v),
+		instrument: i.instrument,
+	}
+}
+
+// Observation returns an Observation, a BatchObserverFunc
+// argument, for an asynchronous integer instrument.
+// This returns an implementation-level object for use by the SDK,
+// users should not refer to this.
+func (f Float64SumObserver) Observation(v float64) Observation {
+	return Observation{
+		number:     NewFloat64Number(v),
+		instrument: f.instrument,
+	}
+}
+
+// Observation returns an Observation, a BatchObserverFunc
+// argument, for an asynchronous integer instrument.
+// This returns an implementation-level object for use by the SDK,
+// users should not refer to this.
+func (i Int64UpDownSumObserver) Observation(v int64) Observation {
+	return Observation{
+		number:     NewInt64Number(v),
+		instrument: i.instrument,
+	}
+}
+
+// Observation returns an Observation, a BatchObserverFunc
+// argument, for an asynchronous integer instrument.
+// This returns an implementation-level object for use by the SDK,
+// users should not refer to this.
+func (f Float64UpDownSumObserver) Observation(v float64) Observation {
+	return Observation{
+		number:     NewFloat64Number(v),
+		instrument: f.instrument,
+	}
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/registry/registry.go b/vendor/go.opentelemetry.io/otel/api/metric/registry/registry.go
new file mode 100644
index 0000000..ed9eccc
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/registry/registry.go
@@ -0,0 +1,170 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package registry // import "go.opentelemetry.io/otel/api/metric/registry"
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"go.opentelemetry.io/otel/api/metric"
+	"go.opentelemetry.io/otel/label"
+)
+
+// MeterProvider is a standard MeterProvider for wrapping `MeterImpl`
+type MeterProvider struct {
+	impl metric.MeterImpl
+}
+
+var _ metric.MeterProvider = (*MeterProvider)(nil)
+
+// uniqueInstrumentMeterImpl implements the metric.MeterImpl interface, adding
+// uniqueness checking for instrument descriptors.  Use NewUniqueInstrumentMeter
+// to wrap an implementation with uniqueness checking.
+type uniqueInstrumentMeterImpl struct {
+	lock  sync.Mutex
+	impl  metric.MeterImpl
+	state map[key]metric.InstrumentImpl
+}
+
+var _ metric.MeterImpl = (*uniqueInstrumentMeterImpl)(nil)
+
+type key struct {
+	instrumentName         string
+	instrumentationName    string
+	InstrumentationVersion string
+}
+
+// NewMeterProvider returns a new provider that implements instrument
+// name-uniqueness checking.
+func NewMeterProvider(impl metric.MeterImpl) *MeterProvider {
+	return &MeterProvider{
+		impl: NewUniqueInstrumentMeterImpl(impl),
+	}
+}
+
+// Meter implements MeterProvider.
+func (p *MeterProvider) Meter(instrumentationName string, opts ...metric.MeterOption) metric.Meter {
+	return metric.WrapMeterImpl(p.impl, instrumentationName, opts...)
+}
+
+// ErrMetricKindMismatch is the standard error for mismatched metric
+// instrument definitions.
+var ErrMetricKindMismatch = fmt.Errorf(
+	"A metric was already registered by this name with another kind or number type")
+
+// NewUniqueInstrumentMeterImpl returns a wrapped metric.MeterImpl with
+// the addition of uniqueness checking.
+func NewUniqueInstrumentMeterImpl(impl metric.MeterImpl) metric.MeterImpl {
+	return &uniqueInstrumentMeterImpl{
+		impl:  impl,
+		state: map[key]metric.InstrumentImpl{},
+	}
+}
+
+// RecordBatch implements metric.MeterImpl.
+func (u *uniqueInstrumentMeterImpl) RecordBatch(ctx context.Context, labels []label.KeyValue, ms ...metric.Measurement) {
+	u.impl.RecordBatch(ctx, labels, ms...)
+}
+
+func keyOf(descriptor metric.Descriptor) key {
+	return key{
+		descriptor.Name(),
+		descriptor.InstrumentationName(),
+		descriptor.InstrumentationVersion(),
+	}
+}
+
+// NewMetricKindMismatchError formats an error that describes a
+// mismatched metric instrument definition.
+func NewMetricKindMismatchError(desc metric.Descriptor) error {
+	return fmt.Errorf("Metric was %s (%s %s)registered as a %s %s: %w",
+		desc.Name(),
+		desc.InstrumentationName(),
+		desc.InstrumentationVersion(),
+		desc.NumberKind(),
+		desc.MetricKind(),
+		ErrMetricKindMismatch)
+}
+
+// Compatible determines whether two metric.Descriptors are considered
+// the same for the purpose of uniqueness checking.
+func Compatible(candidate, existing metric.Descriptor) bool {
+	return candidate.MetricKind() == existing.MetricKind() &&
+		candidate.NumberKind() == existing.NumberKind()
+}
+
+// checkUniqueness returns an ErrMetricKindMismatch error if there is
+// a conflict between a descriptor that was already registered and the
+// `descriptor` argument.  If there is an existing compatible
+// registration, this returns the already-registered instrument.  If
+// there is no conflict and no prior registration, returns (nil, nil).
+func (u *uniqueInstrumentMeterImpl) checkUniqueness(descriptor metric.Descriptor) (metric.InstrumentImpl, error) {
+	impl, ok := u.state[keyOf(descriptor)]
+	if !ok {
+		return nil, nil
+	}
+
+	if !Compatible(descriptor, impl.Descriptor()) {
+		return nil, NewMetricKindMismatchError(impl.Descriptor())
+	}
+
+	return impl, nil
+}
+
+// NewSyncInstrument implements metric.MeterImpl.
+func (u *uniqueInstrumentMeterImpl) NewSyncInstrument(descriptor metric.Descriptor) (metric.SyncImpl, error) {
+	u.lock.Lock()
+	defer u.lock.Unlock()
+
+	impl, err := u.checkUniqueness(descriptor)
+
+	if err != nil {
+		return nil, err
+	} else if impl != nil {
+		return impl.(metric.SyncImpl), nil
+	}
+
+	syncInst, err := u.impl.NewSyncInstrument(descriptor)
+	if err != nil {
+		return nil, err
+	}
+	u.state[keyOf(descriptor)] = syncInst
+	return syncInst, nil
+}
+
+// NewAsyncInstrument implements metric.MeterImpl.
+func (u *uniqueInstrumentMeterImpl) NewAsyncInstrument(
+	descriptor metric.Descriptor,
+	runner metric.AsyncRunner,
+) (metric.AsyncImpl, error) {
+	u.lock.Lock()
+	defer u.lock.Unlock()
+
+	impl, err := u.checkUniqueness(descriptor)
+
+	if err != nil {
+		return nil, err
+	} else if impl != nil {
+		return impl.(metric.AsyncImpl), nil
+	}
+
+	asyncInst, err := u.impl.NewAsyncInstrument(descriptor, runner)
+	if err != nil {
+		return nil, err
+	}
+	u.state[keyOf(descriptor)] = asyncInst
+	return asyncInst, nil
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/sdkapi.go b/vendor/go.opentelemetry.io/otel/api/metric/sdkapi.go
new file mode 100644
index 0000000..122c9ba
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/sdkapi.go
@@ -0,0 +1,94 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/label"
+)
+
+// MeterImpl is the interface an SDK must implement to supply a Meter
+// implementation.
+type MeterImpl interface {
+	// RecordBatch atomically records a batch of measurements.
+	RecordBatch(ctx context.Context, labels []label.KeyValue, measurement ...Measurement)
+
+	// NewSyncInstrument returns a newly constructed
+	// synchronous instrument implementation or an error, should
+	// one occur.
+	NewSyncInstrument(descriptor Descriptor) (SyncImpl, error)
+
+	// NewAsyncInstrument returns a newly constructed
+	// asynchronous instrument implementation or an error, should
+	// one occur.
+	NewAsyncInstrument(
+		descriptor Descriptor,
+		runner AsyncRunner,
+	) (AsyncImpl, error)
+}
+
+// InstrumentImpl is a common interface for synchronous and
+// asynchronous instruments.
+type InstrumentImpl interface {
+	// Implementation returns the underlying implementation of the
+	// instrument, which allows the implementation to gain access
+	// to its own representation especially from a `Measurement`.
+	Implementation() interface{}
+
+	// Descriptor returns a copy of the instrument's Descriptor.
+	Descriptor() Descriptor
+}
+
+// SyncImpl is the implementation-level interface to a generic
+// synchronous instrument (e.g., ValueRecorder and Counter instruments).
+type SyncImpl interface {
+	InstrumentImpl
+
+	// Bind creates an implementation-level bound instrument,
+	// binding a label set with this instrument implementation.
+	Bind(labels []label.KeyValue) BoundSyncImpl
+
+	// RecordOne captures a single synchronous metric event.
+	RecordOne(ctx context.Context, number Number, labels []label.KeyValue)
+}
+
+// BoundSyncImpl is the implementation-level interface to a
+// generic bound synchronous instrument
+type BoundSyncImpl interface {
+
+	// RecordOne captures a single synchronous metric event.
+	RecordOne(ctx context.Context, number Number)
+
+	// Unbind frees the resources associated with this bound instrument. It
+	// does not affect the metric this bound instrument was created through.
+	Unbind()
+}
+
+// AsyncImpl is an implementation-level interface to an
+// asynchronous instrument (e.g., Observer instruments).
+type AsyncImpl interface {
+	InstrumentImpl
+}
+
+// WrapMeterImpl constructs a `Meter` implementation from a
+// `MeterImpl` implementation.
+func WrapMeterImpl(impl MeterImpl, instrumentationName string, opts ...MeterOption) Meter {
+	return Meter{
+		impl:    impl,
+		name:    instrumentationName,
+		version: NewMeterConfig(opts...).InstrumentationVersion,
+	}
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/sync.go b/vendor/go.opentelemetry.io/otel/api/metric/sync.go
new file mode 100644
index 0000000..a08a65b
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/sync.go
@@ -0,0 +1,192 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import (
+	"context"
+	"errors"
+
+	"go.opentelemetry.io/otel/label"
+)
+
+// ErrSDKReturnedNilImpl is returned when a new `MeterImpl` returns nil.
+var ErrSDKReturnedNilImpl = errors.New("SDK returned a nil implementation")
+
+// Measurement is used for reporting a synchronous batch of metric
+// values. Instances of this type should be created by synchronous
+// instruments (e.g., Int64Counter.Measurement()).
+type Measurement struct {
+	// number needs to be aligned for 64-bit atomic operations.
+	number     Number
+	instrument SyncImpl
+}
+
+// syncInstrument contains a SyncImpl.
+type syncInstrument struct {
+	instrument SyncImpl
+}
+
+// syncBoundInstrument contains a BoundSyncImpl.
+type syncBoundInstrument struct {
+	boundInstrument BoundSyncImpl
+}
+
+// asyncInstrument contains a AsyncImpl.
+type asyncInstrument struct {
+	instrument AsyncImpl
+}
+
+// SyncImpl returns the instrument that created this measurement.
+// This returns an implementation-level object for use by the SDK,
+// users should not refer to this.
+func (m Measurement) SyncImpl() SyncImpl {
+	return m.instrument
+}
+
+// Number returns a number recorded in this measurement.
+func (m Measurement) Number() Number {
+	return m.number
+}
+
+// AsyncImpl returns the instrument that created this observation.
+// This returns an implementation-level object for use by the SDK,
+// users should not refer to this.
+func (m Observation) AsyncImpl() AsyncImpl {
+	return m.instrument
+}
+
+// Number returns a number recorded in this observation.
+func (m Observation) Number() Number {
+	return m.number
+}
+
+// AsyncImpl implements AsyncImpl.
+func (a asyncInstrument) AsyncImpl() AsyncImpl {
+	return a.instrument
+}
+
+// SyncImpl returns the implementation object for synchronous instruments.
+func (s syncInstrument) SyncImpl() SyncImpl {
+	return s.instrument
+}
+
+func (s syncInstrument) bind(labels []label.KeyValue) syncBoundInstrument {
+	return newSyncBoundInstrument(s.instrument.Bind(labels))
+}
+
+func (s syncInstrument) float64Measurement(value float64) Measurement {
+	return newMeasurement(s.instrument, NewFloat64Number(value))
+}
+
+func (s syncInstrument) int64Measurement(value int64) Measurement {
+	return newMeasurement(s.instrument, NewInt64Number(value))
+}
+
+func (s syncInstrument) directRecord(ctx context.Context, number Number, labels []label.KeyValue) {
+	s.instrument.RecordOne(ctx, number, labels)
+}
+
+func (h syncBoundInstrument) directRecord(ctx context.Context, number Number) {
+	h.boundInstrument.RecordOne(ctx, number)
+}
+
+// Unbind calls SyncImpl.Unbind.
+func (h syncBoundInstrument) Unbind() {
+	h.boundInstrument.Unbind()
+}
+
+// checkNewAsync receives an AsyncImpl and potential
+// error, and returns the same types, checking for and ensuring that
+// the returned interface is not nil.
+func checkNewAsync(instrument AsyncImpl, err error) (asyncInstrument, error) {
+	if instrument == nil {
+		if err == nil {
+			err = ErrSDKReturnedNilImpl
+		}
+		instrument = NoopAsync{}
+	}
+	return asyncInstrument{
+		instrument: instrument,
+	}, err
+}
+
+// checkNewSync receives an SyncImpl and potential
+// error, and returns the same types, checking for and ensuring that
+// the returned interface is not nil.
+func checkNewSync(instrument SyncImpl, err error) (syncInstrument, error) {
+	if instrument == nil {
+		if err == nil {
+			err = ErrSDKReturnedNilImpl
+		}
+		// Note: an alternate behavior would be to synthesize a new name
+		// or group all duplicately-named instruments of a certain type
+		// together and use a tag for the original name, e.g.,
+		//   name = 'invalid.counter.int64'
+		//   label = 'original-name=duplicate-counter-name'
+		instrument = NoopSync{}
+	}
+	return syncInstrument{
+		instrument: instrument,
+	}, err
+}
+
+func newSyncBoundInstrument(boundInstrument BoundSyncImpl) syncBoundInstrument {
+	return syncBoundInstrument{
+		boundInstrument: boundInstrument,
+	}
+}
+
+func newMeasurement(instrument SyncImpl, number Number) Measurement {
+	return Measurement{
+		instrument: instrument,
+		number:     number,
+	}
+}
+
+// wrapInt64CounterInstrument converts a SyncImpl into Int64Counter.
+func wrapInt64CounterInstrument(syncInst SyncImpl, err error) (Int64Counter, error) {
+	common, err := checkNewSync(syncInst, err)
+	return Int64Counter{syncInstrument: common}, err
+}
+
+// wrapFloat64CounterInstrument converts a SyncImpl into Float64Counter.
+func wrapFloat64CounterInstrument(syncInst SyncImpl, err error) (Float64Counter, error) {
+	common, err := checkNewSync(syncInst, err)
+	return Float64Counter{syncInstrument: common}, err
+}
+
+// wrapInt64UpDownCounterInstrument converts a SyncImpl into Int64UpDownCounter.
+func wrapInt64UpDownCounterInstrument(syncInst SyncImpl, err error) (Int64UpDownCounter, error) {
+	common, err := checkNewSync(syncInst, err)
+	return Int64UpDownCounter{syncInstrument: common}, err
+}
+
+// wrapFloat64UpDownCounterInstrument converts a SyncImpl into Float64UpDownCounter.
+func wrapFloat64UpDownCounterInstrument(syncInst SyncImpl, err error) (Float64UpDownCounter, error) {
+	common, err := checkNewSync(syncInst, err)
+	return Float64UpDownCounter{syncInstrument: common}, err
+}
+
+// wrapInt64ValueRecorderInstrument converts a SyncImpl into Int64ValueRecorder.
+func wrapInt64ValueRecorderInstrument(syncInst SyncImpl, err error) (Int64ValueRecorder, error) {
+	common, err := checkNewSync(syncInst, err)
+	return Int64ValueRecorder{syncInstrument: common}, err
+}
+
+// wrapFloat64ValueRecorderInstrument converts a SyncImpl into Float64ValueRecorder.
+func wrapFloat64ValueRecorderInstrument(syncInst SyncImpl, err error) (Float64ValueRecorder, error) {
+	common, err := checkNewSync(syncInst, err)
+	return Float64ValueRecorder{syncInstrument: common}, err
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/updowncounter.go b/vendor/go.opentelemetry.io/otel/api/metric/updowncounter.go
new file mode 100644
index 0000000..1018246
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/updowncounter.go
@@ -0,0 +1,96 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/label"
+)
+
+// Float64UpDownCounter is a metric instrument that sums floating
+// point values.
+type Float64UpDownCounter struct {
+	syncInstrument
+}
+
+// Int64UpDownCounter is a metric instrument that sums integer values.
+type Int64UpDownCounter struct {
+	syncInstrument
+}
+
+// BoundFloat64UpDownCounter is a bound instrument for Float64UpDownCounter.
+//
+// It inherits the Unbind function from syncBoundInstrument.
+type BoundFloat64UpDownCounter struct {
+	syncBoundInstrument
+}
+
+// BoundInt64UpDownCounter is a boundInstrument for Int64UpDownCounter.
+//
+// It inherits the Unbind function from syncBoundInstrument.
+type BoundInt64UpDownCounter struct {
+	syncBoundInstrument
+}
+
+// Bind creates a bound instrument for this counter. The labels are
+// associated with values recorded via subsequent calls to Record.
+func (c Float64UpDownCounter) Bind(labels ...label.KeyValue) (h BoundFloat64UpDownCounter) {
+	h.syncBoundInstrument = c.bind(labels)
+	return
+}
+
+// Bind creates a bound instrument for this counter. The labels are
+// associated with values recorded via subsequent calls to Record.
+func (c Int64UpDownCounter) Bind(labels ...label.KeyValue) (h BoundInt64UpDownCounter) {
+	h.syncBoundInstrument = c.bind(labels)
+	return
+}
+
+// Measurement creates a Measurement object to use with batch
+// recording.
+func (c Float64UpDownCounter) Measurement(value float64) Measurement {
+	return c.float64Measurement(value)
+}
+
+// Measurement creates a Measurement object to use with batch
+// recording.
+func (c Int64UpDownCounter) Measurement(value int64) Measurement {
+	return c.int64Measurement(value)
+}
+
+// Add adds the value to the counter's sum. The labels should contain
+// the keys and values to be associated with this value.
+func (c Float64UpDownCounter) Add(ctx context.Context, value float64, labels ...label.KeyValue) {
+	c.directRecord(ctx, NewFloat64Number(value), labels)
+}
+
+// Add adds the value to the counter's sum. The labels should contain
+// the keys and values to be associated with this value.
+func (c Int64UpDownCounter) Add(ctx context.Context, value int64, labels ...label.KeyValue) {
+	c.directRecord(ctx, NewInt64Number(value), labels)
+}
+
+// Add adds the value to the counter's sum using the labels
+// previously bound to this counter via Bind()
+func (b BoundFloat64UpDownCounter) Add(ctx context.Context, value float64) {
+	b.directRecord(ctx, NewFloat64Number(value))
+}
+
+// Add adds the value to the counter's sum using the labels
+// previously bound to this counter via Bind()
+func (b BoundInt64UpDownCounter) Add(ctx context.Context, value int64) {
+	b.directRecord(ctx, NewInt64Number(value))
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/metric/valuerecorder.go b/vendor/go.opentelemetry.io/otel/api/metric/valuerecorder.go
new file mode 100644
index 0000000..fa7e2d4
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/metric/valuerecorder.go
@@ -0,0 +1,97 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/label"
+)
+
+// Float64ValueRecorder is a metric that records float64 values.
+type Float64ValueRecorder struct {
+	syncInstrument
+}
+
+// Int64ValueRecorder is a metric that records int64 values.
+type Int64ValueRecorder struct {
+	syncInstrument
+}
+
+// BoundFloat64ValueRecorder is a bound instrument for Float64ValueRecorder.
+//
+// It inherits the Unbind function from syncBoundInstrument.
+type BoundFloat64ValueRecorder struct {
+	syncBoundInstrument
+}
+
+// BoundInt64ValueRecorder is a bound instrument for Int64ValueRecorder.
+//
+// It inherits the Unbind function from syncBoundInstrument.
+type BoundInt64ValueRecorder struct {
+	syncBoundInstrument
+}
+
+// Bind creates a bound instrument for this ValueRecorder. The labels are
+// associated with values recorded via subsequent calls to Record.
+func (c Float64ValueRecorder) Bind(labels ...label.KeyValue) (h BoundFloat64ValueRecorder) {
+	h.syncBoundInstrument = c.bind(labels)
+	return
+}
+
+// Bind creates a bound instrument for this ValueRecorder. The labels are
+// associated with values recorded via subsequent calls to Record.
+func (c Int64ValueRecorder) Bind(labels ...label.KeyValue) (h BoundInt64ValueRecorder) {
+	h.syncBoundInstrument = c.bind(labels)
+	return
+}
+
+// Measurement creates a Measurement object to use with batch
+// recording.
+func (c Float64ValueRecorder) Measurement(value float64) Measurement {
+	return c.float64Measurement(value)
+}
+
+// Measurement creates a Measurement object to use with batch
+// recording.
+func (c Int64ValueRecorder) Measurement(value int64) Measurement {
+	return c.int64Measurement(value)
+}
+
+// Record adds a new value to the list of ValueRecorder's records. The
+// labels should contain the keys and values to be associated with
+// this value.
+func (c Float64ValueRecorder) Record(ctx context.Context, value float64, labels ...label.KeyValue) {
+	c.directRecord(ctx, NewFloat64Number(value), labels)
+}
+
+// Record adds a new value to the ValueRecorder's distribution. The
+// labels should contain the keys and values to be associated with
+// this value.
+func (c Int64ValueRecorder) Record(ctx context.Context, value int64, labels ...label.KeyValue) {
+	c.directRecord(ctx, NewInt64Number(value), labels)
+}
+
+// Record adds a new value to the ValueRecorder's distribution using the labels
+// previously bound to the ValueRecorder via Bind().
+func (b BoundFloat64ValueRecorder) Record(ctx context.Context, value float64) {
+	b.directRecord(ctx, NewFloat64Number(value))
+}
+
+// Record adds a new value to the ValueRecorder's distribution using the labels
+// previously bound to the ValueRecorder via Bind().
+func (b BoundInt64ValueRecorder) Record(ctx context.Context, value int64) {
+	b.directRecord(ctx, NewInt64Number(value))
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/trace/api.go b/vendor/go.opentelemetry.io/otel/api/trace/api.go
new file mode 100644
index 0000000..3f15f48
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/trace/api.go
@@ -0,0 +1,314 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace
+
+import (
+	"context"
+	"time"
+
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/label"
+)
+
+// TracerProvider provides access to instrumentation Tracers.
+type TracerProvider interface {
+	// Tracer creates an implementation of the Tracer interface.
+	// The instrumentationName must be the name of the library providing
+	// instrumentation. This name may be the same as the instrumented code
+	// only if that code provides built-in instrumentation. If the
+	// instrumentationName is empty, then a implementation defined default
+	// name will be used instead.
+	Tracer(instrumentationName string, opts ...TracerOption) Tracer
+}
+
+// TracerConfig is a group of options for a Tracer.
+//
+// Most users will use the tracer options instead.
+type TracerConfig struct {
+	// InstrumentationVersion is the version of the instrumentation library.
+	InstrumentationVersion string
+}
+
+// NewTracerConfig applies all the options to a returned TracerConfig.
+// The default value for all the fields of the returned TracerConfig are the
+// default zero value of the type. Also, this does not perform any validation
+// on the returned TracerConfig (e.g. no uniqueness checking or bounding of
+// data), instead it is left to the implementations of the SDK to perform this
+// action.
+func NewTracerConfig(opts ...TracerOption) *TracerConfig {
+	config := new(TracerConfig)
+	for _, option := range opts {
+		option.Apply(config)
+	}
+	return config
+}
+
+// TracerOption applies an options to a TracerConfig.
+type TracerOption interface {
+	Apply(*TracerConfig)
+}
+
+type instVersionTracerOption string
+
+func (o instVersionTracerOption) Apply(c *TracerConfig) { c.InstrumentationVersion = string(o) }
+
+// WithInstrumentationVersion sets the instrumentation version for a Tracer.
+func WithInstrumentationVersion(version string) TracerOption {
+	return instVersionTracerOption(version)
+}
+
+type Tracer interface {
+	// Start a span.
+	Start(ctx context.Context, spanName string, opts ...SpanOption) (context.Context, Span)
+}
+
+// ErrorConfig provides options to set properties of an error
+// event at the time it is recorded.
+//
+// Most users will use the error options instead.
+type ErrorConfig struct {
+	Timestamp  time.Time
+	StatusCode codes.Code
+}
+
+// ErrorOption applies changes to ErrorConfig that sets options when an error event is recorded.
+type ErrorOption func(*ErrorConfig)
+
+// WithErrorTime sets the time at which the error event should be recorded.
+func WithErrorTime(t time.Time) ErrorOption {
+	return func(c *ErrorConfig) {
+		c.Timestamp = t
+	}
+}
+
+// WithErrorStatus indicates the span status that should be set when recording an error event.
+func WithErrorStatus(s codes.Code) ErrorOption {
+	return func(c *ErrorConfig) {
+		c.StatusCode = s
+	}
+}
+
+type Span interface {
+	// Tracer returns tracer used to create this span. Tracer cannot be nil.
+	Tracer() Tracer
+
+	// End completes the span. No updates are allowed to span after it
+	// ends. The only exception is setting status of the span.
+	End(options ...SpanOption)
+
+	// AddEvent adds an event to the span.
+	AddEvent(ctx context.Context, name string, attrs ...label.KeyValue)
+	// AddEventWithTimestamp adds an event with a custom timestamp
+	// to the span.
+	AddEventWithTimestamp(ctx context.Context, timestamp time.Time, name string, attrs ...label.KeyValue)
+
+	// IsRecording returns true if the span is active and recording events is enabled.
+	IsRecording() bool
+
+	// RecordError records an error as a span event.
+	RecordError(ctx context.Context, err error, opts ...ErrorOption)
+
+	// SpanContext returns span context of the span. Returned SpanContext is usable
+	// even after the span ends.
+	SpanContext() SpanContext
+
+	// SetStatus sets the status of the span in the form of a code
+	// and a message.  SetStatus overrides the value of previous
+	// calls to SetStatus on the Span.
+	//
+	// The default span status is OK, so it is not necessary to
+	// explicitly set an OK status on successful Spans unless it
+	// is to add an OK message or to override a previous status on the Span.
+	SetStatus(code codes.Code, msg string)
+
+	// SetName sets the name of the span.
+	SetName(name string)
+
+	// Set span attributes
+	SetAttributes(kv ...label.KeyValue)
+}
+
+// SpanConfig is a group of options for a Span.
+//
+// Most users will use span options instead.
+type SpanConfig struct {
+	// Attributes describe the associated qualities of a Span.
+	Attributes []label.KeyValue
+	// Timestamp is a time in a Span life-cycle.
+	Timestamp time.Time
+	// Links are the associations a Span has with other Spans.
+	Links []Link
+	// Record is the recording state of a Span.
+	Record bool
+	// NewRoot identifies a Span as the root Span for a new trace. This is
+	// commonly used when an existing trace crosses trust boundaries and the
+	// remote parent span context should be ignored for security.
+	NewRoot bool
+	// SpanKind is the role a Span has in a trace.
+	SpanKind SpanKind
+}
+
+// NewSpanConfig applies all the options to a returned SpanConfig.
+// The default value for all the fields of the returned SpanConfig are the
+// default zero value of the type. Also, this does not perform any validation
+// on the returned SpanConfig (e.g. no uniqueness checking or bounding of
+// data). Instead, it is left to the implementations of the SDK to perform this
+// action.
+func NewSpanConfig(opts ...SpanOption) *SpanConfig {
+	c := new(SpanConfig)
+	for _, option := range opts {
+		option.Apply(c)
+	}
+	return c
+}
+
+// SpanOption applies an option to a SpanConfig.
+type SpanOption interface {
+	Apply(*SpanConfig)
+}
+
+type attributeSpanOption []label.KeyValue
+
+func (o attributeSpanOption) Apply(c *SpanConfig) {
+	c.Attributes = append(c.Attributes, []label.KeyValue(o)...)
+}
+
+// WithAttributes adds the attributes to a span. These attributes are meant to
+// provide additional information about the work the Span represents. The
+// attributes are added to the existing Span attributes, i.e. this does not
+// overwrite.
+func WithAttributes(attributes ...label.KeyValue) SpanOption {
+	return attributeSpanOption(attributes)
+}
+
+type timestampSpanOption time.Time
+
+func (o timestampSpanOption) Apply(c *SpanConfig) { c.Timestamp = time.Time(o) }
+
+// WithTimestamp sets the time of a Span life-cycle moment (e.g. started or
+// stopped).
+func WithTimestamp(t time.Time) SpanOption {
+	return timestampSpanOption(t)
+}
+
+type linksSpanOption []Link
+
+func (o linksSpanOption) Apply(c *SpanConfig) { c.Links = append(c.Links, []Link(o)...) }
+
+// WithLinks adds links to a Span. The links are added to the existing Span
+// links, i.e. this does not overwrite.
+func WithLinks(links ...Link) SpanOption {
+	return linksSpanOption(links)
+}
+
+type recordSpanOption bool
+
+func (o recordSpanOption) Apply(c *SpanConfig) { c.Record = bool(o) }
+
+// WithRecord specifies that the span should be recorded. It is important to
+// note that implementations may override this option, i.e. if the span is a
+// child of an un-sampled trace.
+func WithRecord() SpanOption {
+	return recordSpanOption(true)
+}
+
+type newRootSpanOption bool
+
+func (o newRootSpanOption) Apply(c *SpanConfig) { c.NewRoot = bool(o) }
+
+// WithNewRoot specifies that the Span should be treated as a root Span. Any
+// existing parent span context will be ignored when defining the Span's trace
+// identifiers.
+func WithNewRoot() SpanOption {
+	return newRootSpanOption(true)
+}
+
+type spanKindSpanOption SpanKind
+
+func (o spanKindSpanOption) Apply(c *SpanConfig) { c.SpanKind = SpanKind(o) }
+
+// WithSpanKind sets the SpanKind of a Span.
+func WithSpanKind(kind SpanKind) SpanOption {
+	return spanKindSpanOption(kind)
+}
+
+// Link is used to establish relationship between two spans within the same Trace or
+// across different Traces. Few examples of Link usage.
+//   1. Batch Processing: A batch of elements may contain elements associated with one
+//      or more traces/spans. Since there can only be one parent SpanContext, Link is
+//      used to keep reference to SpanContext of all elements in the batch.
+//   2. Public Endpoint: A SpanContext in incoming client request on a public endpoint
+//      is untrusted from service provider perspective. In such case it is advisable to
+//      start a new trace with appropriate sampling decision.
+//      However, it is desirable to associate incoming SpanContext to new trace initiated
+//      on service provider side so two traces (from Client and from Service Provider) can
+//      be correlated.
+type Link struct {
+	SpanContext
+	Attributes []label.KeyValue
+}
+
+// SpanKind represents the role of a Span inside a Trace. Often, this defines how a Span
+// will be processed and visualized by various backends.
+type SpanKind int
+
+const (
+	// As a convenience, these match the proto definition, see
+	// opentelemetry/proto/trace/v1/trace.proto
+	//
+	// The unspecified value is not a valid `SpanKind`.  Use
+	// `ValidateSpanKind()` to coerce a span kind to a valid
+	// value.
+	SpanKindUnspecified SpanKind = 0
+	SpanKindInternal    SpanKind = 1
+	SpanKindServer      SpanKind = 2
+	SpanKindClient      SpanKind = 3
+	SpanKindProducer    SpanKind = 4
+	SpanKindConsumer    SpanKind = 5
+)
+
+// ValidateSpanKind returns a valid span kind value.  This will coerce
+// invalid values into the default value, SpanKindInternal.
+func ValidateSpanKind(spanKind SpanKind) SpanKind {
+	switch spanKind {
+	case SpanKindInternal,
+		SpanKindServer,
+		SpanKindClient,
+		SpanKindProducer,
+		SpanKindConsumer:
+		// valid
+		return spanKind
+	default:
+		return SpanKindInternal
+	}
+}
+
+// String returns the specified name of the SpanKind in lower-case.
+func (sk SpanKind) String() string {
+	switch sk {
+	case SpanKindInternal:
+		return "internal"
+	case SpanKindServer:
+		return "server"
+	case SpanKindClient:
+		return "client"
+	case SpanKindProducer:
+		return "producer"
+	case SpanKindConsumer:
+		return "consumer"
+	default:
+		return "unspecified"
+	}
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/trace/context.go b/vendor/go.opentelemetry.io/otel/api/trace/context.go
new file mode 100644
index 0000000..0f330e3
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/trace/context.go
@@ -0,0 +1,55 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace
+
+import (
+	"context"
+)
+
+type traceContextKeyType int
+
+const (
+	currentSpanKey traceContextKeyType = iota
+	remoteContextKey
+)
+
+// ContextWithSpan creates a new context with a current span set to
+// the passed span.
+func ContextWithSpan(ctx context.Context, span Span) context.Context {
+	return context.WithValue(ctx, currentSpanKey, span)
+}
+
+// SpanFromContext returns the current span stored in the context.
+func SpanFromContext(ctx context.Context) Span {
+	if span, has := ctx.Value(currentSpanKey).(Span); has {
+		return span
+	}
+	return noopSpan{}
+}
+
+// ContextWithRemoteSpanContext creates a new context with a remote
+// span context set to the passed span context.
+func ContextWithRemoteSpanContext(ctx context.Context, sc SpanContext) context.Context {
+	return context.WithValue(ctx, remoteContextKey, sc)
+}
+
+// RemoteSpanContextFromContext returns the remote span context stored
+// in the context.
+func RemoteSpanContextFromContext(ctx context.Context) SpanContext {
+	if sc, ok := ctx.Value(remoteContextKey).(SpanContext); ok {
+		return sc
+	}
+	return EmptySpanContext()
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/trace/doc.go b/vendor/go.opentelemetry.io/otel/api/trace/doc.go
new file mode 100644
index 0000000..24f2dfb
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/trace/doc.go
@@ -0,0 +1,16 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package trace provides tracing support.
+package trace // import "go.opentelemetry.io/otel/api/trace"
diff --git a/vendor/go.opentelemetry.io/otel/api/trace/noop_span.go b/vendor/go.opentelemetry.io/otel/api/trace/noop_span.go
new file mode 100644
index 0000000..f014f21
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/trace/noop_span.go
@@ -0,0 +1,75 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace
+
+import (
+	"context"
+	"time"
+
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/label"
+)
+
+type noopSpan struct {
+}
+
+var _ Span = noopSpan{}
+
+// SpanContext returns an invalid span context.
+func (noopSpan) SpanContext() SpanContext {
+	return EmptySpanContext()
+}
+
+// IsRecording always returns false for NoopSpan.
+func (noopSpan) IsRecording() bool {
+	return false
+}
+
+// SetStatus does nothing.
+func (noopSpan) SetStatus(status codes.Code, msg string) {
+}
+
+// SetError does nothing.
+func (noopSpan) SetError(v bool) {
+}
+
+// SetAttributes does nothing.
+func (noopSpan) SetAttributes(attributes ...label.KeyValue) {
+}
+
+// End does nothing.
+func (noopSpan) End(options ...SpanOption) {
+}
+
+// RecordError does nothing.
+func (noopSpan) RecordError(ctx context.Context, err error, opts ...ErrorOption) {
+}
+
+// Tracer returns noop implementation of Tracer.
+func (noopSpan) Tracer() Tracer {
+	return noopTracer{}
+}
+
+// AddEvent does nothing.
+func (noopSpan) AddEvent(ctx context.Context, name string, attrs ...label.KeyValue) {
+}
+
+// AddEventWithTimestamp does nothing.
+func (noopSpan) AddEventWithTimestamp(ctx context.Context, timestamp time.Time, name string, attrs ...label.KeyValue) {
+}
+
+// SetName does nothing.
+func (noopSpan) SetName(name string) {
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/trace/noop_trace.go b/vendor/go.opentelemetry.io/otel/api/trace/noop_trace.go
new file mode 100644
index 0000000..954f9e8
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/trace/noop_trace.go
@@ -0,0 +1,29 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace
+
+import (
+	"context"
+)
+
+type noopTracer struct{}
+
+var _ Tracer = noopTracer{}
+
+// Start starts a noop span.
+func (noopTracer) Start(ctx context.Context, name string, opts ...SpanOption) (context.Context, Span) {
+	span := noopSpan{}
+	return ContextWithSpan(ctx, span), span
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/trace/noop_trace_provider.go b/vendor/go.opentelemetry.io/otel/api/trace/noop_trace_provider.go
new file mode 100644
index 0000000..414c8e3
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/trace/noop_trace_provider.go
@@ -0,0 +1,30 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace
+
+type noopTracerProvider struct{}
+
+var _ TracerProvider = noopTracerProvider{}
+
+// Tracer returns noop implementation of Tracer.
+func (p noopTracerProvider) Tracer(_ string, _ ...TracerOption) Tracer {
+	return noopTracer{}
+}
+
+// NoopTracerProvider returns a noop implementation of TracerProvider. The
+// Tracer and Spans created from the noop provider will also be noop.
+func NoopTracerProvider() TracerProvider {
+	return noopTracerProvider{}
+}
diff --git a/vendor/go.opentelemetry.io/otel/api/trace/span_context.go b/vendor/go.opentelemetry.io/otel/api/trace/span_context.go
new file mode 100644
index 0000000..914ce5f
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/api/trace/span_context.go
@@ -0,0 +1,197 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace
+
+import (
+	"bytes"
+	"encoding/hex"
+	"encoding/json"
+)
+
+const (
+	// FlagsSampled is a bitmask with the sampled bit set. A SpanContext
+	// with the sampling bit set means the span is sampled.
+	FlagsSampled = byte(0x01)
+	// FlagsDeferred is a bitmask with the deferred bit set. A SpanContext
+	// with the deferred bit set means the sampling decision has been
+	// defered to the receiver.
+	FlagsDeferred = byte(0x02)
+	// FlagsDebug is a bitmask with the debug bit set.
+	FlagsDebug = byte(0x04)
+
+	ErrInvalidHexID errorConst = "trace-id and span-id can only contain [0-9a-f] characters, all lowercase"
+
+	ErrInvalidTraceIDLength errorConst = "hex encoded trace-id must have length equals to 32"
+	ErrNilTraceID           errorConst = "trace-id can't be all zero"
+
+	ErrInvalidSpanIDLength errorConst = "hex encoded span-id must have length equals to 16"
+	ErrNilSpanID           errorConst = "span-id can't be all zero"
+)
+
+type errorConst string
+
+func (e errorConst) Error() string {
+	return string(e)
+}
+
+// ID is a unique identity of a trace.
+type ID [16]byte
+
+var nilTraceID ID
+var _ json.Marshaler = nilTraceID
+
+// IsValid checks whether the trace ID is valid. A valid trace ID does
+// not consist of zeros only.
+func (t ID) IsValid() bool {
+	return !bytes.Equal(t[:], nilTraceID[:])
+}
+
+// MarshalJSON implements a custom marshal function to encode TraceID
+// as a hex string.
+func (t ID) MarshalJSON() ([]byte, error) {
+	return json.Marshal(t.String())
+}
+
+// String returns the hex string representation form of a TraceID
+func (t ID) String() string {
+	return hex.EncodeToString(t[:])
+}
+
+// SpanID is a unique identify of a span in a trace.
+type SpanID [8]byte
+
+var nilSpanID SpanID
+var _ json.Marshaler = nilSpanID
+
+// IsValid checks whether the span ID is valid. A valid span ID does
+// not consist of zeros only.
+func (s SpanID) IsValid() bool {
+	return !bytes.Equal(s[:], nilSpanID[:])
+}
+
+// MarshalJSON implements a custom marshal function to encode SpanID
+// as a hex string.
+func (s SpanID) MarshalJSON() ([]byte, error) {
+	return json.Marshal(s.String())
+}
+
+// String returns the hex string representation form of a SpanID
+func (s SpanID) String() string {
+	return hex.EncodeToString(s[:])
+}
+
+// IDFromHex returns a TraceID from a hex string if it is compliant
+// with the w3c trace-context specification.
+// See more at https://www.w3.org/TR/trace-context/#trace-id
+func IDFromHex(h string) (ID, error) {
+	t := ID{}
+	if len(h) != 32 {
+		return t, ErrInvalidTraceIDLength
+	}
+
+	if err := decodeHex(h, t[:]); err != nil {
+		return t, err
+	}
+
+	if !t.IsValid() {
+		return t, ErrNilTraceID
+	}
+	return t, nil
+}
+
+// SpanIDFromHex returns a SpanID from a hex string if it is compliant
+// with the w3c trace-context specification.
+// See more at https://www.w3.org/TR/trace-context/#parent-id
+func SpanIDFromHex(h string) (SpanID, error) {
+	s := SpanID{}
+	if len(h) != 16 {
+		return s, ErrInvalidSpanIDLength
+	}
+
+	if err := decodeHex(h, s[:]); err != nil {
+		return s, err
+	}
+
+	if !s.IsValid() {
+		return s, ErrNilSpanID
+	}
+	return s, nil
+}
+
+func decodeHex(h string, b []byte) error {
+	for _, r := range h {
+		switch {
+		case 'a' <= r && r <= 'f':
+			continue
+		case '0' <= r && r <= '9':
+			continue
+		default:
+			return ErrInvalidHexID
+		}
+	}
+
+	decoded, err := hex.DecodeString(h)
+	if err != nil {
+		return err
+	}
+
+	copy(b, decoded)
+	return nil
+}
+
+// SpanContext contains basic information about the span - its trace
+// ID, span ID and trace flags.
+type SpanContext struct {
+	TraceID    ID
+	SpanID     SpanID
+	TraceFlags byte
+}
+
+// EmptySpanContext is meant for internal use to return invalid span
+// context during error conditions.
+func EmptySpanContext() SpanContext {
+	return SpanContext{}
+}
+
+// IsValid checks if the span context is valid. A valid span context
+// has a valid trace ID and a valid span ID.
+func (sc SpanContext) IsValid() bool {
+	return sc.HasTraceID() && sc.HasSpanID()
+}
+
+// HasTraceID checks if the span context has a valid trace ID.
+func (sc SpanContext) HasTraceID() bool {
+	return sc.TraceID.IsValid()
+}
+
+// HasSpanID checks if the span context has a valid span ID.
+func (sc SpanContext) HasSpanID() bool {
+	return sc.SpanID.IsValid()
+}
+
+// IsDeferred returns if the deferred bit is set in the trace flags.
+func (sc SpanContext) IsDeferred() bool {
+	return sc.TraceFlags&FlagsDeferred == FlagsDeferred
+}
+
+// IsDebug returns if the debug bit is set in the trace flags.
+func (sc SpanContext) IsDebug() bool {
+	return sc.TraceFlags&FlagsDebug == FlagsDebug
+}
+
+// IsSampled returns if the sampling bit is set in the trace flags.
+func (sc SpanContext) IsSampled() bool {
+	return sc.TraceFlags&FlagsSampled == FlagsSampled
+}
diff --git a/vendor/go.opentelemetry.io/otel/baggage.go b/vendor/go.opentelemetry.io/otel/baggage.go
new file mode 100644
index 0000000..bf0f1f6
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/baggage.go
@@ -0,0 +1,67 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package otel
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/internal/baggage"
+	"go.opentelemetry.io/otel/label"
+)
+
+// Baggage returns a copy of the baggage in ctx.
+func Baggage(ctx context.Context) label.Set {
+	// TODO (MrAlias, #1222): The underlying storage, the Map, shares many of
+	// the functional elements of the label.Set. These should be unified so
+	// this conversion is unnecessary and there is no performance hit calling
+	// this.
+	m := baggage.MapFromContext(ctx)
+	values := make([]label.KeyValue, 0, m.Len())
+	m.Foreach(func(kv label.KeyValue) bool {
+		values = append(values, kv)
+		return true
+	})
+	return label.NewSet(values...)
+}
+
+// BaggageValue returns the value related to key in the baggage of ctx. If no
+// value is set, the returned label.Value will be an uninitialized zero-value
+// with type INVALID.
+func BaggageValue(ctx context.Context, key label.Key) label.Value {
+	v, _ := baggage.MapFromContext(ctx).Value(key)
+	return v
+}
+
+// ContextWithBaggageValues returns a copy of parent with pairs updated in the baggage.
+func ContextWithBaggageValues(parent context.Context, pairs ...label.KeyValue) context.Context {
+	m := baggage.MapFromContext(parent).Apply(baggage.MapUpdate{
+		MultiKV: pairs,
+	})
+	return baggage.ContextWithMap(parent, m)
+}
+
+// ContextWithoutBaggageValues returns a copy of parent in which the values related
+// to keys have been removed from the baggage.
+func ContextWithoutBaggageValues(parent context.Context, keys ...label.Key) context.Context {
+	m := baggage.MapFromContext(parent).Apply(baggage.MapUpdate{
+		DropMultiK: keys,
+	})
+	return baggage.ContextWithMap(parent, m)
+}
+
+// ContextWithoutBaggage returns a copy of parent without baggage.
+func ContextWithoutBaggage(parent context.Context) context.Context {
+	return baggage.ContextWithNoCorrelationData(parent)
+}
diff --git a/vendor/go.opentelemetry.io/otel/codes/codes.go b/vendor/go.opentelemetry.io/otel/codes/codes.go
new file mode 100644
index 0000000..28393a5
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/codes/codes.go
@@ -0,0 +1,99 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package codes defines the canonical error codes used by OpenTelemetry.
+//
+// It conforms to [the OpenTelemetry
+// specification](https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/trace/api.md#statuscanonicalcode).
+package codes // import "go.opentelemetry.io/otel/codes"
+
+import (
+	"fmt"
+	"strconv"
+)
+
+const (
+	// Unset is the default status code.
+	Unset Code = 0
+	// Error indicates the operation contains an error.
+	Error Code = 1
+	// Ok indicates operation has been validated by an Application developers
+	// or Operator to have completed successfully, or contain no error.
+	Ok Code = 2
+
+	maxCode = 3
+)
+
+// Code is an 32-bit representation of a status state.
+type Code uint32
+
+var codeToStr = map[Code]string{
+	Unset: "Unset",
+	Error: "Error",
+	Ok:    "Ok",
+}
+
+var strToCode = map[string]Code{
+	"Unset": Unset,
+	"Error": Error,
+	"Ok":    Ok,
+}
+
+// String returns the Code as a string.
+func (c Code) String() string {
+	return codeToStr[c]
+}
+
+// UnmarshalJSON unmarshals b into the Code.
+//
+// This is based on the functionality in the gRPC codes package:
+// https://github.com/grpc/grpc-go/blob/bb64fee312b46ebee26be43364a7a966033521b1/codes/codes.go#L218-L244
+func (c *Code) UnmarshalJSON(b []byte) error {
+	// From json.Unmarshaler: By convention, to approximate the behavior of
+	// Unmarshal itself, Unmarshalers implement UnmarshalJSON([]byte("null")) as
+	// a no-op.
+	if string(b) == "null" {
+		return nil
+	}
+	if c == nil {
+		return fmt.Errorf("nil receiver passed to UnmarshalJSON")
+	}
+
+	if ci, err := strconv.ParseUint(string(b), 10, 32); err == nil {
+		if ci >= maxCode {
+			return fmt.Errorf("invalid code: %q", ci)
+		}
+
+		*c = Code(ci)
+		return nil
+	}
+
+	if jc, ok := strToCode[string(b)]; ok {
+		*c = jc
+		return nil
+	}
+	return fmt.Errorf("invalid code: %q", string(b))
+}
+
+// MarshalJSON returns c as the JSON encoding of c.
+func (c *Code) MarshalJSON() ([]byte, error) {
+	if c == nil {
+		return []byte("null"), nil
+	}
+	str, ok := codeToStr[*c]
+	if !ok {
+		return nil, fmt.Errorf("invalid code: %d", *c)
+	}
+	return []byte(fmt.Sprintf("%q", str)), nil
+}
diff --git a/vendor/go.opentelemetry.io/otel/doc.go b/vendor/go.opentelemetry.io/otel/doc.go
new file mode 100644
index 0000000..de2f76c
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/doc.go
@@ -0,0 +1,16 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package otel contains OpenTelemetry Go packages.
+package otel // import "go.opentelemetry.io/otel"
diff --git a/vendor/go.opentelemetry.io/otel/get_main_pkgs.sh b/vendor/go.opentelemetry.io/otel/get_main_pkgs.sh
new file mode 100644
index 0000000..d1c892f
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/get_main_pkgs.sh
@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -euo pipefail
+
+top_dir='.'
+if [[ $# -gt 0 ]]; then
+    top_dir="${1}"
+fi
+
+p=$(pwd)
+mod_dirs=()
+mapfile -t mod_dirs < <(find "${top_dir}" -type f -name 'go.mod' -exec dirname {} \; | sort)
+
+for mod_dir in "${mod_dirs[@]}"; do
+    cd "${mod_dir}"
+    main_dirs=()
+    mapfile -t main_dirs < <(go list --find -f '{{.Name}}|{{.Dir}}' ./... | grep '^main|' | cut -f 2- -d '|')
+    for main_dir in "${main_dirs[@]}"; do
+        echo ".${main_dir#${p}}"
+    done
+    cd "${p}"
+done
diff --git a/vendor/go.opentelemetry.io/otel/go.mod b/vendor/go.opentelemetry.io/otel/go.mod
new file mode 100644
index 0000000..95f9aa4
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/go.mod
@@ -0,0 +1,8 @@
+module go.opentelemetry.io/otel
+
+go 1.14
+
+require (
+	github.com/google/go-cmp v0.5.2
+	github.com/stretchr/testify v1.6.1
+)
diff --git a/vendor/go.opentelemetry.io/otel/go.sum b/vendor/go.opentelemetry.io/otel/go.sum
new file mode 100644
index 0000000..bf1148d
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/go.sum
@@ -0,0 +1,15 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/go-cmp v0.5.2 h1:X2ev0eStA3AbceY54o37/0PQ/UWqKEiiO2dKL5OPaFM=
+github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/vendor/go.opentelemetry.io/otel/internal/baggage/baggage.go b/vendor/go.opentelemetry.io/otel/internal/baggage/baggage.go
new file mode 100644
index 0000000..6b5c0c2
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/internal/baggage/baggage.go
@@ -0,0 +1,338 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package baggage provides types and functions to manage W3C Baggage.
+package baggage
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/label"
+)
+
+type rawMap map[label.Key]label.Value
+type keySet map[label.Key]struct{}
+
+// Map is an immutable storage for correlations.
+type Map struct {
+	m rawMap
+}
+
+// MapUpdate contains information about correlation changes to be
+// made.
+type MapUpdate struct {
+	// DropSingleK contains a single key to be dropped from
+	// correlations. Use this to avoid an overhead of a slice
+	// allocation if there is only one key to drop.
+	DropSingleK label.Key
+	// DropMultiK contains all the keys to be dropped from
+	// correlations.
+	DropMultiK []label.Key
+
+	// SingleKV contains a single key-value pair to be added to
+	// correlations. Use this to avoid an overhead of a slice
+	// allocation if there is only one key-value pair to add.
+	SingleKV label.KeyValue
+	// MultiKV contains all the key-value pairs to be added to
+	// correlations.
+	MultiKV []label.KeyValue
+}
+
+func newMap(raw rawMap) Map {
+	return Map{
+		m: raw,
+	}
+}
+
+// NewEmptyMap creates an empty correlations map.
+func NewEmptyMap() Map {
+	return newMap(nil)
+}
+
+// NewMap creates a map with the contents of the update applied. In
+// this function, having an update with DropSingleK or DropMultiK
+// makes no sense - those fields are effectively ignored.
+func NewMap(update MapUpdate) Map {
+	return NewEmptyMap().Apply(update)
+}
+
+// Apply creates a copy of the map with the contents of the update
+// applied. Apply will first drop the keys from DropSingleK and
+// DropMultiK, then add key-value pairs from SingleKV and MultiKV.
+func (m Map) Apply(update MapUpdate) Map {
+	delSet, addSet := getModificationSets(update)
+	mapSize := getNewMapSize(m.m, delSet, addSet)
+
+	r := make(rawMap, mapSize)
+	for k, v := range m.m {
+		// do not copy items we want to drop
+		if _, ok := delSet[k]; ok {
+			continue
+		}
+		// do not copy items we would overwrite
+		if _, ok := addSet[k]; ok {
+			continue
+		}
+		r[k] = v
+	}
+	if update.SingleKV.Key.Defined() {
+		r[update.SingleKV.Key] = update.SingleKV.Value
+	}
+	for _, kv := range update.MultiKV {
+		r[kv.Key] = kv.Value
+	}
+	if len(r) == 0 {
+		r = nil
+	}
+	return newMap(r)
+}
+
+func getModificationSets(update MapUpdate) (delSet, addSet keySet) {
+	deletionsCount := len(update.DropMultiK)
+	if update.DropSingleK.Defined() {
+		deletionsCount++
+	}
+	if deletionsCount > 0 {
+		delSet = make(map[label.Key]struct{}, deletionsCount)
+		for _, k := range update.DropMultiK {
+			delSet[k] = struct{}{}
+		}
+		if update.DropSingleK.Defined() {
+			delSet[update.DropSingleK] = struct{}{}
+		}
+	}
+
+	additionsCount := len(update.MultiKV)
+	if update.SingleKV.Key.Defined() {
+		additionsCount++
+	}
+	if additionsCount > 0 {
+		addSet = make(map[label.Key]struct{}, additionsCount)
+		for _, k := range update.MultiKV {
+			addSet[k.Key] = struct{}{}
+		}
+		if update.SingleKV.Key.Defined() {
+			addSet[update.SingleKV.Key] = struct{}{}
+		}
+	}
+
+	return
+}
+
+func getNewMapSize(m rawMap, delSet, addSet keySet) int {
+	mapSizeDiff := 0
+	for k := range addSet {
+		if _, ok := m[k]; !ok {
+			mapSizeDiff++
+		}
+	}
+	for k := range delSet {
+		if _, ok := m[k]; ok {
+			if _, inAddSet := addSet[k]; !inAddSet {
+				mapSizeDiff--
+			}
+		}
+	}
+	return len(m) + mapSizeDiff
+}
+
+// Value gets a value from correlations map and returns a boolean
+// value indicating whether the key exist in the map.
+func (m Map) Value(k label.Key) (label.Value, bool) {
+	value, ok := m.m[k]
+	return value, ok
+}
+
+// HasValue returns a boolean value indicating whether the key exist
+// in the map.
+func (m Map) HasValue(k label.Key) bool {
+	_, has := m.Value(k)
+	return has
+}
+
+// Len returns a length of the map.
+func (m Map) Len() int {
+	return len(m.m)
+}
+
+// Foreach calls a passed callback once on each key-value pair until
+// all the key-value pairs of the map were iterated or the callback
+// returns false, whichever happens first.
+func (m Map) Foreach(f func(label.KeyValue) bool) {
+	for k, v := range m.m {
+		if !f(label.KeyValue{
+			Key:   k,
+			Value: v,
+		}) {
+			return
+		}
+	}
+}
+
+type correlationsType struct{}
+
+// SetHookFunc describes a type of a callback that is called when
+// storing baggage in the context.
+type SetHookFunc func(context.Context) context.Context
+
+// GetHookFunc describes a type of a callback that is called when
+// getting baggage from the context.
+type GetHookFunc func(context.Context, Map) Map
+
+// value under this key is either of type Map or correlationsData
+var correlationsKey = &correlationsType{}
+
+type correlationsData struct {
+	m       Map
+	setHook SetHookFunc
+	getHook GetHookFunc
+}
+
+func (d correlationsData) isHookless() bool {
+	return d.setHook == nil && d.getHook == nil
+}
+
+type hookKind int
+
+const (
+	hookKindSet hookKind = iota
+	hookKindGet
+)
+
+func (d *correlationsData) overrideHook(kind hookKind, setHook SetHookFunc, getHook GetHookFunc) {
+	switch kind {
+	case hookKindSet:
+		d.setHook = setHook
+	case hookKindGet:
+		d.getHook = getHook
+	}
+}
+
+// ContextWithSetHook installs a hook function that will be invoked
+// every time ContextWithMap is called. To avoid unnecessary callback
+// invocations (recursive or not), the callback can temporarily clear
+// the hooks from the context with the ContextWithNoHooks function.
+//
+// Note that NewContext also calls ContextWithMap, so the hook will be
+// invoked.
+//
+// Passing nil SetHookFunc creates a context with no set hook to call.
+//
+// This function should not be used by applications or libraries. It
+// is mostly for interoperation with other observability APIs.
+func ContextWithSetHook(ctx context.Context, hook SetHookFunc) context.Context {
+	return contextWithHook(ctx, hookKindSet, hook, nil)
+}
+
+// ContextWithGetHook installs a hook function that will be invoked
+// every time MapFromContext is called. To avoid unnecessary callback
+// invocations (recursive or not), the callback can temporarily clear
+// the hooks from the context with the ContextWithNoHooks function.
+//
+// Note that NewContext also calls MapFromContext, so the hook will be
+// invoked.
+//
+// Passing nil GetHookFunc creates a context with no get hook to call.
+//
+// This function should not be used by applications or libraries. It
+// is mostly for interoperation with other observability APIs.
+func ContextWithGetHook(ctx context.Context, hook GetHookFunc) context.Context {
+	return contextWithHook(ctx, hookKindGet, nil, hook)
+}
+
+func contextWithHook(ctx context.Context, kind hookKind, setHook SetHookFunc, getHook GetHookFunc) context.Context {
+	switch v := ctx.Value(correlationsKey).(type) {
+	case correlationsData:
+		v.overrideHook(kind, setHook, getHook)
+		if v.isHookless() {
+			return context.WithValue(ctx, correlationsKey, v.m)
+		}
+		return context.WithValue(ctx, correlationsKey, v)
+	case Map:
+		return contextWithOneHookAndMap(ctx, kind, setHook, getHook, v)
+	default:
+		m := NewEmptyMap()
+		return contextWithOneHookAndMap(ctx, kind, setHook, getHook, m)
+	}
+}
+
+func contextWithOneHookAndMap(ctx context.Context, kind hookKind, setHook SetHookFunc, getHook GetHookFunc, m Map) context.Context {
+	d := correlationsData{m: m}
+	d.overrideHook(kind, setHook, getHook)
+	if d.isHookless() {
+		return ctx
+	}
+	return context.WithValue(ctx, correlationsKey, d)
+}
+
+// ContextWithNoHooks creates a context with all the hooks
+// disabled. Also returns old set and get hooks. This function can be
+// used to temporarily clear the context from hooks and then reinstate
+// them by calling ContextWithSetHook and ContextWithGetHook functions
+// passing the hooks returned by this function.
+//
+// This function should not be used by applications or libraries. It
+// is mostly for interoperation with other observability APIs.
+func ContextWithNoHooks(ctx context.Context) (context.Context, SetHookFunc, GetHookFunc) {
+	switch v := ctx.Value(correlationsKey).(type) {
+	case correlationsData:
+		return context.WithValue(ctx, correlationsKey, v.m), v.setHook, v.getHook
+	default:
+		return ctx, nil, nil
+	}
+}
+
+// ContextWithMap returns a context with the Map entered into it.
+func ContextWithMap(ctx context.Context, m Map) context.Context {
+	switch v := ctx.Value(correlationsKey).(type) {
+	case correlationsData:
+		v.m = m
+		ctx = context.WithValue(ctx, correlationsKey, v)
+		if v.setHook != nil {
+			ctx = v.setHook(ctx)
+		}
+		return ctx
+	default:
+		return context.WithValue(ctx, correlationsKey, m)
+	}
+}
+
+// ContextWithNoCorrelationData returns a context stripped of correlation
+// data.
+func ContextWithNoCorrelationData(ctx context.Context) context.Context {
+	return context.WithValue(ctx, correlationsKey, nil)
+}
+
+// NewContext returns a context with the map from passed context
+// updated with the passed key-value pairs.
+func NewContext(ctx context.Context, keyvalues ...label.KeyValue) context.Context {
+	return ContextWithMap(ctx, MapFromContext(ctx).Apply(MapUpdate{
+		MultiKV: keyvalues,
+	}))
+}
+
+// MapFromContext gets the current Map from a Context.
+func MapFromContext(ctx context.Context) Map {
+	switch v := ctx.Value(correlationsKey).(type) {
+	case correlationsData:
+		if v.getHook != nil {
+			return v.getHook(ctx, v.m)
+		}
+		return v.m
+	case Map:
+		return v
+	default:
+		return NewEmptyMap()
+	}
+}
diff --git a/vendor/go.opentelemetry.io/otel/internal/rawhelpers.go b/vendor/go.opentelemetry.io/otel/internal/rawhelpers.go
new file mode 100644
index 0000000..dae825e
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/internal/rawhelpers.go
@@ -0,0 +1,91 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal
+
+import (
+	"math"
+	"unsafe"
+)
+
+func BoolToRaw(b bool) uint64 {
+	if b {
+		return 1
+	}
+	return 0
+}
+
+func RawToBool(r uint64) bool {
+	return r != 0
+}
+
+func Int64ToRaw(i int64) uint64 {
+	return uint64(i)
+}
+
+func RawToInt64(r uint64) int64 {
+	return int64(r)
+}
+
+func Uint64ToRaw(u uint64) uint64 {
+	return u
+}
+
+func RawToUint64(r uint64) uint64 {
+	return r
+}
+
+func Float64ToRaw(f float64) uint64 {
+	return math.Float64bits(f)
+}
+
+func RawToFloat64(r uint64) float64 {
+	return math.Float64frombits(r)
+}
+
+func Int32ToRaw(i int32) uint64 {
+	return uint64(i)
+}
+
+func RawToInt32(r uint64) int32 {
+	return int32(r)
+}
+
+func Uint32ToRaw(u uint32) uint64 {
+	return uint64(u)
+}
+
+func RawToUint32(r uint64) uint32 {
+	return uint32(r)
+}
+
+func Float32ToRaw(f float32) uint64 {
+	return Uint32ToRaw(math.Float32bits(f))
+}
+
+func RawToFloat32(r uint64) float32 {
+	return math.Float32frombits(RawToUint32(r))
+}
+
+func RawPtrToFloat64Ptr(r *uint64) *float64 {
+	return (*float64)(unsafe.Pointer(r))
+}
+
+func RawPtrToInt64Ptr(r *uint64) *int64 {
+	return (*int64)(unsafe.Pointer(r))
+}
+
+func RawPtrToUint64Ptr(r *uint64) *uint64 {
+	return r
+}
diff --git a/vendor/go.opentelemetry.io/otel/internal/trace/noop/noop.go b/vendor/go.opentelemetry.io/otel/internal/trace/noop/noop.go
new file mode 100644
index 0000000..c09a737
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/internal/trace/noop/noop.go
@@ -0,0 +1,35 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package noop provides noop tracing implementations for tracer and span.
+package noop
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/api/trace"
+)
+
+var (
+	// Tracer is a noop tracer that starts noop spans.
+	Tracer trace.Tracer
+
+	// Span is a noop Span.
+	Span trace.Span
+)
+
+func init() {
+	Tracer = trace.NoopTracerProvider().Tracer("")
+	_, Span = Tracer.Start(context.Background(), "")
+}
diff --git a/vendor/go.opentelemetry.io/otel/label/doc.go b/vendor/go.opentelemetry.io/otel/label/doc.go
new file mode 100644
index 0000000..d631d23
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/label/doc.go
@@ -0,0 +1,16 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package label provides key and value labels.
+package label // import "go.opentelemetry.io/otel/label"
diff --git a/vendor/go.opentelemetry.io/otel/label/encoder.go b/vendor/go.opentelemetry.io/otel/label/encoder.go
new file mode 100644
index 0000000..6be7a3f
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/label/encoder.go
@@ -0,0 +1,150 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package label
+
+import (
+	"bytes"
+	"sync"
+	"sync/atomic"
+)
+
+type (
+	// Encoder is a mechanism for serializing a label set into a
+	// specific string representation that supports caching, to
+	// avoid repeated serialization. An example could be an
+	// exporter encoding the label set into a wire representation.
+	Encoder interface {
+		// Encode returns the serialized encoding of the label
+		// set using its Iterator.  This result may be cached
+		// by a label.Set.
+		Encode(iterator Iterator) string
+
+		// ID returns a value that is unique for each class of
+		// label encoder.  Label encoders allocate these using
+		// `NewEncoderID`.
+		ID() EncoderID
+	}
+
+	// EncoderID is used to identify distinct Encoder
+	// implementations, for caching encoded results.
+	EncoderID struct {
+		value uint64
+	}
+
+	// defaultLabelEncoder uses a sync.Pool of buffers to reduce
+	// the number of allocations used in encoding labels.  This
+	// implementation encodes a comma-separated list of key=value,
+	// with '/'-escaping of '=', ',', and '\'.
+	defaultLabelEncoder struct {
+		// pool is a pool of labelset builders.  The buffers in this
+		// pool grow to a size that most label encodings will not
+		// allocate new memory.
+		pool sync.Pool // *bytes.Buffer
+	}
+)
+
+// escapeChar is used to ensure uniqueness of the label encoding where
+// keys or values contain either '=' or ','.  Since there is no parser
+// needed for this encoding and its only requirement is to be unique,
+// this choice is arbitrary.  Users will see these in some exporters
+// (e.g., stdout), so the backslash ('\') is used as a conventional choice.
+const escapeChar = '\\'
+
+var (
+	_ Encoder = &defaultLabelEncoder{}
+
+	// encoderIDCounter is for generating IDs for other label
+	// encoders.
+	encoderIDCounter uint64
+
+	defaultEncoderOnce     sync.Once
+	defaultEncoderID       = NewEncoderID()
+	defaultEncoderInstance *defaultLabelEncoder
+)
+
+// NewEncoderID returns a unique label encoder ID. It should be
+// called once per each type of label encoder. Preferably in init() or
+// in var definition.
+func NewEncoderID() EncoderID {
+	return EncoderID{value: atomic.AddUint64(&encoderIDCounter, 1)}
+}
+
+// DefaultEncoder returns a label encoder that encodes labels
+// in such a way that each escaped label's key is followed by an equal
+// sign and then by an escaped label's value. All key-value pairs are
+// separated by a comma.
+//
+// Escaping is done by prepending a backslash before either a
+// backslash, equal sign or a comma.
+func DefaultEncoder() Encoder {
+	defaultEncoderOnce.Do(func() {
+		defaultEncoderInstance = &defaultLabelEncoder{
+			pool: sync.Pool{
+				New: func() interface{} {
+					return &bytes.Buffer{}
+				},
+			},
+		}
+	})
+	return defaultEncoderInstance
+}
+
+// Encode is a part of an implementation of the LabelEncoder
+// interface.
+func (d *defaultLabelEncoder) Encode(iter Iterator) string {
+	buf := d.pool.Get().(*bytes.Buffer)
+	defer d.pool.Put(buf)
+	buf.Reset()
+
+	for iter.Next() {
+		i, keyValue := iter.IndexedLabel()
+		if i > 0 {
+			_, _ = buf.WriteRune(',')
+		}
+		copyAndEscape(buf, string(keyValue.Key))
+
+		_, _ = buf.WriteRune('=')
+
+		if keyValue.Value.Type() == STRING {
+			copyAndEscape(buf, keyValue.Value.AsString())
+		} else {
+			_, _ = buf.WriteString(keyValue.Value.Emit())
+		}
+	}
+	return buf.String()
+}
+
+// ID is a part of an implementation of the LabelEncoder interface.
+func (*defaultLabelEncoder) ID() EncoderID {
+	return defaultEncoderID
+}
+
+// copyAndEscape escapes `=`, `,` and its own escape character (`\`),
+// making the default encoding unique.
+func copyAndEscape(buf *bytes.Buffer, val string) {
+	for _, ch := range val {
+		switch ch {
+		case '=', ',', escapeChar:
+			buf.WriteRune(escapeChar)
+		}
+		buf.WriteRune(ch)
+	}
+}
+
+// Valid returns true if this encoder ID was allocated by
+// `NewEncoderID`.  Invalid encoder IDs will not be cached.
+func (id EncoderID) Valid() bool {
+	return id.value != 0
+}
diff --git a/vendor/go.opentelemetry.io/otel/label/iterator.go b/vendor/go.opentelemetry.io/otel/label/iterator.go
new file mode 100644
index 0000000..9e72239
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/label/iterator.go
@@ -0,0 +1,143 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package label
+
+// Iterator allows iterating over the set of labels in order,
+// sorted by key.
+type Iterator struct {
+	storage *Set
+	idx     int
+}
+
+// MergeIterator supports iterating over two sets of labels while
+// eliminating duplicate values from the combined set.  The first
+// iterator value takes precedence.
+type MergeItererator struct {
+	one     oneIterator
+	two     oneIterator
+	current KeyValue
+}
+
+type oneIterator struct {
+	iter  Iterator
+	done  bool
+	label KeyValue
+}
+
+// Next moves the iterator to the next position. Returns false if there
+// are no more labels.
+func (i *Iterator) Next() bool {
+	i.idx++
+	return i.idx < i.Len()
+}
+
+// Label returns current KeyValue. Must be called only after Next returns
+// true.
+func (i *Iterator) Label() KeyValue {
+	kv, _ := i.storage.Get(i.idx)
+	return kv
+}
+
+// Attribute is a synonym for Label().
+func (i *Iterator) Attribute() KeyValue {
+	return i.Label()
+}
+
+// IndexedLabel returns current index and label. Must be called only
+// after Next returns true.
+func (i *Iterator) IndexedLabel() (int, KeyValue) {
+	return i.idx, i.Label()
+}
+
+// Len returns a number of labels in the iterator's `*Set`.
+func (i *Iterator) Len() int {
+	return i.storage.Len()
+}
+
+// ToSlice is a convenience function that creates a slice of labels
+// from the passed iterator. The iterator is set up to start from the
+// beginning before creating the slice.
+func (i *Iterator) ToSlice() []KeyValue {
+	l := i.Len()
+	if l == 0 {
+		return nil
+	}
+	i.idx = -1
+	slice := make([]KeyValue, 0, l)
+	for i.Next() {
+		slice = append(slice, i.Label())
+	}
+	return slice
+}
+
+// NewMergeIterator returns a MergeIterator for merging two label sets
+// Duplicates are resolved by taking the value from the first set.
+func NewMergeIterator(s1, s2 *Set) MergeItererator {
+	mi := MergeItererator{
+		one: makeOne(s1.Iter()),
+		two: makeOne(s2.Iter()),
+	}
+	return mi
+}
+
+func makeOne(iter Iterator) oneIterator {
+	oi := oneIterator{
+		iter: iter,
+	}
+	oi.advance()
+	return oi
+}
+
+func (oi *oneIterator) advance() {
+	if oi.done = !oi.iter.Next(); !oi.done {
+		oi.label = oi.iter.Label()
+	}
+}
+
+// Next returns true if there is another label available.
+func (m *MergeItererator) Next() bool {
+	if m.one.done && m.two.done {
+		return false
+	}
+	if m.one.done {
+		m.current = m.two.label
+		m.two.advance()
+		return true
+	}
+	if m.two.done {
+		m.current = m.one.label
+		m.one.advance()
+		return true
+	}
+	if m.one.label.Key == m.two.label.Key {
+		m.current = m.one.label // first iterator label value wins
+		m.one.advance()
+		m.two.advance()
+		return true
+	}
+	if m.one.label.Key < m.two.label.Key {
+		m.current = m.one.label
+		m.one.advance()
+		return true
+	}
+	m.current = m.two.label
+	m.two.advance()
+	return true
+}
+
+// Label returns the current value after Next() returns true.
+func (m *MergeItererator) Label() KeyValue {
+	return m.current
+}
diff --git a/vendor/go.opentelemetry.io/otel/label/key.go b/vendor/go.opentelemetry.io/otel/label/key.go
new file mode 100644
index 0000000..7d72378
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/label/key.go
@@ -0,0 +1,169 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package label
+
+// Key represents the key part in key-value pairs. It's a string. The
+// allowed character set in the key depends on the use of the key.
+type Key string
+
+// Bool creates a KeyValue instance with a BOOL Value.
+//
+// If creating both key and a bool value at the same time, then
+// instead of calling Key(name).Bool(value) consider using a
+// convenience function provided by the api/key package -
+// key.Bool(name, value).
+func (k Key) Bool(v bool) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: BoolValue(v),
+	}
+}
+
+// Int64 creates a KeyValue instance with an INT64 Value.
+//
+// If creating both key and an int64 value at the same time, then
+// instead of calling Key(name).Int64(value) consider using a
+// convenience function provided by the api/key package -
+// key.Int64(name, value).
+func (k Key) Int64(v int64) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: Int64Value(v),
+	}
+}
+
+// Uint64 creates a KeyValue instance with a UINT64 Value.
+//
+// If creating both key and a uint64 value at the same time, then
+// instead of calling Key(name).Uint64(value) consider using a
+// convenience function provided by the api/key package -
+// key.Uint64(name, value).
+func (k Key) Uint64(v uint64) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: Uint64Value(v),
+	}
+}
+
+// Float64 creates a KeyValue instance with a FLOAT64 Value.
+//
+// If creating both key and a float64 value at the same time, then
+// instead of calling Key(name).Float64(value) consider using a
+// convenience function provided by the api/key package -
+// key.Float64(name, value).
+func (k Key) Float64(v float64) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: Float64Value(v),
+	}
+}
+
+// Int32 creates a KeyValue instance with an INT32 Value.
+//
+// If creating both key and an int32 value at the same time, then
+// instead of calling Key(name).Int32(value) consider using a
+// convenience function provided by the api/key package -
+// key.Int32(name, value).
+func (k Key) Int32(v int32) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: Int32Value(v),
+	}
+}
+
+// Uint32 creates a KeyValue instance with a UINT32 Value.
+//
+// If creating both key and a uint32 value at the same time, then
+// instead of calling Key(name).Uint32(value) consider using a
+// convenience function provided by the api/key package -
+// key.Uint32(name, value).
+func (k Key) Uint32(v uint32) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: Uint32Value(v),
+	}
+}
+
+// Float32 creates a KeyValue instance with a FLOAT32 Value.
+//
+// If creating both key and a float32 value at the same time, then
+// instead of calling Key(name).Float32(value) consider using a
+// convenience function provided by the api/key package -
+// key.Float32(name, value).
+func (k Key) Float32(v float32) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: Float32Value(v),
+	}
+}
+
+// String creates a KeyValue instance with a STRING Value.
+//
+// If creating both key and a string value at the same time, then
+// instead of calling Key(name).String(value) consider using a
+// convenience function provided by the api/key package -
+// key.String(name, value).
+func (k Key) String(v string) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: StringValue(v),
+	}
+}
+
+// Int creates a KeyValue instance with either an INT32 or an INT64
+// Value, depending on whether the int type is 32 or 64 bits wide.
+//
+// If creating both key and an int value at the same time, then
+// instead of calling Key(name).Int(value) consider using a
+// convenience function provided by the api/key package -
+// key.Int(name, value).
+func (k Key) Int(v int) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: IntValue(v),
+	}
+}
+
+// Uint creates a KeyValue instance with either a UINT32 or a UINT64
+// Value, depending on whether the uint type is 32 or 64 bits wide.
+//
+// If creating both key and a uint value at the same time, then
+// instead of calling Key(name).Uint(value) consider using a
+// convenience function provided by the api/key package -
+// key.Uint(name, value).
+func (k Key) Uint(v uint) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: UintValue(v),
+	}
+}
+
+// Defined returns true for non-empty keys.
+func (k Key) Defined() bool {
+	return len(k) != 0
+}
+
+// Array creates a KeyValue instance with a ARRAY Value.
+//
+// If creating both key and a array value at the same time, then
+// instead of calling Key(name).String(value) consider using a
+// convenience function provided by the api/key package -
+// key.Array(name, value).
+func (k Key) Array(v interface{}) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: ArrayValue(v),
+	}
+}
diff --git a/vendor/go.opentelemetry.io/otel/label/kv.go b/vendor/go.opentelemetry.io/otel/label/kv.go
new file mode 100644
index 0000000..3e2764f
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/label/kv.go
@@ -0,0 +1,144 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package label
+
+import (
+	"encoding/json"
+	"fmt"
+	"reflect"
+)
+
+// KeyValue holds a key and value pair.
+type KeyValue struct {
+	Key   Key
+	Value Value
+}
+
+// Bool creates a new key-value pair with a passed name and a bool
+// value.
+func Bool(k string, v bool) KeyValue {
+	return Key(k).Bool(v)
+}
+
+// Int64 creates a new key-value pair with a passed name and an int64
+// value.
+func Int64(k string, v int64) KeyValue {
+	return Key(k).Int64(v)
+}
+
+// Uint64 creates a new key-value pair with a passed name and a uint64
+// value.
+func Uint64(k string, v uint64) KeyValue {
+	return Key(k).Uint64(v)
+}
+
+// Float64 creates a new key-value pair with a passed name and a float64
+// value.
+func Float64(k string, v float64) KeyValue {
+	return Key(k).Float64(v)
+}
+
+// Int32 creates a new key-value pair with a passed name and an int32
+// value.
+func Int32(k string, v int32) KeyValue {
+	return Key(k).Int32(v)
+}
+
+// Uint32 creates a new key-value pair with a passed name and a uint32
+// value.
+func Uint32(k string, v uint32) KeyValue {
+	return Key(k).Uint32(v)
+}
+
+// Float32 creates a new key-value pair with a passed name and a float32
+// value.
+func Float32(k string, v float32) KeyValue {
+	return Key(k).Float32(v)
+}
+
+// String creates a new key-value pair with a passed name and a string
+// value.
+func String(k, v string) KeyValue {
+	return Key(k).String(v)
+}
+
+// Stringer creates a new key-value pair with a passed name and a string
+// value generated by the passed Stringer interface.
+func Stringer(k string, v fmt.Stringer) KeyValue {
+	return Key(k).String(v.String())
+}
+
+// Int creates a new key-value pair instance with a passed name and
+// either an int32 or an int64 value, depending on whether the int
+// type is 32 or 64 bits wide.
+func Int(k string, v int) KeyValue {
+	return Key(k).Int(v)
+}
+
+// Uint creates a new key-value pair instance with a passed name and
+// either an uint32 or an uint64 value, depending on whether the uint
+// type is 32 or 64 bits wide.
+func Uint(k string, v uint) KeyValue {
+	return Key(k).Uint(v)
+}
+
+// Array creates a new key-value pair with a passed name and a array.
+// Only arrays of primitive type are supported.
+func Array(k string, v interface{}) KeyValue {
+	return Key(k).Array(v)
+}
+
+// Any creates a new key-value pair instance with a passed name and
+// automatic type inference. This is slower, and not type-safe.
+func Any(k string, value interface{}) KeyValue {
+	if value == nil {
+		return String(k, "<nil>")
+	}
+
+	if stringer, ok := value.(fmt.Stringer); ok {
+		return String(k, stringer.String())
+	}
+
+	rv := reflect.ValueOf(value)
+
+	switch rv.Kind() {
+	case reflect.Array, reflect.Slice:
+		return Array(k, value)
+	case reflect.Bool:
+		return Bool(k, rv.Bool())
+	case reflect.Int, reflect.Int8, reflect.Int16:
+		return Int(k, int(rv.Int()))
+	case reflect.Int32:
+		return Int32(k, int32(rv.Int()))
+	case reflect.Int64:
+		return Int64(k, int64(rv.Int()))
+	case reflect.Uint, reflect.Uint8, reflect.Uint16:
+		return Uint(k, uint(rv.Uint()))
+	case reflect.Uint32:
+		return Uint32(k, uint32(rv.Uint()))
+	case reflect.Uint64, reflect.Uintptr:
+		return Uint64(k, rv.Uint())
+	case reflect.Float32:
+		return Float32(k, float32(rv.Float()))
+	case reflect.Float64:
+		return Float64(k, rv.Float())
+	case reflect.String:
+		return String(k, rv.String())
+	}
+	if b, err := json.Marshal(value); value != nil && err == nil {
+		return String(k, string(b))
+	}
+	return String(k, fmt.Sprint(value))
+}
diff --git a/vendor/go.opentelemetry.io/otel/label/set.go b/vendor/go.opentelemetry.io/otel/label/set.go
new file mode 100644
index 0000000..3bd5263
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/label/set.go
@@ -0,0 +1,468 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package label
+
+import (
+	"encoding/json"
+	"reflect"
+	"sort"
+	"sync"
+)
+
+type (
+	// Set is the representation for a distinct label set.  It
+	// manages an immutable set of labels, with an internal cache
+	// for storing label encodings.
+	//
+	// This type supports the `Equivalent` method of comparison
+	// using values of type `Distinct`.
+	//
+	// This type is used to implement:
+	// 1. Metric labels
+	// 2. Resource sets
+	// 3. Correlation map (TODO)
+	Set struct {
+		equivalent Distinct
+
+		lock     sync.Mutex
+		encoders [maxConcurrentEncoders]EncoderID
+		encoded  [maxConcurrentEncoders]string
+	}
+
+	// Distinct wraps a variable-size array of `KeyValue`,
+	// constructed with keys in sorted order.  This can be used as
+	// a map key or for equality checking between Sets.
+	Distinct struct {
+		iface interface{}
+	}
+
+	// Filter supports removing certain labels from label sets.
+	// When the filter returns true, the label will be kept in
+	// the filtered label set.  When the filter returns false, the
+	// label is excluded from the filtered label set, and the
+	// label instead appears in the `removed` list of excluded labels.
+	Filter func(KeyValue) bool
+
+	// Sortable implements `sort.Interface`, used for sorting
+	// `KeyValue`.  This is an exported type to support a
+	// memory optimization.  A pointer to one of these is needed
+	// for the call to `sort.Stable()`, which the caller may
+	// provide in order to avoid an allocation.  See
+	// `NewSetWithSortable()`.
+	Sortable []KeyValue
+)
+
+var (
+	// keyValueType is used in `computeDistinctReflect`.
+	keyValueType = reflect.TypeOf(KeyValue{})
+
+	// emptySet is returned for empty label sets.
+	emptySet = &Set{
+		equivalent: Distinct{
+			iface: [0]KeyValue{},
+		},
+	}
+)
+
+const maxConcurrentEncoders = 3
+
+func EmptySet() *Set {
+	return emptySet
+}
+
+// reflect abbreviates `reflect.ValueOf`.
+func (d Distinct) reflect() reflect.Value {
+	return reflect.ValueOf(d.iface)
+}
+
+// Valid returns true if this value refers to a valid `*Set`.
+func (d Distinct) Valid() bool {
+	return d.iface != nil
+}
+
+// Len returns the number of labels in this set.
+func (l *Set) Len() int {
+	if l == nil || !l.equivalent.Valid() {
+		return 0
+	}
+	return l.equivalent.reflect().Len()
+}
+
+// Get returns the KeyValue at ordered position `idx` in this set.
+func (l *Set) Get(idx int) (KeyValue, bool) {
+	if l == nil {
+		return KeyValue{}, false
+	}
+	value := l.equivalent.reflect()
+
+	if idx >= 0 && idx < value.Len() {
+		// Note: The Go compiler successfully avoids an allocation for
+		// the interface{} conversion here:
+		return value.Index(idx).Interface().(KeyValue), true
+	}
+
+	return KeyValue{}, false
+}
+
+// Value returns the value of a specified key in this set.
+func (l *Set) Value(k Key) (Value, bool) {
+	if l == nil {
+		return Value{}, false
+	}
+	rValue := l.equivalent.reflect()
+	vlen := rValue.Len()
+
+	idx := sort.Search(vlen, func(idx int) bool {
+		return rValue.Index(idx).Interface().(KeyValue).Key >= k
+	})
+	if idx >= vlen {
+		return Value{}, false
+	}
+	keyValue := rValue.Index(idx).Interface().(KeyValue)
+	if k == keyValue.Key {
+		return keyValue.Value, true
+	}
+	return Value{}, false
+}
+
+// HasValue tests whether a key is defined in this set.
+func (l *Set) HasValue(k Key) bool {
+	if l == nil {
+		return false
+	}
+	_, ok := l.Value(k)
+	return ok
+}
+
+// Iter returns an iterator for visiting the labels in this set.
+func (l *Set) Iter() Iterator {
+	return Iterator{
+		storage: l,
+		idx:     -1,
+	}
+}
+
+// ToSlice returns the set of labels belonging to this set, sorted,
+// where keys appear no more than once.
+func (l *Set) ToSlice() []KeyValue {
+	iter := l.Iter()
+	return iter.ToSlice()
+}
+
+// Equivalent returns a value that may be used as a map key.  The
+// Distinct type guarantees that the result will equal the equivalent
+// Distinct value of any label set with the same elements as this,
+// where sets are made unique by choosing the last value in the input
+// for any given key.
+func (l *Set) Equivalent() Distinct {
+	if l == nil || !l.equivalent.Valid() {
+		return emptySet.equivalent
+	}
+	return l.equivalent
+}
+
+// Equals returns true if the argument set is equivalent to this set.
+func (l *Set) Equals(o *Set) bool {
+	return l.Equivalent() == o.Equivalent()
+}
+
+// Encoded returns the encoded form of this set, according to
+// `encoder`.  The result will be cached in this `*Set`.
+func (l *Set) Encoded(encoder Encoder) string {
+	if l == nil || encoder == nil {
+		return ""
+	}
+
+	id := encoder.ID()
+	if !id.Valid() {
+		// Invalid IDs are not cached.
+		return encoder.Encode(l.Iter())
+	}
+
+	var lookup *string
+	l.lock.Lock()
+	for idx := 0; idx < maxConcurrentEncoders; idx++ {
+		if l.encoders[idx] == id {
+			lookup = &l.encoded[idx]
+			break
+		}
+	}
+	l.lock.Unlock()
+
+	if lookup != nil {
+		return *lookup
+	}
+
+	r := encoder.Encode(l.Iter())
+
+	l.lock.Lock()
+	defer l.lock.Unlock()
+
+	for idx := 0; idx < maxConcurrentEncoders; idx++ {
+		if l.encoders[idx] == id {
+			return l.encoded[idx]
+		}
+		if !l.encoders[idx].Valid() {
+			l.encoders[idx] = id
+			l.encoded[idx] = r
+			return r
+		}
+	}
+
+	// TODO: This is a performance cliff.  Find a way for this to
+	// generate a warning.
+	return r
+}
+
+func empty() Set {
+	return Set{
+		equivalent: emptySet.equivalent,
+	}
+}
+
+// NewSet returns a new `Set`.  See the documentation for
+// `NewSetWithSortableFiltered` for more details.
+//
+// Except for empty sets, this method adds an additional allocation
+// compared with calls that include a `*Sortable`.
+func NewSet(kvs ...KeyValue) Set {
+	// Check for empty set.
+	if len(kvs) == 0 {
+		return empty()
+	}
+	s, _ := NewSetWithSortableFiltered(kvs, new(Sortable), nil)
+	return s //nolint
+}
+
+// NewSetWithSortable returns a new `Set`.  See the documentation for
+// `NewSetWithSortableFiltered` for more details.
+//
+// This call includes a `*Sortable` option as a memory optimization.
+func NewSetWithSortable(kvs []KeyValue, tmp *Sortable) Set {
+	// Check for empty set.
+	if len(kvs) == 0 {
+		return empty()
+	}
+	s, _ := NewSetWithSortableFiltered(kvs, tmp, nil)
+	return s //nolint
+}
+
+// NewSetWithFiltered returns a new `Set`.  See the documentation for
+// `NewSetWithSortableFiltered` for more details.
+//
+// This call includes a `Filter` to include/exclude label keys from
+// the return value.  Excluded keys are returned as a slice of label
+// values.
+func NewSetWithFiltered(kvs []KeyValue, filter Filter) (Set, []KeyValue) {
+	// Check for empty set.
+	if len(kvs) == 0 {
+		return empty(), nil
+	}
+	return NewSetWithSortableFiltered(kvs, new(Sortable), filter)
+}
+
+// NewSetWithSortableFiltered returns a new `Set`.
+//
+// Duplicate keys are eliminated by taking the last value.  This
+// re-orders the input slice so that unique last-values are contiguous
+// at the end of the slice.
+//
+// This ensures the following:
+//
+// - Last-value-wins semantics
+// - Caller sees the reordering, but doesn't lose values
+// - Repeated call preserve last-value wins.
+//
+// Note that methods are defined on `*Set`, although this returns `Set`.
+// Callers can avoid memory allocations by:
+//
+// - allocating a `Sortable` for use as a temporary in this method
+// - allocating a `Set` for storing the return value of this
+//   constructor.
+//
+// The result maintains a cache of encoded labels, by label.EncoderID.
+// This value should not be copied after its first use.
+//
+// The second `[]KeyValue` return value is a list of labels that were
+// excluded by the Filter (if non-nil).
+func NewSetWithSortableFiltered(kvs []KeyValue, tmp *Sortable, filter Filter) (Set, []KeyValue) {
+	// Check for empty set.
+	if len(kvs) == 0 {
+		return empty(), nil
+	}
+
+	*tmp = kvs
+
+	// Stable sort so the following de-duplication can implement
+	// last-value-wins semantics.
+	sort.Stable(tmp)
+
+	*tmp = nil
+
+	position := len(kvs) - 1
+	offset := position - 1
+
+	// The requirements stated above require that the stable
+	// result be placed in the end of the input slice, while
+	// overwritten values are swapped to the beginning.
+	//
+	// De-duplicate with last-value-wins semantics.  Preserve
+	// duplicate values at the beginning of the input slice.
+	for ; offset >= 0; offset-- {
+		if kvs[offset].Key == kvs[position].Key {
+			continue
+		}
+		position--
+		kvs[offset], kvs[position] = kvs[position], kvs[offset]
+	}
+	if filter != nil {
+		return filterSet(kvs[position:], filter)
+	}
+	return Set{
+		equivalent: computeDistinct(kvs[position:]),
+	}, nil
+}
+
+// filterSet reorders `kvs` so that included keys are contiguous at
+// the end of the slice, while excluded keys precede the included keys.
+func filterSet(kvs []KeyValue, filter Filter) (Set, []KeyValue) {
+	var excluded []KeyValue
+
+	// Move labels that do not match the filter so
+	// they're adjacent before calling computeDistinct().
+	distinctPosition := len(kvs)
+
+	// Swap indistinct keys forward and distinct keys toward the
+	// end of the slice.
+	offset := len(kvs) - 1
+	for ; offset >= 0; offset-- {
+		if filter(kvs[offset]) {
+			distinctPosition--
+			kvs[offset], kvs[distinctPosition] = kvs[distinctPosition], kvs[offset]
+			continue
+		}
+	}
+	excluded = kvs[:distinctPosition]
+
+	return Set{
+		equivalent: computeDistinct(kvs[distinctPosition:]),
+	}, excluded
+}
+
+// Filter returns a filtered copy of this `Set`.  See the
+// documentation for `NewSetWithSortableFiltered` for more details.
+func (l *Set) Filter(re Filter) (Set, []KeyValue) {
+	if re == nil {
+		return Set{
+			equivalent: l.equivalent,
+		}, nil
+	}
+
+	// Note: This could be refactored to avoid the temporary slice
+	// allocation, if it proves to be expensive.
+	return filterSet(l.ToSlice(), re)
+}
+
+// computeDistinct returns a `Distinct` using either the fixed- or
+// reflect-oriented code path, depending on the size of the input.
+// The input slice is assumed to already be sorted and de-duplicated.
+func computeDistinct(kvs []KeyValue) Distinct {
+	iface := computeDistinctFixed(kvs)
+	if iface == nil {
+		iface = computeDistinctReflect(kvs)
+	}
+	return Distinct{
+		iface: iface,
+	}
+}
+
+// computeDistinctFixed computes a `Distinct` for small slices.  It
+// returns nil if the input is too large for this code path.
+func computeDistinctFixed(kvs []KeyValue) interface{} {
+	switch len(kvs) {
+	case 1:
+		ptr := new([1]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 2:
+		ptr := new([2]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 3:
+		ptr := new([3]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 4:
+		ptr := new([4]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 5:
+		ptr := new([5]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 6:
+		ptr := new([6]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 7:
+		ptr := new([7]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 8:
+		ptr := new([8]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 9:
+		ptr := new([9]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	case 10:
+		ptr := new([10]KeyValue)
+		copy((*ptr)[:], kvs)
+		return *ptr
+	default:
+		return nil
+	}
+}
+
+// computeDistinctReflect computes a `Distinct` using reflection,
+// works for any size input.
+func computeDistinctReflect(kvs []KeyValue) interface{} {
+	at := reflect.New(reflect.ArrayOf(len(kvs), keyValueType)).Elem()
+	for i, keyValue := range kvs {
+		*(at.Index(i).Addr().Interface().(*KeyValue)) = keyValue
+	}
+	return at.Interface()
+}
+
+// MarshalJSON returns the JSON encoding of the `*Set`.
+func (l *Set) MarshalJSON() ([]byte, error) {
+	return json.Marshal(l.equivalent.iface)
+}
+
+// Len implements `sort.Interface`.
+func (l *Sortable) Len() int {
+	return len(*l)
+}
+
+// Swap implements `sort.Interface`.
+func (l *Sortable) Swap(i, j int) {
+	(*l)[i], (*l)[j] = (*l)[j], (*l)[i]
+}
+
+// Less implements `sort.Interface`.
+func (l *Sortable) Less(i, j int) bool {
+	return (*l)[i].Key < (*l)[j].Key
+}
diff --git a/vendor/go.opentelemetry.io/otel/label/type_string.go b/vendor/go.opentelemetry.io/otel/label/type_string.go
new file mode 100644
index 0000000..62afeb6
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/label/type_string.go
@@ -0,0 +1,32 @@
+// Code generated by "stringer -type=Type"; DO NOT EDIT.
+
+package label
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[INVALID-0]
+	_ = x[BOOL-1]
+	_ = x[INT32-2]
+	_ = x[INT64-3]
+	_ = x[UINT32-4]
+	_ = x[UINT64-5]
+	_ = x[FLOAT32-6]
+	_ = x[FLOAT64-7]
+	_ = x[STRING-8]
+	_ = x[ARRAY-9]
+}
+
+const _Type_name = "INVALIDBOOLINT32INT64UINT32UINT64FLOAT32FLOAT64STRINGARRAY"
+
+var _Type_index = [...]uint8{0, 7, 11, 16, 21, 27, 33, 40, 47, 53, 58}
+
+func (i Type) String() string {
+	if i < 0 || i >= Type(len(_Type_index)-1) {
+		return "Type(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _Type_name[_Type_index[i]:_Type_index[i+1]]
+}
diff --git a/vendor/go.opentelemetry.io/otel/label/value.go b/vendor/go.opentelemetry.io/otel/label/value.go
new file mode 100644
index 0000000..679009b
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/label/value.go
@@ -0,0 +1,288 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package label
+
+import (
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"strconv"
+	"unsafe"
+
+	"go.opentelemetry.io/otel/internal"
+)
+
+//go:generate stringer -type=Type
+
+// Type describes the type of the data Value holds.
+type Type int
+
+// Value represents the value part in key-value pairs.
+type Value struct {
+	vtype    Type
+	numeric  uint64
+	stringly string
+	// TODO Lazy value type?
+
+	array interface{}
+}
+
+const (
+	INVALID Type = iota // No value.
+	BOOL                // Boolean value, use AsBool() to get it.
+	INT32               // 32 bit signed integral value, use AsInt32() to get it.
+	INT64               // 64 bit signed integral value, use AsInt64() to get it.
+	UINT32              // 32 bit unsigned integral value, use AsUint32() to get it.
+	UINT64              // 64 bit unsigned integral value, use AsUint64() to get it.
+	FLOAT32             // 32 bit floating point value, use AsFloat32() to get it.
+	FLOAT64             // 64 bit floating point value, use AsFloat64() to get it.
+	STRING              // String value, use AsString() to get it.
+	ARRAY               // Array value of arbitrary type, use AsArray() to get it.
+)
+
+// BoolValue creates a BOOL Value.
+func BoolValue(v bool) Value {
+	return Value{
+		vtype:   BOOL,
+		numeric: internal.BoolToRaw(v),
+	}
+}
+
+// Int64Value creates an INT64 Value.
+func Int64Value(v int64) Value {
+	return Value{
+		vtype:   INT64,
+		numeric: internal.Int64ToRaw(v),
+	}
+}
+
+// Uint64Value creates a UINT64 Value.
+func Uint64Value(v uint64) Value {
+	return Value{
+		vtype:   UINT64,
+		numeric: internal.Uint64ToRaw(v),
+	}
+}
+
+// Float64Value creates a FLOAT64 Value.
+func Float64Value(v float64) Value {
+	return Value{
+		vtype:   FLOAT64,
+		numeric: internal.Float64ToRaw(v),
+	}
+}
+
+// Int32Value creates an INT32 Value.
+func Int32Value(v int32) Value {
+	return Value{
+		vtype:   INT32,
+		numeric: internal.Int32ToRaw(v),
+	}
+}
+
+// Uint32Value creates a UINT32 Value.
+func Uint32Value(v uint32) Value {
+	return Value{
+		vtype:   UINT32,
+		numeric: internal.Uint32ToRaw(v),
+	}
+}
+
+// Float32Value creates a FLOAT32 Value.
+func Float32Value(v float32) Value {
+	return Value{
+		vtype:   FLOAT32,
+		numeric: internal.Float32ToRaw(v),
+	}
+}
+
+// StringValue creates a STRING Value.
+func StringValue(v string) Value {
+	return Value{
+		vtype:    STRING,
+		stringly: v,
+	}
+}
+
+// IntValue creates either an INT32 or an INT64 Value, depending on whether
+// the int type is 32 or 64 bits wide.
+func IntValue(v int) Value {
+	if unsafe.Sizeof(v) == 4 {
+		return Int32Value(int32(v))
+	}
+	return Int64Value(int64(v))
+}
+
+// UintValue creates either a UINT32 or a UINT64 Value, depending on whether
+// the uint type is 32 or 64 bits wide.
+func UintValue(v uint) Value {
+	if unsafe.Sizeof(v) == 4 {
+		return Uint32Value(uint32(v))
+	}
+	return Uint64Value(uint64(v))
+}
+
+// ArrayValue creates an ARRAY value from an array or slice.
+// Only arrays or slices of bool, int, int32, int64, uint, uint32, uint64,
+// float, float32, float64, or string types are allowed. Specifically, arrays
+// and slices can not contain other arrays, slices, structs, or non-standard
+// types. If the passed value is not an array or slice of these types an
+// INVALID value is returned.
+func ArrayValue(v interface{}) Value {
+	switch reflect.TypeOf(v).Kind() {
+	case reflect.Array, reflect.Slice:
+		// get array type regardless of dimensions
+		typ := reflect.TypeOf(v).Elem()
+		kind := typ.Kind()
+		switch kind {
+		case reflect.Bool, reflect.Int, reflect.Int32, reflect.Int64,
+			reflect.Float32, reflect.Float64, reflect.String,
+			reflect.Uint, reflect.Uint32, reflect.Uint64:
+			val := reflect.ValueOf(v)
+			length := val.Len()
+			frozen := reflect.Indirect(reflect.New(reflect.ArrayOf(length, typ)))
+			reflect.Copy(frozen, val)
+			return Value{
+				vtype: ARRAY,
+				array: frozen.Interface(),
+			}
+		default:
+			return Value{vtype: INVALID}
+		}
+	}
+	return Value{vtype: INVALID}
+}
+
+// Type returns a type of the Value.
+func (v Value) Type() Type {
+	return v.vtype
+}
+
+// AsBool returns the bool value. Make sure that the Value's type is
+// BOOL.
+func (v Value) AsBool() bool {
+	return internal.RawToBool(v.numeric)
+}
+
+// AsInt32 returns the int32 value. Make sure that the Value's type is
+// INT32.
+func (v Value) AsInt32() int32 {
+	return internal.RawToInt32(v.numeric)
+}
+
+// AsInt64 returns the int64 value. Make sure that the Value's type is
+// INT64.
+func (v Value) AsInt64() int64 {
+	return internal.RawToInt64(v.numeric)
+}
+
+// AsUint32 returns the uint32 value. Make sure that the Value's type
+// is UINT32.
+func (v Value) AsUint32() uint32 {
+	return internal.RawToUint32(v.numeric)
+}
+
+// AsUint64 returns the uint64 value. Make sure that the Value's type is
+// UINT64.
+func (v Value) AsUint64() uint64 {
+	return internal.RawToUint64(v.numeric)
+}
+
+// AsFloat32 returns the float32 value. Make sure that the Value's
+// type is FLOAT32.
+func (v Value) AsFloat32() float32 {
+	return internal.RawToFloat32(v.numeric)
+}
+
+// AsFloat64 returns the float64 value. Make sure that the Value's
+// type is FLOAT64.
+func (v Value) AsFloat64() float64 {
+	return internal.RawToFloat64(v.numeric)
+}
+
+// AsString returns the string value. Make sure that the Value's type
+// is STRING.
+func (v Value) AsString() string {
+	return v.stringly
+}
+
+// AsArray returns the array Value as an interface{}.
+func (v Value) AsArray() interface{} {
+	return v.array
+}
+
+type unknownValueType struct{}
+
+// AsInterface returns Value's data as interface{}.
+func (v Value) AsInterface() interface{} {
+	switch v.Type() {
+	case ARRAY:
+		return v.AsArray()
+	case BOOL:
+		return v.AsBool()
+	case INT32:
+		return v.AsInt32()
+	case INT64:
+		return v.AsInt64()
+	case UINT32:
+		return v.AsUint32()
+	case UINT64:
+		return v.AsUint64()
+	case FLOAT32:
+		return v.AsFloat32()
+	case FLOAT64:
+		return v.AsFloat64()
+	case STRING:
+		return v.stringly
+	}
+	return unknownValueType{}
+}
+
+// Emit returns a string representation of Value's data.
+func (v Value) Emit() string {
+	switch v.Type() {
+	case ARRAY:
+		return fmt.Sprint(v.array)
+	case BOOL:
+		return strconv.FormatBool(v.AsBool())
+	case INT32:
+		return strconv.FormatInt(int64(v.AsInt32()), 10)
+	case INT64:
+		return strconv.FormatInt(v.AsInt64(), 10)
+	case UINT32:
+		return strconv.FormatUint(uint64(v.AsUint32()), 10)
+	case UINT64:
+		return strconv.FormatUint(v.AsUint64(), 10)
+	case FLOAT32:
+		return fmt.Sprint(v.AsFloat32())
+	case FLOAT64:
+		return fmt.Sprint(v.AsFloat64())
+	case STRING:
+		return v.stringly
+	default:
+		return "unknown"
+	}
+}
+
+// MarshalJSON returns the JSON encoding of the Value.
+func (v Value) MarshalJSON() ([]byte, error) {
+	var jsonVal struct {
+		Type  string
+		Value interface{}
+	}
+	jsonVal.Type = v.Type().String()
+	jsonVal.Value = v.AsInterface()
+	return json.Marshal(jsonVal)
+}
diff --git a/vendor/go.opentelemetry.io/otel/otel.go b/vendor/go.opentelemetry.io/otel/otel.go
new file mode 100644
index 0000000..aaabac2
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/otel.go
@@ -0,0 +1,31 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package otel
+
+import (
+	"go.opentelemetry.io/otel/api/metric"
+	"go.opentelemetry.io/otel/api/trace"
+)
+
+type Tracer = trace.Tracer
+
+type Meter = metric.Meter
+
+// ErrorHandler handles irremediable events.
+type ErrorHandler interface {
+	// Handle handles any error deemed irremediable by an OpenTelemetry
+	// component.
+	Handle(error)
+}
diff --git a/vendor/go.opentelemetry.io/otel/pre_release.sh b/vendor/go.opentelemetry.io/otel/pre_release.sh
new file mode 100644
index 0000000..e09924b
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/pre_release.sh
@@ -0,0 +1,95 @@
+#!/bin/bash
+
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -e
+
+help()
+{
+   printf "\n"
+   printf "Usage: $0 -t tag\n"
+   printf "\t-t Unreleased tag. Update all go.mod with this tag.\n"
+   exit 1 # Exit script after printing help
+}
+
+while getopts "t:" opt
+do
+   case "$opt" in
+      t ) TAG="$OPTARG" ;;
+      ? ) help ;; # Print help
+   esac
+done
+
+# Print help in case parameters are empty
+if [ -z "$TAG" ]
+then
+   printf "Tag is missing\n";
+   help
+fi
+
+# Validate semver
+SEMVER_REGEX="^v(0|[1-9][0-9]*)\\.(0|[1-9][0-9]*)\\.(0|[1-9][0-9]*)(\\-[0-9A-Za-z-]+(\\.[0-9A-Za-z-]+)*)?(\\+[0-9A-Za-z-]+(\\.[0-9A-Za-z-]+)*)?$"
+if [[ "${TAG}" =~ ${SEMVER_REGEX} ]]; then
+	printf "${TAG} is valid semver tag.\n"
+else
+	printf "${TAG} is not a valid semver tag.\n"
+	exit -1
+fi
+
+TAG_FOUND=`git tag --list ${TAG}`
+if [[ ${TAG_FOUND} = ${TAG} ]] ; then
+        printf "Tag ${TAG} already exists\n"
+        exit -1
+fi
+
+# Get version for sdk/opentelemetry.go
+OTEL_VERSION=$(echo "${TAG}" | grep -o '^v[0-9]\+\.[0-9]\+\.[0-9]\+')
+# Strip leading v
+OTEL_VERSION="${OTEL_VERSION#v}"
+
+cd $(dirname $0)
+
+if ! git diff --quiet; then \
+	printf "Working tree is not clean, can't proceed with the release process\n"
+	git status
+	git diff
+	exit 1
+fi
+
+# Update sdk/opentelemetry.go
+cp ./sdk/opentelemetry.go ./sdk/opentelemetry.go.bak
+sed "s/\(return \"\)[0-9]*\.[0-9]*\.[0-9]*\"/\1${OTEL_VERSION}\"/" ./sdk/opentelemetry.go.bak >./sdk/opentelemetry.go
+rm -f ./sdk/opentelemetry.go.bak
+
+# Update go.mod
+git checkout -b pre_release_${TAG} master
+PACKAGE_DIRS=$(find . -mindepth 2 -type f -name 'go.mod' -exec dirname {} \; | egrep -v 'tools' | sed 's/^\.\///' | sort)
+
+for dir in $PACKAGE_DIRS; do
+	cp "${dir}/go.mod" "${dir}/go.mod.bak"
+	sed "s/opentelemetry.io\/otel\([^ ]*\) v[0-9]*\.[0-9]*\.[0-9]/opentelemetry.io\/otel\1 ${TAG}/" "${dir}/go.mod.bak" >"${dir}/go.mod"
+	rm -f "${dir}/go.mod.bak"
+done
+
+# Run lint to update go.sum
+make lint
+
+# Add changes and commit.
+git add .
+make ci
+git commit -m "Prepare for releasing $TAG"
+
+printf "Now run following to verify the changes.\ngit diff master\n"
+printf "\nThen push the changes to upstream\n"
diff --git a/vendor/go.opentelemetry.io/otel/propagation.go b/vendor/go.opentelemetry.io/otel/propagation.go
new file mode 100644
index 0000000..8e3bd8d
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/propagation.go
@@ -0,0 +1,78 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package otel
+
+import "context"
+
+// TextMapCarrier is the storage medium used by a TextMapPropagator.
+type TextMapCarrier interface {
+	// Get returns the value associated with the passed key.
+	Get(key string) string
+	// Set stores the key-value pair.
+	Set(key string, value string)
+}
+
+// TextMapPropagator propagates cross-cutting concerns as key-value text
+// pairs within a carrier that travels in-band across process boundaries.
+type TextMapPropagator interface {
+	// Inject set cross-cutting concerns from the Context into the carrier.
+	Inject(ctx context.Context, carrier TextMapCarrier)
+	// Extract reads cross-cutting concerns from the carrier into a Context.
+	Extract(ctx context.Context, carrier TextMapCarrier) context.Context
+	// Fields returns the keys who's values are set with Inject.
+	Fields() []string
+}
+
+type compositeTextMapPropagator []TextMapPropagator
+
+func (p compositeTextMapPropagator) Inject(ctx context.Context, carrier TextMapCarrier) {
+	for _, i := range p {
+		i.Inject(ctx, carrier)
+	}
+}
+
+func (p compositeTextMapPropagator) Extract(ctx context.Context, carrier TextMapCarrier) context.Context {
+	for _, i := range p {
+		ctx = i.Extract(ctx, carrier)
+	}
+	return ctx
+}
+
+func (p compositeTextMapPropagator) Fields() []string {
+	unique := make(map[string]struct{})
+	for _, i := range p {
+		for _, k := range i.Fields() {
+			unique[k] = struct{}{}
+		}
+	}
+
+	fields := make([]string, 0, len(unique))
+	for k := range unique {
+		fields = append(fields, k)
+	}
+	return fields
+}
+
+// NewCompositeTextMapPropagator returns a unified TextMapPropagator from the
+// group of passed TextMapPropagator. This allows different cross-cutting
+// concerns to be propagates in a unified manner.
+//
+// The returned TextMapPropagator will inject and extract cross-cutting
+// concerns in the order the TextMapPropagators were provided. Additionally,
+// the Fields method will return a de-duplicated slice of the keys that are
+// set with the Inject method.
+func NewCompositeTextMapPropagator(p ...TextMapPropagator) TextMapPropagator {
+	return compositeTextMapPropagator(p)
+}
diff --git a/vendor/go.opentelemetry.io/otel/tag.sh b/vendor/go.opentelemetry.io/otel/tag.sh
new file mode 100644
index 0000000..70767c7
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/tag.sh
@@ -0,0 +1,178 @@
+#!/usr/bin/env bash
+
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+readonly PROGNAME=$(basename "$0")
+readonly PROGDIR=$(readlink -m "$(dirname "$0")")
+
+readonly EXCLUDE_PACKAGES="internal/tools"
+readonly SEMVER_REGEX="v(0|[1-9][0-9]*)\\.(0|[1-9][0-9]*)\\.(0|[1-9][0-9]*)(\\-[0-9A-Za-z-]+(\\.[0-9A-Za-z-]+)*)?(\\+[0-9A-Za-z-]+(\\.[0-9A-Za-z-]+)*)?"
+
+usage() {
+    cat <<- EOF
+Usage: $PROGNAME [OPTIONS] SEMVER_TAG COMMIT_HASH
+
+Creates git tag for all Go packages in project.
+
+OPTIONS:
+  -h --help        Show this help.
+
+ARGUMENTS:
+  SEMVER_TAG       Semantic version to tag with.
+  COMMIT_HASH      Git commit hash to tag.
+EOF
+}
+
+cmdline() {
+    local arg commit
+
+    for arg
+    do
+        local delim=""
+        case "$arg" in
+            # Translate long form options to short form.
+            --help)           args="${args}-h ";;
+            # Pass through for everything else.
+            *) [[ "${arg:0:1}" == "-" ]] || delim="\""
+                args="${args}${delim}${arg}${delim} ";;
+        esac
+    done
+
+    # Reset and process short form options.
+    eval set -- "$args"
+
+    while getopts "h" OPTION
+    do
+         case $OPTION in
+         h)
+             usage
+             exit 0
+             ;;
+         *)
+             echo "unknown option: $OPTION"
+             usage
+             exit 1
+             ;;
+        esac
+    done
+
+    # Positional arguments.
+    shift $((OPTIND-1))
+    readonly TAG="$1"
+    if [ -z "$TAG" ]
+    then
+        echo "missing SEMVER_TAG"
+        usage
+        exit 1
+    fi
+    if [[ ! "$TAG" =~ $SEMVER_REGEX ]]
+    then
+        printf "invalid semantic version: %s\n" "$TAG"
+        exit 2
+    fi
+    if [[ "$( git tag --list "$TAG" )" ]]
+    then
+        printf "tag already exists: %s\n" "$TAG"
+        exit 2
+    fi
+
+    shift
+    commit="$1"
+    if [ -z "$commit" ]
+    then
+        echo "missing COMMIT_HASH"
+        usage
+        exit 1
+    fi
+    # Verify rev is for a commit and unify hashes into a complete SHA1.
+    readonly SHA="$( git rev-parse --quiet --verify "${commit}^{commit}" )"
+    if [ -z "$SHA" ]
+    then
+        printf "invalid commit hash: %s\n" "$commit"
+        exit 2
+    fi
+    if [ "$( git merge-base "$SHA" HEAD )" != "$SHA" ]
+    then
+        printf "commit '%s' not found on this branch\n" "$commit"
+        exit 2
+    fi
+}
+
+package_dirs() {
+    # Return a list of package directories in the form:
+    #
+    #  package/directory/a
+    #  package/directory/b
+    #  deeper/package/directory/a
+    #  ...
+    #
+    # Making sure to exclude any packages in the EXCLUDE_PACKAGES regexp.
+    find . -mindepth 2 -type f -name 'go.mod' -exec dirname {} \; \
+        | grep -E -v "$EXCLUDE_PACKAGES" \
+        | sed 's/^\.\///' \
+        | sort
+}
+
+git_tag() {
+    local tag="$1"
+    local commit="$2"
+
+    git tag -a "$tag" -s -m "Version $tag" "$commit"
+}
+
+previous_version() {
+    local current="$1"
+
+    # Requires git > 2.0
+    git tag -l --sort=v:refname \
+        | grep -E "^${SEMVER_REGEX}$" \
+        | grep -v "$current" \
+        | tail -1
+}
+
+print_changes() {
+    local tag="$1"
+    local previous
+
+    previous="$( previous_version "$tag" )"
+    if [ -n "$previous" ]
+    then
+        printf "\nRaw changes made between %s and %s\n" "$previous" "$tag"
+        printf "======================================\n"
+        git --no-pager log --pretty=oneline "${previous}..$tag"
+    fi
+}
+
+main() {
+    local dir
+
+    cmdline "$@"
+
+    cd "$PROGDIR" || exit 3
+
+    # Create tag for root package.
+    git_tag "$TAG" "$SHA"
+    printf "created tag: %s\n" "$TAG"
+
+    # Create tag for all sub-packages.
+    for dir in $( package_dirs )
+    do
+        git_tag "${dir}/$TAG" "$SHA"
+        printf "created tag: %s\n" "${dir}/$TAG"
+    done
+
+    print_changes "$TAG"
+}
+main "$@"
diff --git a/vendor/go.opentelemetry.io/otel/unit/doc.go b/vendor/go.opentelemetry.io/otel/unit/doc.go
new file mode 100644
index 0000000..310a7b2
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/unit/doc.go
@@ -0,0 +1,16 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package unit provides units.
+package unit // import "go.opentelemetry.io/otel/unit"
diff --git a/vendor/go.opentelemetry.io/otel/unit/unit.go b/vendor/go.opentelemetry.io/otel/unit/unit.go
new file mode 100644
index 0000000..dcd39af
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/unit/unit.go
@@ -0,0 +1,23 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package unit
+
+type Unit string
+
+const (
+	Dimensionless Unit = "1"
+	Bytes         Unit = "By"
+	Milliseconds  Unit = "ms"
+)
diff --git a/vendor/go.opentelemetry.io/otel/verify_examples.sh b/vendor/go.opentelemetry.io/otel/verify_examples.sh
new file mode 100644
index 0000000..dbb61a4
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/verify_examples.sh
@@ -0,0 +1,85 @@
+#!/bin/bash
+
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -euo pipefail
+
+cd $(dirname $0)
+TOOLS_DIR=$(pwd)/.tools
+
+if [ -z "${GOPATH}" ] ; then
+	printf "GOPATH is not defined.\n"
+	exit -1
+fi
+
+if [ ! -d "${GOPATH}" ] ; then
+	printf "GOPATH ${GOPATH} is invalid \n"
+	exit -1
+fi
+
+# Pre-requisites
+if ! git diff --quiet; then \
+	git status
+	printf "\n\nError: working tree is not clean\n"
+	exit -1
+fi
+
+if [ "$(git tag --contains $(git log -1 --pretty=format:"%H"))" = "" ] ; then
+	printf "$(git log -1)"
+	printf "\n\nError: HEAD is not pointing to a tagged version"
+fi
+
+make ${TOOLS_DIR}/gojq
+
+DIR_TMP="${GOPATH}/src/oteltmp/"
+rm -rf $DIR_TMP
+mkdir -p $DIR_TMP
+
+printf "Copy examples to ${DIR_TMP}\n"
+cp -a ./example ${DIR_TMP}
+
+# Update go.mod files
+printf "Update go.mod: rename module and remove replace\n"
+
+PACKAGE_DIRS=$(find . -mindepth 2 -type f -name 'go.mod' -exec dirname {} \; | egrep 'example' | sed 's/^\.\///' | sort)
+
+for dir in $PACKAGE_DIRS; do
+	printf "  Update go.mod for $dir\n"
+	(cd "${DIR_TMP}/${dir}" && \
+	 # replaces is ("mod1" "mod2" …)
+	 replaces=($(go mod edit -json | ${TOOLS_DIR}/gojq '.Replace[].Old.Path')) && \
+	 # strip double quotes
+	 replaces=("${replaces[@]%\"}") && \
+	 replaces=("${replaces[@]#\"}") && \
+	 # make an array (-dropreplace=mod1 -dropreplace=mod2 …)
+	 dropreplaces=("${replaces[@]/#/-dropreplace=}") && \
+	 go mod edit -module "oteltmp/${dir}" "${dropreplaces[@]}" && \
+	 go mod tidy)
+done
+printf "Update done:\n\n"
+
+# Build directories that contain main package. These directories are different than
+# directories that contain go.mod files.
+printf "Build examples:\n"
+EXAMPLES=$(./get_main_pkgs.sh ./example)
+for ex in $EXAMPLES; do
+	printf "  Build $ex in ${DIR_TMP}/${ex}\n"
+	(cd "${DIR_TMP}/${ex}" && \
+	 go build .)
+done
+
+# Cleanup
+printf "Remove copied files.\n"
+rm -rf $DIR_TMP