diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/context.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/context.go
new file mode 100644
index 0000000..583025c
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/context.go
@@ -0,0 +1,78 @@
+package grpc_ctxtags
+
+import (
+	"context"
+)
+
+type ctxMarker struct{}
+
+var (
+	// ctxMarkerKey is the Context value marker used by *all* logging middleware.
+	// The logging middleware object must interf
+	ctxMarkerKey = &ctxMarker{}
+	// NoopTags is a trivial, minimum overhead implementation of Tags for which all operations are no-ops.
+	NoopTags = &noopTags{}
+)
+
+// Tags is the interface used for storing request tags between Context calls.
+// The default implementation is *not* thread safe, and should be handled only in the context of the request.
+type Tags interface {
+	// Set sets the given key in the metadata tags.
+	Set(key string, value interface{}) Tags
+	// Has checks if the given key exists.
+	Has(key string) bool
+	// Values returns a map of key to values.
+	// Do not modify the underlying map, please use Set instead.
+	Values() map[string]interface{}
+}
+
+type mapTags struct {
+	values map[string]interface{}
+}
+
+func (t *mapTags) Set(key string, value interface{}) Tags {
+	t.values[key] = value
+	return t
+}
+
+func (t *mapTags) Has(key string) bool {
+	_, ok := t.values[key]
+	return ok
+}
+
+func (t *mapTags) Values() map[string]interface{} {
+	return t.values
+}
+
+type noopTags struct{}
+
+func (t *noopTags) Set(key string, value interface{}) Tags {
+	return t
+}
+
+func (t *noopTags) Has(key string) bool {
+	return false
+}
+
+func (t *noopTags) Values() map[string]interface{} {
+	return nil
+}
+
+// Extracts returns a pre-existing Tags object in the Context.
+// If the context wasn't set in a tag interceptor, a no-op Tag storage is returned that will *not* be propagated in context.
+func Extract(ctx context.Context) Tags {
+	t, ok := ctx.Value(ctxMarkerKey).(Tags)
+	if !ok {
+		return NoopTags
+	}
+
+	return t
+}
+
+func setInContext(ctx context.Context, tags Tags) context.Context {
+	return context.WithValue(ctx, ctxMarkerKey, tags)
+}
+
+func newTags() Tags {
+	return &mapTags{values: make(map[string]interface{})}
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/doc.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/doc.go
new file mode 100644
index 0000000..960638d
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/doc.go
@@ -0,0 +1,22 @@
+/*
+`grpc_ctxtags` adds a Tag object to the context that can be used by other middleware to add context about a request.
+
+Request Context Tags
+
+Tags describe information about the request, and can be set and used by other middleware, or handlers. Tags are used
+for logging and tracing of requests. Tags are populated both upwards, *and* downwards in the interceptor-handler stack.
+
+You can automatically extract tags (in `grpc.request.<field_name>`) from request payloads.
+
+For unary and server-streaming methods, pass in the `WithFieldExtractor` option. For client-streams and bidirectional-streams, you can
+use `WithFieldExtractorForInitialReq` which will extract the tags from the first message passed from client to server.
+Note the tags will not be modified for subsequent requests, so this option only makes sense when the initial message
+establishes the meta-data for the stream.
+
+If a user doesn't use the interceptors that initialize the `Tags` object, all operations following from an `Extract(ctx)`
+will be no-ops. This is to ensure that code doesn't panic if the interceptors weren't used.
+
+Tags fields are typed, and shallow and should follow the OpenTracing semantics convention:
+https://github.com/opentracing/specification/blob/master/semantic_conventions.md
+*/
+package grpc_ctxtags
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/fieldextractor.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/fieldextractor.go
new file mode 100644
index 0000000..549ff48
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/fieldextractor.go
@@ -0,0 +1,85 @@
+// Copyright 2017 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_ctxtags
+
+import (
+	"reflect"
+)
+
+// RequestFieldExtractorFunc is a user-provided function that extracts field information from a gRPC request.
+// It is called from tags middleware on arrival of unary request or a server-stream request.
+// Keys and values will be added to the context tags of the request. If there are no fields, you should return a nil.
+type RequestFieldExtractorFunc func(fullMethod string, req interface{}) map[string]interface{}
+
+type requestFieldsExtractor interface {
+	// ExtractRequestFields is a method declared on a Protobuf message that extracts fields from the interface.
+	// The values from the extracted fields should be set in the appendToMap, in order to avoid allocations.
+	ExtractRequestFields(appendToMap map[string]interface{})
+}
+
+// CodeGenRequestFieldExtractor is a function that relies on code-generated functions that export log fields from requests.
+// These are usually coming from a protoc-plugin that generates additional information based on custom field options.
+func CodeGenRequestFieldExtractor(fullMethod string, req interface{}) map[string]interface{} {
+	if ext, ok := req.(requestFieldsExtractor); ok {
+		retMap := make(map[string]interface{})
+		ext.ExtractRequestFields(retMap)
+		if len(retMap) == 0 {
+			return nil
+		}
+		return retMap
+	}
+	return nil
+}
+
+// TagBasedRequestFieldExtractor is a function that relies on Go struct tags to export log fields from requests.
+// These are usually coming from a protoc-plugin, such as Gogo protobuf.
+//
+//  message Metadata {
+//     repeated string tags = 1 [ (gogoproto.moretags) = "log_field:\"meta_tags\"" ];
+//  }
+//
+// The tagName is configurable using the tagName variable. Here it would be "log_field".
+func TagBasedRequestFieldExtractor(tagName string) RequestFieldExtractorFunc {
+	return func(fullMethod string, req interface{}) map[string]interface{} {
+		retMap := make(map[string]interface{})
+		reflectMessageTags(req, retMap, tagName)
+		if len(retMap) == 0 {
+			return nil
+		}
+		return retMap
+	}
+}
+
+func reflectMessageTags(msg interface{}, existingMap map[string]interface{}, tagName string) {
+	v := reflect.ValueOf(msg)
+	// Only deal with pointers to structs.
+	if v.Kind() != reflect.Ptr || v.Elem().Kind() != reflect.Struct {
+		return
+	}
+	// Deref the pointer get to the struct.
+	v = v.Elem()
+	t := v.Type()
+	for i := 0; i < v.NumField(); i++ {
+		field := v.Field(i)
+		kind := field.Kind()
+		// Only recurse down direct pointers, which should only be to nested structs.
+		if kind == reflect.Ptr {
+			reflectMessageTags(field.Interface(), existingMap, tagName)
+		}
+		// In case of arrays/splices (repeated fields) go down to the concrete type.
+		if kind == reflect.Array || kind == reflect.Slice {
+			if field.Len() == 0 {
+				continue
+			}
+			kind = field.Index(0).Kind()
+		}
+		// Only be interested in
+		if (kind >= reflect.Bool && kind <= reflect.Float64) || kind == reflect.String {
+			if tag := t.Field(i).Tag.Get(tagName); tag != "" {
+				existingMap[tag] = field.Interface()
+			}
+		}
+	}
+	return
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/interceptors.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/interceptors.go
new file mode 100644
index 0000000..038afd2
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/interceptors.go
@@ -0,0 +1,83 @@
+// Copyright 2017 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_ctxtags
+
+import (
+	"github.com/grpc-ecosystem/go-grpc-middleware"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/peer"
+)
+
+// UnaryServerInterceptor returns a new unary server interceptors that sets the values for request tags.
+func UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor {
+	o := evaluateOptions(opts)
+	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+		newCtx := newTagsForCtx(ctx)
+		if o.requestFieldsFunc != nil {
+			setRequestFieldTags(newCtx, o.requestFieldsFunc, info.FullMethod, req)
+		}
+		return handler(newCtx, req)
+	}
+}
+
+// StreamServerInterceptor returns a new streaming server interceptor that sets the values for request tags.
+func StreamServerInterceptor(opts ...Option) grpc.StreamServerInterceptor {
+	o := evaluateOptions(opts)
+	return func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+		newCtx := newTagsForCtx(stream.Context())
+		if o.requestFieldsFunc == nil {
+			// Short-circuit, don't do the expensive bit of allocating a wrappedStream.
+			wrappedStream := grpc_middleware.WrapServerStream(stream)
+			wrappedStream.WrappedContext = newCtx
+			return handler(srv, wrappedStream)
+		}
+		wrapped := &wrappedStream{stream, info, o, newCtx, true}
+		err := handler(srv, wrapped)
+		return err
+	}
+}
+
+// wrappedStream is a thin wrapper around grpc.ServerStream that allows modifying context and extracts log fields from the initial message.
+type wrappedStream struct {
+	grpc.ServerStream
+	info *grpc.StreamServerInfo
+	opts *options
+	// WrappedContext is the wrapper's own Context. You can assign it.
+	WrappedContext context.Context
+	initial        bool
+}
+
+// Context returns the wrapper's WrappedContext, overwriting the nested grpc.ServerStream.Context()
+func (w *wrappedStream) Context() context.Context {
+	return w.WrappedContext
+}
+
+func (w *wrappedStream) RecvMsg(m interface{}) error {
+	err := w.ServerStream.RecvMsg(m)
+	// We only do log fields extraction on the single-request of a server-side stream.
+	if !w.info.IsClientStream || w.opts.requestFieldsFromInitial && w.initial {
+		w.initial = false
+
+		setRequestFieldTags(w.Context(), w.opts.requestFieldsFunc, w.info.FullMethod, m)
+	}
+	return err
+}
+
+func newTagsForCtx(ctx context.Context) context.Context {
+	t := newTags()
+	if peer, ok := peer.FromContext(ctx); ok {
+		t.Set("peer.address", peer.Addr.String())
+	}
+	return setInContext(ctx, t)
+}
+
+func setRequestFieldTags(ctx context.Context, f RequestFieldExtractorFunc, fullMethodName string, req interface{}) {
+	if valMap := f(fullMethodName, req); valMap != nil {
+		t := Extract(ctx)
+		for k, v := range valMap {
+			t.Set("grpc.request."+k, v)
+		}
+	}
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/options.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/options.go
new file mode 100644
index 0000000..952775f
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/options.go
@@ -0,0 +1,44 @@
+// Copyright 2017 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_ctxtags
+
+var (
+	defaultOptions = &options{
+		requestFieldsFunc: nil,
+	}
+)
+
+type options struct {
+	requestFieldsFunc        RequestFieldExtractorFunc
+	requestFieldsFromInitial bool
+}
+
+func evaluateOptions(opts []Option) *options {
+	optCopy := &options{}
+	*optCopy = *defaultOptions
+	for _, o := range opts {
+		o(optCopy)
+	}
+	return optCopy
+}
+
+type Option func(*options)
+
+// WithFieldExtractor customizes the function for extracting log fields from protobuf messages, for
+// unary and server-streamed methods only.
+func WithFieldExtractor(f RequestFieldExtractorFunc) Option {
+	return func(o *options) {
+		o.requestFieldsFunc = f
+	}
+}
+
+// WithFieldExtractorForInitialReq customizes the function for extracting log fields from protobuf messages,
+// for all unary and streaming methods. For client-streams and bidirectional-streams, the tags will be
+// extracted from the first message from the client.
+func WithFieldExtractorForInitialReq(f RequestFieldExtractorFunc) Option {
+	return func(o *options) {
+		o.requestFieldsFunc = f
+		o.requestFieldsFromInitial = true
+	}
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/client_interceptors.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/client_interceptors.go
new file mode 100644
index 0000000..f8fdecf
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/client_interceptors.go
@@ -0,0 +1,142 @@
+// Copyright 2017 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_opentracing
+
+import (
+	"io"
+	"sync"
+
+	"github.com/grpc-ecosystem/go-grpc-middleware/util/metautils"
+	opentracing "github.com/opentracing/opentracing-go"
+	"github.com/opentracing/opentracing-go/ext"
+	"github.com/opentracing/opentracing-go/log"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/metadata"
+)
+
+// UnaryClientInterceptor returns a new unary client interceptor for OpenTracing.
+func UnaryClientInterceptor(opts ...Option) grpc.UnaryClientInterceptor {
+	o := evaluateOptions(opts)
+	return func(parentCtx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+		if o.filterOutFunc != nil && !o.filterOutFunc(parentCtx, method) {
+			return invoker(parentCtx, method, req, reply, cc, opts...)
+		}
+		newCtx, clientSpan := newClientSpanFromContext(parentCtx, o.tracer, method)
+		err := invoker(newCtx, method, req, reply, cc, opts...)
+		finishClientSpan(clientSpan, err)
+		return err
+	}
+}
+
+// StreamClientInterceptor returns a new streaming client interceptor for OpenTracing.
+func StreamClientInterceptor(opts ...Option) grpc.StreamClientInterceptor {
+	o := evaluateOptions(opts)
+	return func(parentCtx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
+		if o.filterOutFunc != nil && !o.filterOutFunc(parentCtx, method) {
+			return streamer(parentCtx, desc, cc, method, opts...)
+		}
+		newCtx, clientSpan := newClientSpanFromContext(parentCtx, o.tracer, method)
+		clientStream, err := streamer(newCtx, desc, cc, method, opts...)
+		if err != nil {
+			finishClientSpan(clientSpan, err)
+			return nil, err
+		}
+		return &tracedClientStream{ClientStream: clientStream, clientSpan: clientSpan}, nil
+	}
+}
+
+// type serverStreamingRetryingStream is the implementation of grpc.ClientStream that acts as a
+// proxy to the underlying call. If any of the RecvMsg() calls fail, it will try to reestablish
+// a new ClientStream according to the retry policy.
+type tracedClientStream struct {
+	grpc.ClientStream
+	mu              sync.Mutex
+	alreadyFinished bool
+	clientSpan      opentracing.Span
+}
+
+func (s *tracedClientStream) Header() (metadata.MD, error) {
+	h, err := s.ClientStream.Header()
+	if err != nil {
+		s.finishClientSpan(err)
+	}
+	return h, err
+}
+
+func (s *tracedClientStream) SendMsg(m interface{}) error {
+	err := s.ClientStream.SendMsg(m)
+	if err != nil {
+		s.finishClientSpan(err)
+	}
+	return err
+}
+
+func (s *tracedClientStream) CloseSend() error {
+	err := s.ClientStream.CloseSend()
+	if err != nil {
+		s.finishClientSpan(err)
+	}
+	return err
+}
+
+func (s *tracedClientStream) RecvMsg(m interface{}) error {
+	err := s.ClientStream.RecvMsg(m)
+	if err != nil {
+		s.finishClientSpan(err)
+	}
+	return err
+}
+
+func (s *tracedClientStream) finishClientSpan(err error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if !s.alreadyFinished {
+		finishClientSpan(s.clientSpan, err)
+		s.alreadyFinished = true
+	}
+}
+
+// ClientAddContextTags returns a context with specified opentracing tags, which
+// are used by UnaryClientInterceptor/StreamClientInterceptor when creating a
+// new span.
+func ClientAddContextTags(ctx context.Context, tags opentracing.Tags) context.Context {
+	return context.WithValue(ctx, clientSpanTagKey{}, tags)
+}
+
+type clientSpanTagKey struct{}
+
+func newClientSpanFromContext(ctx context.Context, tracer opentracing.Tracer, fullMethodName string) (context.Context, opentracing.Span) {
+	var parentSpanCtx opentracing.SpanContext
+	if parent := opentracing.SpanFromContext(ctx); parent != nil {
+		parentSpanCtx = parent.Context()
+	}
+	opts := []opentracing.StartSpanOption{
+		opentracing.ChildOf(parentSpanCtx),
+		ext.SpanKindRPCClient,
+		grpcTag,
+	}
+	if tagx := ctx.Value(clientSpanTagKey{}); tagx != nil {
+		if opt, ok := tagx.(opentracing.StartSpanOption); ok {
+			opts = append(opts, opt)
+		}
+	}
+	clientSpan := tracer.StartSpan(fullMethodName, opts...)
+	// Make sure we add this to the metadata of the call, so it gets propagated:
+	md := metautils.ExtractOutgoing(ctx).Clone()
+	if err := tracer.Inject(clientSpan.Context(), opentracing.HTTPHeaders, metadataTextMap(md)); err != nil {
+		grpclog.Printf("grpc_opentracing: failed serializing trace information: %v", err)
+	}
+	ctxWithMetadata := md.ToOutgoing(ctx)
+	return opentracing.ContextWithSpan(ctxWithMetadata, clientSpan), clientSpan
+}
+
+func finishClientSpan(clientSpan opentracing.Span, err error) {
+	if err != nil && err != io.EOF {
+		ext.Error.Set(clientSpan, true)
+		clientSpan.LogFields(log.String("event", "error"), log.String("message", err.Error()))
+	}
+	clientSpan.Finish()
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/doc.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/doc.go
new file mode 100644
index 0000000..7a58efc
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/doc.go
@@ -0,0 +1,22 @@
+// Copyright 2017 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+/*
+`grpc_opentracing` adds OpenTracing
+
+OpenTracing Interceptors
+
+These are both client-side and server-side interceptors for OpenTracing. They are a provider-agnostic, with backends
+such as Zipkin, or Google Stackdriver Trace.
+
+For a service that sends out requests and receives requests, you *need* to use both, otherwise downstream requests will
+not have the appropriate requests propagated.
+
+All server-side spans are tagged with grpc_ctxtags information.
+
+For more information see:
+http://opentracing.io/documentation/
+https://github.com/opentracing/specification/blob/master/semantic_conventions.md
+
+*/
+package grpc_opentracing
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/id_extract.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/id_extract.go
new file mode 100644
index 0000000..d19f3c8
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/id_extract.go
@@ -0,0 +1,67 @@
+package grpc_opentracing
+
+import (
+	"strings"
+
+	grpc_ctxtags "github.com/grpc-ecosystem/go-grpc-middleware/tags"
+	opentracing "github.com/opentracing/opentracing-go"
+	"google.golang.org/grpc/grpclog"
+)
+
+const (
+	TagTraceId           = "trace.traceid"
+	TagSpanId            = "trace.spanid"
+	TagSampled           = "trace.sampled"
+	jaegerNotSampledFlag = "0"
+)
+
+// injectOpentracingIdsToTags writes trace data to ctxtags.
+// This is done in an incredibly hacky way, because the public-facing interface of opentracing doesn't give access to
+// the TraceId and SpanId of the SpanContext. Only the Tracer's Inject/Extract methods know what these are.
+// Most tracers have them encoded as keys with 'traceid' and 'spanid':
+// https://github.com/openzipkin/zipkin-go-opentracing/blob/594640b9ef7e5c994e8d9499359d693c032d738c/propagation_ot.go#L29
+// https://github.com/opentracing/basictracer-go/blob/1b32af207119a14b1b231d451df3ed04a72efebf/propagation_ot.go#L26
+// Jaeger from Uber use one-key schema with next format '{trace-id}:{span-id}:{parent-span-id}:{flags}'
+// https://www.jaegertracing.io/docs/client-libraries/#trace-span-identity
+func injectOpentracingIdsToTags(span opentracing.Span, tags grpc_ctxtags.Tags) {
+	if err := span.Tracer().Inject(span.Context(), opentracing.HTTPHeaders, &tagsCarrier{tags}); err != nil {
+		grpclog.Infof("grpc_opentracing: failed extracting trace info into ctx %v", err)
+	}
+}
+
+// tagsCarrier is a really hacky way of
+type tagsCarrier struct {
+	grpc_ctxtags.Tags
+}
+
+func (t *tagsCarrier) Set(key, val string) {
+	key = strings.ToLower(key)
+	if strings.Contains(key, "traceid") {
+		t.Tags.Set(TagTraceId, val) // this will most likely be base-16 (hex) encoded
+	}
+
+	if strings.Contains(key, "spanid") && !strings.Contains(strings.ToLower(key), "parent") {
+		t.Tags.Set(TagSpanId, val) // this will most likely be base-16 (hex) encoded
+	}
+
+	if strings.Contains(key, "sampled") {
+		switch val {
+		case "true", "false":
+			t.Tags.Set(TagSampled, val)
+		}
+	}
+
+	if key == "uber-trace-id" {
+		parts := strings.Split(val, ":")
+		if len(parts) == 4 {
+			t.Tags.Set(TagTraceId, parts[0])
+			t.Tags.Set(TagSpanId, parts[1])
+
+			if parts[3] != jaegerNotSampledFlag {
+				t.Tags.Set(TagSampled, "true")
+			} else {
+				t.Tags.Set(TagSampled, "false")
+			}
+		}
+	}
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/metadata.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/metadata.go
new file mode 100644
index 0000000..38f251d
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/metadata.go
@@ -0,0 +1,56 @@
+// Copyright 2017 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_opentracing
+
+import (
+	"encoding/base64"
+	"strings"
+
+	"fmt"
+
+	"google.golang.org/grpc/metadata"
+)
+
+const (
+	binHdrSuffix = "-bin"
+)
+
+// metadataTextMap extends a metadata.MD to be an opentracing textmap
+type metadataTextMap metadata.MD
+
+// Set is a opentracing.TextMapReader interface that extracts values.
+func (m metadataTextMap) Set(key, val string) {
+	// gRPC allows for complex binary values to be written.
+	encodedKey, encodedVal := encodeKeyValue(key, val)
+	// The metadata object is a multimap, and previous values may exist, but for opentracing headers, we do not append
+	// we just override.
+	m[encodedKey] = []string{encodedVal}
+}
+
+// ForeachKey is a opentracing.TextMapReader interface that extracts values.
+func (m metadataTextMap) ForeachKey(callback func(key, val string) error) error {
+	for k, vv := range m {
+		for _, v := range vv {
+			if decodedKey, decodedVal, err := metadata.DecodeKeyValue(k, v); err == nil {
+				if err = callback(decodedKey, decodedVal); err != nil {
+					return err
+				}
+			} else {
+				return fmt.Errorf("failed decoding opentracing from gRPC metadata: %v", err)
+			}
+		}
+	}
+	return nil
+}
+
+// encodeKeyValue encodes key and value qualified for transmission via gRPC.
+// note: copy pasted from private values of grpc.metadata
+func encodeKeyValue(k, v string) (string, string) {
+	k = strings.ToLower(k)
+	if strings.HasSuffix(k, binHdrSuffix) {
+		val := base64.StdEncoding.EncodeToString([]byte(v))
+		v = string(val)
+	}
+	return k, v
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/options.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/options.go
new file mode 100644
index 0000000..e75102b
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/options.go
@@ -0,0 +1,55 @@
+// Copyright 2017 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_opentracing
+
+import (
+	"context"
+
+	"github.com/opentracing/opentracing-go"
+)
+
+var (
+	defaultOptions = &options{
+		filterOutFunc: nil,
+		tracer:        nil,
+	}
+)
+
+// FilterFunc allows users to provide a function that filters out certain methods from being traced.
+//
+// If it returns false, the given request will not be traced.
+type FilterFunc func(ctx context.Context, fullMethodName string) bool
+
+type options struct {
+	filterOutFunc FilterFunc
+	tracer        opentracing.Tracer
+}
+
+func evaluateOptions(opts []Option) *options {
+	optCopy := &options{}
+	*optCopy = *defaultOptions
+	for _, o := range opts {
+		o(optCopy)
+	}
+	if optCopy.tracer == nil {
+		optCopy.tracer = opentracing.GlobalTracer()
+	}
+	return optCopy
+}
+
+type Option func(*options)
+
+// WithFilterFunc customizes the function used for deciding whether a given call is traced or not.
+func WithFilterFunc(f FilterFunc) Option {
+	return func(o *options) {
+		o.filterOutFunc = f
+	}
+}
+
+// WithTracer sets a custom tracer to be used for this middleware, otherwise the opentracing.GlobalTracer is used.
+func WithTracer(tracer opentracing.Tracer) Option {
+	return func(o *options) {
+		o.tracer = tracer
+	}
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/server_interceptors.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/server_interceptors.go
new file mode 100644
index 0000000..53764a0
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/server_interceptors.go
@@ -0,0 +1,87 @@
+// Copyright 2017 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_opentracing
+
+import (
+	"github.com/grpc-ecosystem/go-grpc-middleware"
+	"github.com/grpc-ecosystem/go-grpc-middleware/tags"
+	"github.com/grpc-ecosystem/go-grpc-middleware/util/metautils"
+	"github.com/opentracing/opentracing-go"
+	"github.com/opentracing/opentracing-go/ext"
+	"github.com/opentracing/opentracing-go/log"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/grpclog"
+)
+
+var (
+	grpcTag = opentracing.Tag{Key: string(ext.Component), Value: "gRPC"}
+)
+
+// UnaryServerInterceptor returns a new unary server interceptor for OpenTracing.
+func UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor {
+	o := evaluateOptions(opts)
+	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+		if o.filterOutFunc != nil && !o.filterOutFunc(ctx, info.FullMethod) {
+			return handler(ctx, req)
+		}
+		newCtx, serverSpan := newServerSpanFromInbound(ctx, o.tracer, info.FullMethod)
+		resp, err := handler(newCtx, req)
+		finishServerSpan(ctx, serverSpan, err)
+		return resp, err
+	}
+}
+
+// StreamServerInterceptor returns a new streaming server interceptor for OpenTracing.
+func StreamServerInterceptor(opts ...Option) grpc.StreamServerInterceptor {
+	o := evaluateOptions(opts)
+	return func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+		if o.filterOutFunc != nil && !o.filterOutFunc(stream.Context(), info.FullMethod) {
+			return handler(srv, stream)
+		}
+		newCtx, serverSpan := newServerSpanFromInbound(stream.Context(), o.tracer, info.FullMethod)
+		wrappedStream := grpc_middleware.WrapServerStream(stream)
+		wrappedStream.WrappedContext = newCtx
+		err := handler(srv, wrappedStream)
+		finishServerSpan(newCtx, serverSpan, err)
+		return err
+	}
+}
+
+func newServerSpanFromInbound(ctx context.Context, tracer opentracing.Tracer, fullMethodName string) (context.Context, opentracing.Span) {
+	md := metautils.ExtractIncoming(ctx)
+	parentSpanContext, err := tracer.Extract(opentracing.HTTPHeaders, metadataTextMap(md))
+	if err != nil && err != opentracing.ErrSpanContextNotFound {
+		grpclog.Printf("grpc_opentracing: failed parsing trace information: %v", err)
+	}
+
+	serverSpan := tracer.StartSpan(
+		fullMethodName,
+		// this is magical, it attaches the new span to the parent parentSpanContext, and creates an unparented one if empty.
+		ext.RPCServerOption(parentSpanContext),
+		grpcTag,
+	)
+
+	injectOpentracingIdsToTags(serverSpan, grpc_ctxtags.Extract(ctx))
+	return opentracing.ContextWithSpan(ctx, serverSpan), serverSpan
+}
+
+func finishServerSpan(ctx context.Context, serverSpan opentracing.Span, err error) {
+	// Log context information
+	tags := grpc_ctxtags.Extract(ctx)
+	for k, v := range tags.Values() {
+		// Don't tag errors, log them instead.
+		if vErr, ok := v.(error); ok {
+			serverSpan.LogKV(k, vErr.Error())
+
+		} else {
+			serverSpan.SetTag(k, v)
+		}
+	}
+	if err != nil {
+		ext.Error.Set(serverSpan, true)
+		serverSpan.LogFields(log.String("event", "error"), log.String("message", err.Error()))
+	}
+	serverSpan.Finish()
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/doc.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/doc.go
new file mode 100644
index 0000000..1ed9bb4
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/doc.go
@@ -0,0 +1,19 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+/*
+Package `metautils` provides convenience functions for dealing with gRPC metadata.MD objects inside
+Context handlers.
+
+While the upstream grpc-go package contains decent functionality (see https://github.com/grpc/grpc-go/blob/master/Documentation/grpc-metadata.md)
+they are hard to use.
+
+The majority of functions center around the NiceMD, which is a convenience wrapper around metadata.MD. For example
+the following code allows you to easily extract incoming metadata (server handler) and put it into a new client context
+metadata.
+
+  nmd := metautils.ExtractIncoming(serverCtx).Clone(":authorization", ":custom")
+  clientCtx := nmd.Set("x-client-header", "2").Set("x-another", "3").ToOutgoing(ctx)
+*/
+
+package metautils
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/nicemd.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/nicemd.go
new file mode 100644
index 0000000..a277bee
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/nicemd.go
@@ -0,0 +1,126 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package metautils
+
+import (
+	"strings"
+
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/metadata"
+)
+
+// NiceMD is a convenience wrapper definiting extra functions on the metadata.
+type NiceMD metadata.MD
+
+// ExtractIncoming extracts an inbound metadata from the server-side context.
+//
+// This function always returns a NiceMD wrapper of the metadata.MD, in case the context doesn't have metadata it returns
+// a new empty NiceMD.
+func ExtractIncoming(ctx context.Context) NiceMD {
+	md, ok := metadata.FromIncomingContext(ctx)
+	if !ok {
+		return NiceMD(metadata.Pairs())
+	}
+	return NiceMD(md)
+}
+
+// ExtractOutgoing extracts an outbound metadata from the client-side context.
+//
+// This function always returns a NiceMD wrapper of the metadata.MD, in case the context doesn't have metadata it returns
+// a new empty NiceMD.
+func ExtractOutgoing(ctx context.Context) NiceMD {
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if !ok {
+		return NiceMD(metadata.Pairs())
+	}
+	return NiceMD(md)
+}
+
+// Clone performs a *deep* copy of the metadata.MD.
+//
+// You can specify the lower-case copiedKeys to only copy certain whitelisted keys. If no keys are explicitly whitelisted
+// all keys get copied.
+func (m NiceMD) Clone(copiedKeys ...string) NiceMD {
+	newMd := NiceMD(metadata.Pairs())
+	for k, vv := range m {
+		found := false
+		if len(copiedKeys) == 0 {
+			found = true
+		} else {
+			for _, allowedKey := range copiedKeys {
+				if strings.ToLower(allowedKey) == strings.ToLower(k) {
+					found = true
+					break
+				}
+			}
+		}
+		if !found {
+			continue
+		}
+		newMd[k] = make([]string, len(vv))
+		copy(newMd[k], vv)
+	}
+	return NiceMD(newMd)
+}
+
+// ToOutgoing sets the given NiceMD as a client-side context for dispatching.
+func (m NiceMD) ToOutgoing(ctx context.Context) context.Context {
+	return metadata.NewOutgoingContext(ctx, metadata.MD(m))
+}
+
+// ToIncoming sets the given NiceMD as a server-side context for dispatching.
+//
+// This is mostly useful in ServerInterceptors..
+func (m NiceMD) ToIncoming(ctx context.Context) context.Context {
+	return metadata.NewIncomingContext(ctx, metadata.MD(m))
+}
+
+// Get retrieves a single value from the metadata.
+//
+// It works analogously to http.Header.Get, returning the first value if there are many set. If the value is not set,
+// an empty string is returned.
+//
+// The function is binary-key safe.
+func (m NiceMD) Get(key string) string {
+	k, _ := encodeKeyValue(key, "")
+	vv, ok := m[k]
+	if !ok {
+		return ""
+	}
+	return vv[0]
+}
+
+// Del retrieves a single value from the metadata.
+//
+// It works analogously to http.Header.Del, deleting all values if they exist.
+//
+// The function is binary-key safe.
+
+func (m NiceMD) Del(key string) NiceMD {
+	k, _ := encodeKeyValue(key, "")
+	delete(m, k)
+	return m
+}
+
+// Set sets the given value in a metadata.
+//
+// It works analogously to http.Header.Set, overwriting all previous metadata values.
+//
+// The function is binary-key safe.
+func (m NiceMD) Set(key string, value string) NiceMD {
+	k, v := encodeKeyValue(key, value)
+	m[k] = []string{v}
+	return m
+}
+
+// Add retrieves a single value from the metadata.
+//
+// It works analogously to http.Header.Add, as it appends to any existing values associated with key.
+//
+// The function is binary-key safe.
+func (m NiceMD) Add(key string, value string) NiceMD {
+	k, v := encodeKeyValue(key, value)
+	m[k] = append(m[k], v)
+	return m
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/single_key.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/single_key.go
new file mode 100644
index 0000000..8a53871
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/single_key.go
@@ -0,0 +1,22 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package metautils
+
+import (
+	"encoding/base64"
+	"strings"
+)
+
+const (
+	binHdrSuffix = "-bin"
+)
+
+func encodeKeyValue(k, v string) (string, string) {
+	k = strings.ToLower(k)
+	if strings.HasSuffix(k, binHdrSuffix) {
+		val := base64.StdEncoding.EncodeToString([]byte(v))
+		v = string(val)
+	}
+	return k, v
+}