diff --git a/vendor/github.com/opentracing/opentracing-go/span.go b/vendor/github.com/opentracing/opentracing-go/span.go
new file mode 100644
index 0000000..0d3fb53
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/span.go
@@ -0,0 +1,189 @@
+package opentracing
+
+import (
+	"time"
+
+	"github.com/opentracing/opentracing-go/log"
+)
+
+// SpanContext represents Span state that must propagate to descendant Spans and across process
+// boundaries (e.g., a <trace_id, span_id, sampled> tuple).
+type SpanContext interface {
+	// ForeachBaggageItem grants access to all baggage items stored in the
+	// SpanContext.
+	// The handler function will be called for each baggage key/value pair.
+	// The ordering of items is not guaranteed.
+	//
+	// The bool return value indicates if the handler wants to continue iterating
+	// through the rest of the baggage items; for example if the handler is trying to
+	// find some baggage item by pattern matching the name, it can return false
+	// as soon as the item is found to stop further iterations.
+	ForeachBaggageItem(handler func(k, v string) bool)
+}
+
+// Span represents an active, un-finished span in the OpenTracing system.
+//
+// Spans are created by the Tracer interface.
+type Span interface {
+	// Sets the end timestamp and finalizes Span state.
+	//
+	// With the exception of calls to Context() (which are always allowed),
+	// Finish() must be the last call made to any span instance, and to do
+	// otherwise leads to undefined behavior.
+	Finish()
+	// FinishWithOptions is like Finish() but with explicit control over
+	// timestamps and log data.
+	FinishWithOptions(opts FinishOptions)
+
+	// Context() yields the SpanContext for this Span. Note that the return
+	// value of Context() is still valid after a call to Span.Finish(), as is
+	// a call to Span.Context() after a call to Span.Finish().
+	Context() SpanContext
+
+	// Sets or changes the operation name.
+	//
+	// Returns a reference to this Span for chaining.
+	SetOperationName(operationName string) Span
+
+	// Adds a tag to the span.
+	//
+	// If there is a pre-existing tag set for `key`, it is overwritten.
+	//
+	// Tag values can be numeric types, strings, or bools. The behavior of
+	// other tag value types is undefined at the OpenTracing level. If a
+	// tracing system does not know how to handle a particular value type, it
+	// may ignore the tag, but shall not panic.
+	//
+	// Returns a reference to this Span for chaining.
+	SetTag(key string, value interface{}) Span
+
+	// LogFields is an efficient and type-checked way to record key:value
+	// logging data about a Span, though the programming interface is a little
+	// more verbose than LogKV(). Here's an example:
+	//
+	//    span.LogFields(
+	//        log.String("event", "soft error"),
+	//        log.String("type", "cache timeout"),
+	//        log.Int("waited.millis", 1500))
+	//
+	// Also see Span.FinishWithOptions() and FinishOptions.BulkLogData.
+	LogFields(fields ...log.Field)
+
+	// LogKV is a concise, readable way to record key:value logging data about
+	// a Span, though unfortunately this also makes it less efficient and less
+	// type-safe than LogFields(). Here's an example:
+	//
+	//    span.LogKV(
+	//        "event", "soft error",
+	//        "type", "cache timeout",
+	//        "waited.millis", 1500)
+	//
+	// For LogKV (as opposed to LogFields()), the parameters must appear as
+	// key-value pairs, like
+	//
+	//    span.LogKV(key1, val1, key2, val2, key3, val3, ...)
+	//
+	// The keys must all be strings. The values may be strings, numeric types,
+	// bools, Go error instances, or arbitrary structs.
+	//
+	// (Note to implementors: consider the log.InterleavedKVToFields() helper)
+	LogKV(alternatingKeyValues ...interface{})
+
+	// SetBaggageItem sets a key:value pair on this Span and its SpanContext
+	// that also propagates to descendants of this Span.
+	//
+	// SetBaggageItem() enables powerful functionality given a full-stack
+	// opentracing integration (e.g., arbitrary application data from a mobile
+	// app can make it, transparently, all the way into the depths of a storage
+	// system), and with it some powerful costs: use this feature with care.
+	//
+	// IMPORTANT NOTE #1: SetBaggageItem() will only propagate baggage items to
+	// *future* causal descendants of the associated Span.
+	//
+	// IMPORTANT NOTE #2: Use this thoughtfully and with care. Every key and
+	// value is copied into every local *and remote* child of the associated
+	// Span, and that can add up to a lot of network and cpu overhead.
+	//
+	// Returns a reference to this Span for chaining.
+	SetBaggageItem(restrictedKey, value string) Span
+
+	// Gets the value for a baggage item given its key. Returns the empty string
+	// if the value isn't found in this Span.
+	BaggageItem(restrictedKey string) string
+
+	// Provides access to the Tracer that created this Span.
+	Tracer() Tracer
+
+	// Deprecated: use LogFields or LogKV
+	LogEvent(event string)
+	// Deprecated: use LogFields or LogKV
+	LogEventWithPayload(event string, payload interface{})
+	// Deprecated: use LogFields or LogKV
+	Log(data LogData)
+}
+
+// LogRecord is data associated with a single Span log. Every LogRecord
+// instance must specify at least one Field.
+type LogRecord struct {
+	Timestamp time.Time
+	Fields    []log.Field
+}
+
+// FinishOptions allows Span.FinishWithOptions callers to override the finish
+// timestamp and provide log data via a bulk interface.
+type FinishOptions struct {
+	// FinishTime overrides the Span's finish time, or implicitly becomes
+	// time.Now() if FinishTime.IsZero().
+	//
+	// FinishTime must resolve to a timestamp that's >= the Span's StartTime
+	// (per StartSpanOptions).
+	FinishTime time.Time
+
+	// LogRecords allows the caller to specify the contents of many LogFields()
+	// calls with a single slice. May be nil.
+	//
+	// None of the LogRecord.Timestamp values may be .IsZero() (i.e., they must
+	// be set explicitly). Also, they must be >= the Span's start timestamp and
+	// <= the FinishTime (or time.Now() if FinishTime.IsZero()). Otherwise the
+	// behavior of FinishWithOptions() is undefined.
+	//
+	// If specified, the caller hands off ownership of LogRecords at
+	// FinishWithOptions() invocation time.
+	//
+	// If specified, the (deprecated) BulkLogData must be nil or empty.
+	LogRecords []LogRecord
+
+	// BulkLogData is DEPRECATED.
+	BulkLogData []LogData
+}
+
+// LogData is DEPRECATED
+type LogData struct {
+	Timestamp time.Time
+	Event     string
+	Payload   interface{}
+}
+
+// ToLogRecord converts a deprecated LogData to a non-deprecated LogRecord
+func (ld *LogData) ToLogRecord() LogRecord {
+	var literalTimestamp time.Time
+	if ld.Timestamp.IsZero() {
+		literalTimestamp = time.Now()
+	} else {
+		literalTimestamp = ld.Timestamp
+	}
+	rval := LogRecord{
+		Timestamp: literalTimestamp,
+	}
+	if ld.Payload == nil {
+		rval.Fields = []log.Field{
+			log.String("event", ld.Event),
+		}
+	} else {
+		rval.Fields = []log.Field{
+			log.String("event", ld.Event),
+			log.Object("payload", ld.Payload),
+		}
+	}
+	return rval
+}