diff --git a/app/multitenant/aws_collector.go b/app/multitenant/aws_collector.go
index 2a32b82c7..51ef9291c 100644
--- a/app/multitenant/aws_collector.go
+++ b/app/multitenant/aws_collector.go
@@ -91,7 +91,7 @@ type AWSCollector interface {
 
 // ReportStore is a thing that we can get reports from.
 type ReportStore interface {
-	FetchReports([]string) (map[string]report.Report, []string, error)
+	FetchReports(context.Context, []string) (map[string]report.Report, []string, error)
 }
 
 // AWSCollectorConfig has everything we need to make an AWS collector.
@@ -215,10 +215,10 @@ func (c *awsCollector) CreateTables() error {
 }
 
 // getReportKeys gets the s3 keys for reports in this range
-func (c *awsCollector) getReportKeys(userid string, row int64, start, end time.Time) ([]string, error) {
+func (c *awsCollector) getReportKeys(ctx context.Context, userid string, row int64, start, end time.Time) ([]string, error) {
 	rowKey := fmt.Sprintf("%s-%s", userid, strconv.FormatInt(row, 10))
 	var resp *dynamodb.QueryOutput
-	err := instrument.TimeRequestHistogram("Query", dynamoRequestDuration, func() error {
+	err := instrument.TimeRequestHistogram(ctx, "DynamoDB.Query", dynamoRequestDuration, func(_ context.Context) error {
 		var err error
 		resp, err = c.db.Query(&dynamodb.QueryInput{
 			TableName: aws.String(c.tableName),
@@ -263,7 +263,7 @@ func (c *awsCollector) getReportKeys(userid string, row int64, start, end time.T
 	return result, nil
 }
 
-func (c *awsCollector) getReports(reportKeys []string) ([]report.Report, error) {
+func (c *awsCollector) getReports(ctx context.Context, reportKeys []string) ([]report.Report, error) {
 	missing := reportKeys
 
 	stores := []ReportStore{c.inProcess}
@@ -277,7 +277,7 @@ func (c *awsCollector) getReports(reportKeys []string) ([]report.Report, error)
 		if store == nil {
 			continue
 		}
-		found, newMissing, err := store.FetchReports(missing)
+		found, newMissing, err := store.FetchReports(ctx, missing)
 		missing = newMissing
 		if err != nil {
 			log.Warningf("Error fetching from cache: %v", err)
@@ -311,12 +311,12 @@ func (c *awsCollector) Report(ctx context.Context) (report.Report, error) {
 	// Queries will only every span 2 rows max.
 	var reportKeys []string
 	if rowStart != rowEnd {
-		reportKeys1, err := c.getReportKeys(userid, rowStart, start, now)
+		reportKeys1, err := c.getReportKeys(ctx, userid, rowStart, start, now)
 		if err != nil {
 			return report.MakeReport(), err
 		}
 
-		reportKeys2, err := c.getReportKeys(userid, rowEnd, start, now)
+		reportKeys2, err := c.getReportKeys(ctx, userid, rowEnd, start, now)
 		if err != nil {
 			return report.MakeReport(), err
 		}
@@ -324,13 +324,13 @@ func (c *awsCollector) Report(ctx context.Context) (report.Report, error) {
 		reportKeys = append(reportKeys, reportKeys1...)
 		reportKeys = append(reportKeys, reportKeys2...)
 	} else {
-		if reportKeys, err = c.getReportKeys(userid, rowEnd, start, now); err != nil {
+		if reportKeys, err = c.getReportKeys(ctx, userid, rowEnd, start, now); err != nil {
 			return report.MakeReport(), err
 		}
 	}
 
 	log.Debugf("Fetching %d reports from %v to %v", len(reportKeys), start, now)
-	reports, err := c.getReports(reportKeys)
+	reports, err := c.getReports(ctx, reportKeys)
 	if err != nil {
 		return report.MakeReport(), err
 	}
@@ -367,7 +367,7 @@ func (c *awsCollector) Add(ctx context.Context, rep report.Report, buf []byte) e
 		return err
 	}
 
-	reportSize, err := c.s3.StoreReportBytes(reportKey, buf)
+	reportSize, err := c.s3.StoreReportBytes(ctx, reportKey, buf)
 	if err != nil {
 		return err
 	}
@@ -375,7 +375,7 @@ func (c *awsCollector) Add(ctx context.Context, rep report.Report, buf []byte) e
 
 	// third, put it in memcache
 	if c.memcache != nil {
-		_, err = c.memcache.StoreReportBytes(reportKey, buf)
+		_, err = c.memcache.StoreReportBytes(ctx, reportKey, buf)
 		if err != nil {
 			// NOTE: We don't abort here because failing to store in memcache
 			// doesn't actually break anything else -- it's just an
@@ -389,7 +389,7 @@ func (c *awsCollector) Add(ctx context.Context, rep report.Report, buf []byte) e
 		Add(float64(len(reportKey)))
 
 	var resp *dynamodb.PutItemOutput
-	err = instrument.TimeRequestHistogram("PutItem", dynamoRequestDuration, func() error {
+	err = instrument.TimeRequestHistogram(ctx, "S3.PutItem", dynamoRequestDuration, func(_ context.Context) error {
 		var err error
 		resp, err = c.db.PutItem(&dynamodb.PutItemInput{
 			TableName: aws.String(c.tableName),
@@ -502,7 +502,7 @@ func newInProcessStore(size int, expiration time.Duration) inProcessStore {
 }
 
 // FetchReports retrieves the given reports from the store.
-func (c inProcessStore) FetchReports(keys []string) (map[string]report.Report, []string, error) {
+func (c inProcessStore) FetchReports(_ context.Context, keys []string) (map[string]report.Report, []string, error) {
 	found := map[string]report.Report{}
 	missing := []string{}
 	for _, key := range keys {
diff --git a/app/multitenant/memcache_client.go b/app/multitenant/memcache_client.go
index 9d3e165cc..4a6218ae6 100644
--- a/app/multitenant/memcache_client.go
+++ b/app/multitenant/memcache_client.go
@@ -11,6 +11,7 @@ import (
 	log "github.com/Sirupsen/logrus"
 	"github.com/bradfitz/gomemcache/memcache"
 	"github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/net/context"
 
 	"github.com/weaveworks/scope/common/instrument"
 	"github.com/weaveworks/scope/report"
@@ -149,10 +150,10 @@ func memcacheStatusCode(err error) string {
 }
 
 // FetchReports gets reports from memcache.
-func (c *MemcacheClient) FetchReports(keys []string) (map[string]report.Report, []string, error) {
+func (c *MemcacheClient) FetchReports(ctx context.Context, keys []string) (map[string]report.Report, []string, error) {
 	defer memcacheRequests.Add(float64(len(keys)))
 	var found map[string]*memcache.Item
-	err := instrument.TimeRequestHistogramStatus("Get", memcacheRequestDuration, memcacheStatusCode, func() error {
+	err := instrument.TimeRequestHistogramStatus(ctx, "Memcache.GetMulti", memcacheRequestDuration, memcacheStatusCode, func(_ context.Context) error {
 		var err error
 		found, err = c.client.GetMulti(keys)
 		return err
@@ -206,8 +207,8 @@ func (c *MemcacheClient) FetchReports(keys []string) (map[string]report.Report,
 }
 
 // StoreReportBytes stores a report.
-func (c *MemcacheClient) StoreReportBytes(key string, rpt []byte) (int, error) {
-	err := instrument.TimeRequestHistogramStatus("Put", memcacheRequestDuration, memcacheStatusCode, func() error {
+func (c *MemcacheClient) StoreReportBytes(ctx context.Context, key string, rpt []byte) (int, error) {
+	err := instrument.TimeRequestHistogramStatus(ctx, "Memcache.Put", memcacheRequestDuration, memcacheStatusCode, func(_ context.Context) error {
 		item := memcache.Item{Key: key, Value: rpt, Expiration: c.expiration}
 		return c.client.Set(&item)
 	})
diff --git a/app/multitenant/s3_client.go b/app/multitenant/s3_client.go
index 99726b196..fcad11745 100644
--- a/app/multitenant/s3_client.go
+++ b/app/multitenant/s3_client.go
@@ -7,6 +7,7 @@ import (
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/net/context"
 
 	"github.com/weaveworks/scope/common/instrument"
 	"github.com/weaveworks/scope/report"
@@ -40,7 +41,7 @@ func NewS3Client(config *aws.Config, bucketName string) S3Store {
 }
 
 // FetchReports fetches multiple reports in parallel from S3.
-func (store *S3Store) FetchReports(keys []string) (map[string]report.Report, []string, error) {
+func (store *S3Store) FetchReports(ctx context.Context, keys []string) (map[string]report.Report, []string, error) {
 	type result struct {
 		key    string
 		report *report.Report
@@ -52,7 +53,7 @@ func (store *S3Store) FetchReports(keys []string) (map[string]report.Report, []s
 	for _, key := range keys {
 		go func(key string) {
 			r := result{key: key}
-			r.report, r.err = store.fetchReport(key)
+			r.report, r.err = store.fetchReport(ctx, key)
 			ch <- r
 		}(key)
 	}
@@ -68,9 +69,9 @@ func (store *S3Store) FetchReports(keys []string) (map[string]report.Report, []s
 	return reports, []string{}, nil
 }
 
-func (store *S3Store) fetchReport(key string) (*report.Report, error) {
+func (store *S3Store) fetchReport(ctx context.Context, key string) (*report.Report, error) {
 	var resp *s3.GetObjectOutput
-	err := instrument.TimeRequestHistogram("Get", s3RequestDuration, func() error {
+	err := instrument.TimeRequestHistogram(ctx, "S3.Get", s3RequestDuration, func(_ context.Context) error {
 		var err error
 		resp, err = store.s3.GetObject(&s3.GetObjectInput{
 			Bucket: aws.String(store.bucketName),
@@ -85,8 +86,8 @@ func (store *S3Store) fetchReport(key string) (*report.Report, error) {
 }
 
 // StoreReportBytes stores a report.
-func (store *S3Store) StoreReportBytes(key string, buf []byte) (int, error) {
-	err := instrument.TimeRequestHistogram("Put", s3RequestDuration, func() error {
+func (store *S3Store) StoreReportBytes(ctx context.Context, key string, buf []byte) (int, error) {
+	err := instrument.TimeRequestHistogram(ctx, "S3.Put", s3RequestDuration, func(_ context.Context) error {
 		_, err := store.s3.PutObject(&s3.PutObjectInput{
 			Body:   bytes.NewReader(buf),
 			Bucket: aws.String(store.bucketName),
diff --git a/app/multitenant/sqs_control_router.go b/app/multitenant/sqs_control_router.go
index 8d1ab2ebc..7df3f3080 100644
--- a/app/multitenant/sqs_control_router.go
+++ b/app/multitenant/sqs_control_router.go
@@ -92,11 +92,11 @@ func (cr *sqsControlRouter) getResponseQueueURL() *string {
 	return cr.responseQueueURL
 }
 
-func (cr *sqsControlRouter) getOrCreateQueue(name string) (*string, error) {
+func (cr *sqsControlRouter) getOrCreateQueue(ctx context.Context, name string) (*string, error) {
 	// CreateQueue creates a queue or if it already exists, returns url of said queue
 	var createQueueRes *sqs.CreateQueueOutput
 	var err error
-	err = instrument.TimeRequestHistogram("CreateQueue", sqsRequestDuration, func() error {
+	err = instrument.TimeRequestHistogram(ctx, "SQS.CreateQueue", sqsRequestDuration, func(_ context.Context) error {
 		createQueueRes, err = cr.service.CreateQueue(&sqs.CreateQueueInput{
 			QueueName: aws.String(name),
 		})
@@ -112,11 +112,12 @@ func (cr *sqsControlRouter) loop() {
 	var (
 		responseQueueURL *string
 		err              error
+		ctx              = context.Background()
 	)
 	for {
 		// This app has a random id and uses this as a return path for all responses from probes.
 		name := fmt.Sprintf("%scontrol-app-%d", cr.prefix, rand.Int63())
-		responseQueueURL, err = cr.getOrCreateQueue(name)
+		responseQueueURL, err = cr.getOrCreateQueue(ctx, name)
 		if err != nil {
 			log.Errorf("Failed to create queue: %v", err)
 			time.Sleep(1 * time.Second)
@@ -129,7 +130,7 @@ func (cr *sqsControlRouter) loop() {
 	for {
 		var res *sqs.ReceiveMessageOutput
 		var err error
-		err = instrument.TimeRequestHistogram("ReceiveMessage", sqsRequestDuration, func() error {
+		err = instrument.TimeRequestHistogram(ctx, "SQS.ReceiveMessage", sqsRequestDuration, func(_ context.Context) error {
 			res, err = cr.service.ReceiveMessage(&sqs.ReceiveMessageInput{
 				QueueUrl:        responseQueueURL,
 				WaitTimeSeconds: longPollTime,
@@ -144,14 +145,14 @@ func (cr *sqsControlRouter) loop() {
 		if len(res.Messages) == 0 {
 			continue
 		}
-		if err := cr.deleteMessages(responseQueueURL, res.Messages); err != nil {
+		if err := cr.deleteMessages(ctx, responseQueueURL, res.Messages); err != nil {
 			log.Errorf("Error deleting message from %s: %v", *responseQueueURL, err)
 		}
 		cr.handleResponses(res)
 	}
 }
 
-func (cr *sqsControlRouter) deleteMessages(queueURL *string, messages []*sqs.Message) error {
+func (cr *sqsControlRouter) deleteMessages(ctx context.Context, queueURL *string, messages []*sqs.Message) error {
 	entries := []*sqs.DeleteMessageBatchRequestEntry{}
 	for _, message := range messages {
 		entries = append(entries, &sqs.DeleteMessageBatchRequestEntry{
@@ -159,7 +160,7 @@ func (cr *sqsControlRouter) deleteMessages(queueURL *string, messages []*sqs.Mes
 			Id:            message.MessageId,
 		})
 	}
-	return instrument.TimeRequestHistogram("DeleteMessageBatch", sqsRequestDuration, func() error {
+	return instrument.TimeRequestHistogram(ctx, "SQS.DeleteMessageBatch", sqsRequestDuration, func(_ context.Context) error {
 		_, err := cr.service.DeleteMessageBatch(&sqs.DeleteMessageBatchInput{
 			QueueUrl: queueURL,
 			Entries:  entries,
@@ -188,14 +189,14 @@ func (cr *sqsControlRouter) handleResponses(res *sqs.ReceiveMessageOutput) {
 	}
 }
 
-func (cr *sqsControlRouter) sendMessage(queueURL *string, message interface{}) error {
+func (cr *sqsControlRouter) sendMessage(ctx context.Context, queueURL *string, message interface{}) error {
 	buf := bytes.Buffer{}
 	if err := json.NewEncoder(&buf).Encode(message); err != nil {
 		return err
 	}
 	log.Infof("sendMessage to %s: %s", *queueURL, buf.String())
 
-	return instrument.TimeRequestHistogram("SendMessage", sqsRequestDuration, func() error {
+	return instrument.TimeRequestHistogram(ctx, "SQS.SendMessage", sqsRequestDuration, func(_ context.Context) error {
 		_, err := cr.service.SendMessage(&sqs.SendMessageInput{
 			QueueUrl:    queueURL,
 			MessageBody: aws.String(buf.String()),
@@ -218,7 +219,7 @@ func (cr *sqsControlRouter) Handle(ctx context.Context, probeID string, req xfer
 	}
 
 	var probeQueueURL *sqs.GetQueueUrlOutput
-	err = instrument.TimeRequestHistogram("GetQueueUrl", sqsRequestDuration, func() error {
+	err = instrument.TimeRequestHistogram(ctx, "SQS.GetQueueUrl", sqsRequestDuration, func(_ context.Context) error {
 		probeQueueName := fmt.Sprintf("%sprobe-%s-%s", cr.prefix, userID, probeID)
 		probeQueueURL, err = cr.service.GetQueueUrl(&sqs.GetQueueUrlInput{
 			QueueName: aws.String(probeQueueName),
@@ -242,8 +243,8 @@ func (cr *sqsControlRouter) Handle(ctx context.Context, probeID string, req xfer
 	}()
 
 	// Next, send the request to that queue
-	if err := instrument.TimeRequestHistogram("SendMessage", sqsRequestDuration, func() error {
-		return cr.sendMessage(probeQueueURL.QueueUrl, sqsRequestMessage{
+	if err := instrument.TimeRequestHistogram(ctx, "SQS.SendMessage", sqsRequestDuration, func(ctx context.Context) error {
+		return cr.sendMessage(ctx, probeQueueURL.QueueUrl, sqsRequestMessage{
 			ID:               id,
 			Request:          req,
 			ResponseQueueURL: *responseQueueURL,
@@ -268,13 +269,14 @@ func (cr *sqsControlRouter) Register(ctx context.Context, probeID string, handle
 	}
 
 	name := fmt.Sprintf("%sprobe-%s-%s", cr.prefix, userID, probeID)
-	queueURL, err := cr.getOrCreateQueue(name)
+	queueURL, err := cr.getOrCreateQueue(ctx, name)
 	if err != nil {
 		return 0, err
 	}
 
 	pwID := rand.Int63()
 	pw := &probeWorker{
+		ctx:             ctx,
 		router:          cr,
 		requestQueueURL: queueURL,
 		handler:         handler,
@@ -302,6 +304,7 @@ func (cr *sqsControlRouter) Deregister(_ context.Context, probeID string, id int
 
 // a probeWorker encapsulates a goroutine serving a probe's websocket connection.
 type probeWorker struct {
+	ctx             context.Context
 	router          *sqsControlRouter
 	requestQueueURL *string
 	handler         xfer.ControlHandlerFunc
@@ -326,7 +329,7 @@ func (pw *probeWorker) loop() {
 
 		var res *sqs.ReceiveMessageOutput
 		var err error
-		err = instrument.TimeRequestHistogram("ReceiveMessage", sqsRequestDuration, func() error {
+		err = instrument.TimeRequestHistogram(pw.ctx, "SQS.ReceiveMessage", sqsRequestDuration, func(_ context.Context) error {
 			res, err = pw.router.service.ReceiveMessage(&sqs.ReceiveMessageInput{
 				QueueUrl:        pw.requestQueueURL,
 				WaitTimeSeconds: longPollTime,
@@ -341,7 +344,7 @@ func (pw *probeWorker) loop() {
 		if len(res.Messages) == 0 {
 			continue
 		}
-		if err := pw.router.deleteMessages(pw.requestQueueURL, res.Messages); err != nil {
+		if err := pw.router.deleteMessages(pw.ctx, pw.requestQueueURL, res.Messages); err != nil {
 			log.Errorf("Error deleting message from %s: %v", *pw.requestQueueURL, err)
 		}
 
@@ -354,7 +357,7 @@ func (pw *probeWorker) loop() {
 
 			response := pw.handler(sqsRequest.Request)
 
-			if err := pw.router.sendMessage(&sqsRequest.ResponseQueueURL, sqsResponseMessage{
+			if err := pw.router.sendMessage(pw.ctx, &sqsRequest.ResponseQueueURL, sqsResponseMessage{
 				ID:       sqsRequest.ID,
 				Response: response,
 			}); err != nil {
diff --git a/common/instrument/instrument.go b/common/instrument/instrument.go
index 96b2dfee0..d90aa90d3 100644
--- a/common/instrument/instrument.go
+++ b/common/instrument/instrument.go
@@ -3,7 +3,10 @@ package instrument
 import (
 	"time"
 
+	"github.com/opentracing/opentracing-go"
+	"github.com/opentracing/opentracing-go/ext"
 	"github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/net/context"
 )
 
 // ErrorCode converts an error in to an http-style error-code.
@@ -16,26 +19,35 @@ func ErrorCode(err error) string {
 
 // TimeRequestHistogram runs 'f' and records how long it took in the given Prometheus
 // histogram metric. If 'f' returns successfully, record a "200". Otherwise, record
-// "500".
+// "500".  It will also emit an OpenTracing span if you have a global tracer configured.
 //
 // If you want more complicated logic for translating errors into statuses,
 // use 'TimeRequestStatus'.
-func TimeRequestHistogram(method string, metric *prometheus.HistogramVec, f func() error) error {
-	return TimeRequestHistogramStatus(method, metric, ErrorCode, f)
+func TimeRequestHistogram(ctx context.Context, method string, metric *prometheus.HistogramVec, f func(context.Context) error) error {
+	return TimeRequestHistogramStatus(ctx, method, metric, ErrorCode, f)
 }
 
 // TimeRequestHistogramStatus runs 'f' and records how long it took in the given
-// Prometheus histogram metric.
+// Prometheus histogram metric.  It will also emit an OpenTracing span if you have
+// a global tracer configured.
 //
 // toStatusCode is a function that translates errors returned by 'f' into
 // HTTP-like status codes.
-func TimeRequestHistogramStatus(method string, metric *prometheus.HistogramVec, toStatusCode func(error) string, f func() error) error {
+func TimeRequestHistogramStatus(ctx context.Context, method string, metric *prometheus.HistogramVec, toStatusCode func(error) string, f func(context.Context) error) error {
 	if toStatusCode == nil {
 		toStatusCode = ErrorCode
 	}
+
+	sp, newCtx := opentracing.StartSpanFromContext(ctx, method)
+	ext.SpanKindRPCClient.Set(sp)
 	startTime := time.Now()
-	err := f()
-	duration := time.Now().Sub(startTime)
-	metric.WithLabelValues(method, toStatusCode(err)).Observe(duration.Seconds())
+
+	err := f(newCtx)
+
+	if err != nil {
+		ext.Error.Set(sp, true)
+	}
+	sp.Finish()
+	metric.WithLabelValues(method, toStatusCode(err)).Observe(time.Now().Sub(startTime).Seconds())
 	return err
 }
diff --git a/vendor/github.com/opentracing/opentracing-go/LICENSE b/vendor/github.com/opentracing/opentracing-go/LICENSE
new file mode 100644
index 000000000..148509a40
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/LICENSE
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2016 The OpenTracing Authors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/vendor/github.com/opentracing/opentracing-go/ext/tags.go b/vendor/github.com/opentracing/opentracing-go/ext/tags.go
new file mode 100644
index 000000000..09f647b5a
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/ext/tags.go
@@ -0,0 +1,158 @@
+package ext
+
+import opentracing "github.com/opentracing/opentracing-go"
+
+// These constants define common tag names recommended for better portability across
+// tracing systems and languages/platforms.
+//
+// The tag names are defined as typed strings, so that in addition to the usual use
+//
+//     span.setTag(TagName, value)
+//
+// they also support value type validation via this additional syntax:
+//
+//    TagName.Set(span, value)
+//
+var (
+	//////////////////////////////////////////////////////////////////////
+	// SpanKind (client/server)
+	//////////////////////////////////////////////////////////////////////
+
+	// SpanKind hints at relationship between spans, e.g. client/server
+	SpanKind = spanKindTagName("span.kind")
+
+	// SpanKindRPCClient marks a span representing the client-side of an RPC
+	// or other remote call
+	SpanKindRPCClientEnum = SpanKindEnum("client")
+	SpanKindRPCClient     = opentracing.Tag{Key: string(SpanKind), Value: SpanKindRPCClientEnum}
+
+	// SpanKindRPCServer marks a span representing the server-side of an RPC
+	// or other remote call
+	SpanKindRPCServerEnum = SpanKindEnum("server")
+	SpanKindRPCServer     = opentracing.Tag{Key: string(SpanKind), Value: SpanKindRPCServerEnum}
+
+	//////////////////////////////////////////////////////////////////////
+	// Component name
+	//////////////////////////////////////////////////////////////////////
+
+	// Component is a low-cardinality identifier of the module, library,
+	// or package that is generating a span.
+	Component = stringTagName("component")
+
+	//////////////////////////////////////////////////////////////////////
+	// Sampling hint
+	//////////////////////////////////////////////////////////////////////
+
+	// SamplingPriority determines the priority of sampling this Span.
+	SamplingPriority = uint16TagName("sampling.priority")
+
+	//////////////////////////////////////////////////////////////////////
+	// Peer tags. These tags can be emitted by either client-side of
+	// server-side to describe the other side/service in a peer-to-peer
+	// communications, like an RPC call.
+	//////////////////////////////////////////////////////////////////////
+
+	// PeerService records the service name of the peer
+	PeerService = stringTagName("peer.service")
+
+	// PeerHostname records the host name of the peer
+	PeerHostname = stringTagName("peer.hostname")
+
+	// PeerHostIPv4 records IP v4 host address of the peer
+	PeerHostIPv4 = uint32TagName("peer.ipv4")
+
+	// PeerHostIPv6 records IP v6 host address of the peer
+	PeerHostIPv6 = stringTagName("peer.ipv6")
+
+	// PeerPort records port number of the peer
+	PeerPort = uint16TagName("peer.port")
+
+	//////////////////////////////////////////////////////////////////////
+	// HTTP Tags
+	//////////////////////////////////////////////////////////////////////
+
+	// HTTPUrl should be the URL of the request being handled in this segment
+	// of the trace, in standard URI format. The protocol is optional.
+	HTTPUrl = stringTagName("http.url")
+
+	// HTTPMethod is the HTTP method of the request, and is case-insensitive.
+	HTTPMethod = stringTagName("http.method")
+
+	// HTTPStatusCode is the numeric HTTP status code (200, 404, etc) of the
+	// HTTP response.
+	HTTPStatusCode = uint16TagName("http.status_code")
+
+	//////////////////////////////////////////////////////////////////////
+	// Error Tag
+	//////////////////////////////////////////////////////////////////////
+
+	// Error indicates that operation represented by the span resulted in an error.
+	Error = boolTagName("error")
+)
+
+// ---
+
+// SpanKindEnum represents common span types
+type SpanKindEnum string
+
+type spanKindTagName string
+
+// Set adds a string tag to the `span`
+func (tag spanKindTagName) Set(span opentracing.Span, value SpanKindEnum) {
+	span.SetTag(string(tag), value)
+}
+
+type rpcServerOption struct {
+	clientContext opentracing.SpanContext
+}
+
+func (r rpcServerOption) Apply(o *opentracing.StartSpanOptions) {
+	if r.clientContext != nil {
+		opentracing.ChildOf(r.clientContext).Apply(o)
+	}
+	SpanKindRPCServer.Apply(o)
+}
+
+// RPCServerOption returns a StartSpanOption appropriate for an RPC server span
+// with `client` representing the metadata for the remote peer Span if available.
+// In case client == nil, due to the client not being instrumented, this RPC
+// server span will be a root span.
+func RPCServerOption(client opentracing.SpanContext) opentracing.StartSpanOption {
+	return rpcServerOption{client}
+}
+
+// ---
+
+type stringTagName string
+
+// Set adds a string tag to the `span`
+func (tag stringTagName) Set(span opentracing.Span, value string) {
+	span.SetTag(string(tag), value)
+}
+
+// ---
+
+type uint32TagName string
+
+// Set adds a uint32 tag to the `span`
+func (tag uint32TagName) Set(span opentracing.Span, value uint32) {
+	span.SetTag(string(tag), value)
+}
+
+// ---
+
+type uint16TagName string
+
+// Set adds a uint16 tag to the `span`
+func (tag uint16TagName) Set(span opentracing.Span, value uint16) {
+	span.SetTag(string(tag), value)
+}
+
+// ---
+
+type boolTagName string
+
+// Add adds a bool tag to the `span`
+func (tag boolTagName) Set(span opentracing.Span, value bool) {
+	span.SetTag(string(tag), value)
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/globaltracer.go b/vendor/github.com/opentracing/opentracing-go/globaltracer.go
new file mode 100644
index 000000000..2df34c9b1
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/globaltracer.go
@@ -0,0 +1,27 @@
+package opentracing
+
+var (
+	globalTracer Tracer = NoopTracer{}
+)
+
+// InitGlobalTracer sets the [singleton] opentracing.Tracer returned by
+// GlobalTracer(). Those who use GlobalTracer (rather than directly manage an
+// opentracing.Tracer instance) should call InitGlobalTracer as early as
+// possible in main(), prior to calling the `StartSpan` global func below.
+// Prior to calling `InitGlobalTracer`, any Spans started via the `StartSpan`
+// (etc) globals are noops.
+func InitGlobalTracer(tracer Tracer) {
+	globalTracer = tracer
+}
+
+// GlobalTracer returns the global singleton `Tracer` implementation.
+// Before `InitGlobalTracer()` is called, the `GlobalTracer()` is a noop
+// implementation that drops all data handed to it.
+func GlobalTracer() Tracer {
+	return globalTracer
+}
+
+// StartSpan defers to `Tracer.StartSpan`. See `GlobalTracer()`.
+func StartSpan(operationName string, opts ...StartSpanOption) Span {
+	return globalTracer.StartSpan(operationName, opts...)
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/gocontext.go b/vendor/github.com/opentracing/opentracing-go/gocontext.go
new file mode 100644
index 000000000..222a65202
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/gocontext.go
@@ -0,0 +1,57 @@
+package opentracing
+
+import "golang.org/x/net/context"
+
+type contextKey struct{}
+
+var activeSpanKey = contextKey{}
+
+// ContextWithSpan returns a new `context.Context` that holds a reference to
+// `span`'s SpanContext.
+func ContextWithSpan(ctx context.Context, span Span) context.Context {
+	return context.WithValue(ctx, activeSpanKey, span)
+}
+
+// SpanFromContext returns the `Span` previously associated with `ctx`, or
+// `nil` if no such `Span` could be found.
+//
+// NOTE: context.Context != SpanContext: the former is Go's intra-process
+// context propagation mechanism, and the latter houses OpenTracing's per-Span
+// identity and baggage information.
+func SpanFromContext(ctx context.Context) Span {
+	val := ctx.Value(activeSpanKey)
+	if sp, ok := val.(Span); ok {
+		return sp
+	}
+	return nil
+}
+
+// StartSpanFromContext starts and returns a Span with `operationName`, using
+// any Span found within `ctx` as a ChildOfRef. If no such parent could be
+// found, StartSpanFromContext creates a root (parentless) Span.
+//
+// The second return value is a context.Context object built around the
+// returned Span.
+//
+// Example usage:
+//
+//    SomeFunction(ctx context.Context, ...) {
+//        sp, ctx := opentracing.StartSpanFromContext(ctx, "SomeFunction")
+//        defer sp.Finish()
+//        ...
+//    }
+func StartSpanFromContext(ctx context.Context, operationName string, opts ...StartSpanOption) (Span, context.Context) {
+	return startSpanFromContextWithTracer(ctx, GlobalTracer(), operationName, opts...)
+}
+
+// startSpanFromContextWithTracer is factored out for testing purposes.
+func startSpanFromContextWithTracer(ctx context.Context, tracer Tracer, operationName string, opts ...StartSpanOption) (Span, context.Context) {
+	var span Span
+	if parentSpan := SpanFromContext(ctx); parentSpan != nil {
+		opts = append(opts, ChildOf(parentSpan.Context()))
+		span = tracer.StartSpan(operationName, opts...)
+	} else {
+		span = tracer.StartSpan(operationName, opts...)
+	}
+	return span, ContextWithSpan(ctx, span)
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/log/field.go b/vendor/github.com/opentracing/opentracing-go/log/field.go
new file mode 100644
index 000000000..5bc47b644
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/log/field.go
@@ -0,0 +1,241 @@
+package log
+
+import (
+	"fmt"
+	"math"
+)
+
+type fieldType int
+
+const (
+	stringType fieldType = iota
+	boolType
+	intType
+	int32Type
+	uint32Type
+	int64Type
+	uint64Type
+	float32Type
+	float64Type
+	errorType
+	objectType
+	lazyLoggerType
+)
+
+// Field instances are constructed via LogBool, LogString, and so on.
+// Tracing implementations may then handle them via the Field.Marshal
+// method.
+//
+// "heavily influenced by" (i.e., partially stolen from)
+// https://github.com/uber-go/zap
+type Field struct {
+	key          string
+	fieldType    fieldType
+	numericVal   int64
+	stringVal    string
+	interfaceVal interface{}
+}
+
+// String adds a string-valued key:value pair to a Span.LogFields() record
+func String(key, val string) Field {
+	return Field{
+		key:       key,
+		fieldType: stringType,
+		stringVal: val,
+	}
+}
+
+// Bool adds a bool-valued key:value pair to a Span.LogFields() record
+func Bool(key string, val bool) Field {
+	var numericVal int64
+	if val {
+		numericVal = 1
+	}
+	return Field{
+		key:        key,
+		fieldType:  boolType,
+		numericVal: numericVal,
+	}
+}
+
+// Int adds an int-valued key:value pair to a Span.LogFields() record
+func Int(key string, val int) Field {
+	return Field{
+		key:        key,
+		fieldType:  intType,
+		numericVal: int64(val),
+	}
+}
+
+// Int32 adds an int32-valued key:value pair to a Span.LogFields() record
+func Int32(key string, val int32) Field {
+	return Field{
+		key:        key,
+		fieldType:  int32Type,
+		numericVal: int64(val),
+	}
+}
+
+// Int64 adds an int64-valued key:value pair to a Span.LogFields() record
+func Int64(key string, val int64) Field {
+	return Field{
+		key:        key,
+		fieldType:  int64Type,
+		numericVal: val,
+	}
+}
+
+// Uint32 adds a uint32-valued key:value pair to a Span.LogFields() record
+func Uint32(key string, val uint32) Field {
+	return Field{
+		key:        key,
+		fieldType:  uint32Type,
+		numericVal: int64(val),
+	}
+}
+
+// Uint64 adds a uint64-valued key:value pair to a Span.LogFields() record
+func Uint64(key string, val uint64) Field {
+	return Field{
+		key:        key,
+		fieldType:  uint64Type,
+		numericVal: int64(val),
+	}
+}
+
+// Float32 adds a float32-valued key:value pair to a Span.LogFields() record
+func Float32(key string, val float32) Field {
+	return Field{
+		key:        key,
+		fieldType:  float32Type,
+		numericVal: int64(math.Float32bits(val)),
+	}
+}
+
+// Float64 adds a float64-valued key:value pair to a Span.LogFields() record
+func Float64(key string, val float64) Field {
+	return Field{
+		key:        key,
+		fieldType:  float64Type,
+		numericVal: int64(math.Float64bits(val)),
+	}
+}
+
+// Error adds an error with the key "error" to a Span.LogFields() record
+func Error(err error) Field {
+	return Field{
+		key:          "error",
+		fieldType:    errorType,
+		interfaceVal: err,
+	}
+}
+
+// Object adds an object-valued key:value pair to a Span.LogFields() record
+func Object(key string, obj interface{}) Field {
+	return Field{
+		key:          key,
+		fieldType:    objectType,
+		interfaceVal: obj,
+	}
+}
+
+// LazyLogger allows for user-defined, late-bound logging of arbitrary data
+type LazyLogger func(fv Encoder)
+
+// Lazy adds a LazyLogger to a Span.LogFields() record; the tracing
+// implementation will call the LazyLogger function at an indefinite time in
+// the future (after Lazy() returns).
+func Lazy(ll LazyLogger) Field {
+	return Field{
+		fieldType:    lazyLoggerType,
+		interfaceVal: ll,
+	}
+}
+
+// Encoder allows access to the contents of a Field (via a call to
+// Field.Marshal).
+//
+// Tracer implementations typically provide an implementation of Encoder;
+// OpenTracing callers typically do not need to concern themselves with it.
+type Encoder interface {
+	EmitString(key, value string)
+	EmitBool(key string, value bool)
+	EmitInt(key string, value int)
+	EmitInt32(key string, value int32)
+	EmitInt64(key string, value int64)
+	EmitUint32(key string, value uint32)
+	EmitUint64(key string, value uint64)
+	EmitFloat32(key string, value float32)
+	EmitFloat64(key string, value float64)
+	EmitObject(key string, value interface{})
+	EmitLazyLogger(value LazyLogger)
+}
+
+// Marshal passes a Field instance through to the appropriate
+// field-type-specific method of an Encoder.
+func (lf Field) Marshal(visitor Encoder) {
+	switch lf.fieldType {
+	case stringType:
+		visitor.EmitString(lf.key, lf.stringVal)
+	case boolType:
+		visitor.EmitBool(lf.key, lf.numericVal != 0)
+	case intType:
+		visitor.EmitInt(lf.key, int(lf.numericVal))
+	case int32Type:
+		visitor.EmitInt32(lf.key, int32(lf.numericVal))
+	case int64Type:
+		visitor.EmitInt64(lf.key, int64(lf.numericVal))
+	case uint32Type:
+		visitor.EmitUint32(lf.key, uint32(lf.numericVal))
+	case uint64Type:
+		visitor.EmitUint64(lf.key, uint64(lf.numericVal))
+	case float32Type:
+		visitor.EmitFloat32(lf.key, math.Float32frombits(uint32(lf.numericVal)))
+	case float64Type:
+		visitor.EmitFloat64(lf.key, math.Float64frombits(uint64(lf.numericVal)))
+	case errorType:
+		visitor.EmitString(lf.key, lf.interfaceVal.(error).Error())
+	case objectType:
+		visitor.EmitObject(lf.key, lf.interfaceVal)
+	case lazyLoggerType:
+		visitor.EmitLazyLogger(lf.interfaceVal.(LazyLogger))
+	}
+}
+
+// Key returns the field's key.
+func (lf Field) Key() string {
+	return lf.key
+}
+
+// Value returns the field's value as interface{}.
+func (lf Field) Value() interface{} {
+	switch lf.fieldType {
+	case stringType:
+		return lf.stringVal
+	case boolType:
+		return lf.numericVal != 0
+	case intType:
+		return int(lf.numericVal)
+	case int32Type:
+		return int32(lf.numericVal)
+	case int64Type:
+		return int64(lf.numericVal)
+	case uint32Type:
+		return uint32(lf.numericVal)
+	case uint64Type:
+		return uint64(lf.numericVal)
+	case float32Type:
+		return math.Float32frombits(uint32(lf.numericVal))
+	case float64Type:
+		return math.Float64frombits(uint64(lf.numericVal))
+	case errorType, objectType, lazyLoggerType:
+		return lf.interfaceVal
+	default:
+		return nil
+	}
+}
+
+// String returns a string representation of the key and value.
+func (lf Field) String() string {
+	return fmt.Sprint(lf.key, ":", lf.Value())
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/log/util.go b/vendor/github.com/opentracing/opentracing-go/log/util.go
new file mode 100644
index 000000000..3832feb5c
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/log/util.go
@@ -0,0 +1,54 @@
+package log
+
+import "fmt"
+
+// InterleavedKVToFields converts keyValues a la Span.LogKV() to a Field slice
+// a la Span.LogFields().
+func InterleavedKVToFields(keyValues ...interface{}) ([]Field, error) {
+	if len(keyValues)%2 != 0 {
+		return nil, fmt.Errorf("non-even keyValues len: %d", len(keyValues))
+	}
+	fields := make([]Field, len(keyValues)/2)
+	for i := 0; i*2 < len(keyValues); i++ {
+		key, ok := keyValues[i*2].(string)
+		if !ok {
+			return nil, fmt.Errorf(
+				"non-string key (pair #%d): %T",
+				i, keyValues[i*2])
+		}
+		switch typedVal := keyValues[i*2+1].(type) {
+		case bool:
+			fields[i] = Bool(key, typedVal)
+		case string:
+			fields[i] = String(key, typedVal)
+		case int:
+			fields[i] = Int(key, typedVal)
+		case int8:
+			fields[i] = Int32(key, int32(typedVal))
+		case int16:
+			fields[i] = Int32(key, int32(typedVal))
+		case int32:
+			fields[i] = Int32(key, typedVal)
+		case int64:
+			fields[i] = Int64(key, typedVal)
+		case uint:
+			fields[i] = Uint64(key, uint64(typedVal))
+		case uint64:
+			fields[i] = Uint64(key, typedVal)
+		case uint8:
+			fields[i] = Uint32(key, uint32(typedVal))
+		case uint16:
+			fields[i] = Uint32(key, uint32(typedVal))
+		case uint32:
+			fields[i] = Uint32(key, typedVal)
+		case float32:
+			fields[i] = Float32(key, typedVal)
+		case float64:
+			fields[i] = Float64(key, typedVal)
+		default:
+			// When in doubt, coerce to a string
+			fields[i] = String(key, fmt.Sprint(typedVal))
+		}
+	}
+	return fields, nil
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/mocktracer/mocklogrecord.go b/vendor/github.com/opentracing/opentracing-go/mocktracer/mocklogrecord.go
new file mode 100644
index 000000000..2ce96d9d3
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/mocktracer/mocklogrecord.go
@@ -0,0 +1,105 @@
+package mocktracer
+
+import (
+	"fmt"
+	"reflect"
+	"time"
+
+	"github.com/opentracing/opentracing-go/log"
+)
+
+// MockLogRecord represents data logged to a Span via Span.LogFields or
+// Span.LogKV.
+type MockLogRecord struct {
+	Timestamp time.Time
+	Fields    []MockKeyValue
+}
+
+// MockKeyValue represents a single key:value pair.
+type MockKeyValue struct {
+	Key string
+
+	// All MockLogRecord values are coerced to strings via fmt.Sprint(), though
+	// we retain their type separately.
+	ValueKind   reflect.Kind
+	ValueString string
+}
+
+// EmitString belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitString(key, value string) {
+	m.Key = key
+	m.ValueKind = reflect.TypeOf(value).Kind()
+	m.ValueString = fmt.Sprint(value)
+}
+
+// EmitBool belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitBool(key string, value bool) {
+	m.Key = key
+	m.ValueKind = reflect.TypeOf(value).Kind()
+	m.ValueString = fmt.Sprint(value)
+}
+
+// EmitInt belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitInt(key string, value int) {
+	m.Key = key
+	m.ValueKind = reflect.TypeOf(value).Kind()
+	m.ValueString = fmt.Sprint(value)
+}
+
+// EmitInt32 belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitInt32(key string, value int32) {
+	m.Key = key
+	m.ValueKind = reflect.TypeOf(value).Kind()
+	m.ValueString = fmt.Sprint(value)
+}
+
+// EmitInt64 belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitInt64(key string, value int64) {
+	m.Key = key
+	m.ValueKind = reflect.TypeOf(value).Kind()
+	m.ValueString = fmt.Sprint(value)
+}
+
+// EmitUint32 belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitUint32(key string, value uint32) {
+	m.Key = key
+	m.ValueKind = reflect.TypeOf(value).Kind()
+	m.ValueString = fmt.Sprint(value)
+}
+
+// EmitUint64 belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitUint64(key string, value uint64) {
+	m.Key = key
+	m.ValueKind = reflect.TypeOf(value).Kind()
+	m.ValueString = fmt.Sprint(value)
+}
+
+// EmitFloat32 belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitFloat32(key string, value float32) {
+	m.Key = key
+	m.ValueKind = reflect.TypeOf(value).Kind()
+	m.ValueString = fmt.Sprint(value)
+}
+
+// EmitFloat64 belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitFloat64(key string, value float64) {
+	m.Key = key
+	m.ValueKind = reflect.TypeOf(value).Kind()
+	m.ValueString = fmt.Sprint(value)
+}
+
+// EmitObject belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitObject(key string, value interface{}) {
+	m.Key = key
+	m.ValueKind = reflect.TypeOf(value).Kind()
+	m.ValueString = fmt.Sprint(value)
+}
+
+// EmitLazyLogger belongs to the log.Encoder interface
+func (m *MockKeyValue) EmitLazyLogger(value log.LazyLogger) {
+	var meta MockKeyValue
+	value(&meta)
+	m.Key = meta.Key
+	m.ValueKind = meta.ValueKind
+	m.ValueString = meta.ValueString
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/mocktracer/mockspan.go b/vendor/github.com/opentracing/opentracing-go/mocktracer/mockspan.go
new file mode 100644
index 000000000..5ca711485
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/mocktracer/mockspan.go
@@ -0,0 +1,283 @@
+package mocktracer
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/opentracing/opentracing-go"
+	"github.com/opentracing/opentracing-go/ext"
+	"github.com/opentracing/opentracing-go/log"
+)
+
+// MockSpanContext is an opentracing.SpanContext implementation.
+//
+// It is entirely unsuitable for production use, but appropriate for tests
+// that want to verify tracing behavior in other frameworks/applications.
+//
+// By default all spans have Sampled=true flag, unless {"sampling.priority": 0}
+// tag is set.
+type MockSpanContext struct {
+	TraceID int
+	SpanID  int
+	Sampled bool
+	Baggage map[string]string
+}
+
+var mockIDSource = uint32(42)
+
+func nextMockID() int {
+	atomic.AddUint32(&mockIDSource, 1)
+	return int(atomic.LoadUint32(&mockIDSource))
+}
+
+// ForeachBaggageItem belongs to the SpanContext interface
+func (c MockSpanContext) ForeachBaggageItem(handler func(k, v string) bool) {
+	for k, v := range c.Baggage {
+		if !handler(k, v) {
+			break
+		}
+	}
+}
+
+// WithBaggageItem creates a new context with an extra baggage item.
+func (c MockSpanContext) WithBaggageItem(key, value string) MockSpanContext {
+	var newBaggage map[string]string
+	if c.Baggage == nil {
+		newBaggage = map[string]string{key: value}
+	} else {
+		newBaggage = make(map[string]string, len(c.Baggage)+1)
+		for k, v := range c.Baggage {
+			newBaggage[k] = v
+		}
+		newBaggage[key] = value
+	}
+	// Use positional parameters so the compiler will help catch new fields.
+	return MockSpanContext{c.TraceID, c.SpanID, c.Sampled, newBaggage}
+}
+
+// MockSpan is an opentracing.Span implementation that exports its internal
+// state for testing purposes.
+type MockSpan struct {
+	sync.RWMutex
+
+	ParentID int
+
+	OperationName string
+	StartTime     time.Time
+	FinishTime    time.Time
+
+	// All of the below are protected by the embedded RWMutex.
+	SpanContext MockSpanContext
+	tags        map[string]interface{}
+	logs        []MockLogRecord
+	tracer      *MockTracer
+}
+
+func newMockSpan(t *MockTracer, name string, opts opentracing.StartSpanOptions) *MockSpan {
+	tags := opts.Tags
+	if tags == nil {
+		tags = map[string]interface{}{}
+	}
+	traceID := nextMockID()
+	parentID := int(0)
+	var baggage map[string]string
+	sampled := true
+	if len(opts.References) > 0 {
+		traceID = opts.References[0].ReferencedContext.(MockSpanContext).TraceID
+		parentID = opts.References[0].ReferencedContext.(MockSpanContext).SpanID
+		sampled = opts.References[0].ReferencedContext.(MockSpanContext).Sampled
+		baggage = opts.References[0].ReferencedContext.(MockSpanContext).Baggage
+	}
+	spanContext := MockSpanContext{traceID, nextMockID(), sampled, baggage}
+	startTime := opts.StartTime
+	if startTime.IsZero() {
+		startTime = time.Now()
+	}
+	return &MockSpan{
+		ParentID:      parentID,
+		OperationName: name,
+		StartTime:     startTime,
+		tags:          tags,
+		logs:          []MockLogRecord{},
+		SpanContext:   spanContext,
+
+		tracer: t,
+	}
+}
+
+// Tags returns a copy of tags accumulated by the span so far
+func (s *MockSpan) Tags() map[string]interface{} {
+	s.RLock()
+	defer s.RUnlock()
+	tags := make(map[string]interface{})
+	for k, v := range s.tags {
+		tags[k] = v
+	}
+	return tags
+}
+
+// Tag returns a single tag
+func (s *MockSpan) Tag(k string) interface{} {
+	s.RLock()
+	defer s.RUnlock()
+	return s.tags[k]
+}
+
+// Logs returns a copy of logs accumulated in the span so far
+func (s *MockSpan) Logs() []MockLogRecord {
+	s.RLock()
+	defer s.RUnlock()
+	logs := make([]MockLogRecord, len(s.logs))
+	copy(logs, s.logs)
+	return logs
+}
+
+// Context belongs to the Span interface
+func (s *MockSpan) Context() opentracing.SpanContext {
+	return s.SpanContext
+}
+
+// SetTag belongs to the Span interface
+func (s *MockSpan) SetTag(key string, value interface{}) opentracing.Span {
+	s.Lock()
+	defer s.Unlock()
+	if key == string(ext.SamplingPriority) {
+		if v, ok := value.(uint16); ok {
+			s.SpanContext.Sampled = v > 0
+			return s
+		}
+		if v, ok := value.(int); ok {
+			s.SpanContext.Sampled = v > 0
+			return s
+		}
+	}
+	s.tags[key] = value
+	return s
+}
+
+// SetBaggageItem belongs to the Span interface
+func (s *MockSpan) SetBaggageItem(key, val string) opentracing.Span {
+	s.Lock()
+	defer s.Unlock()
+	s.SpanContext = s.SpanContext.WithBaggageItem(key, val)
+	return s
+}
+
+// BaggageItem belongs to the Span interface
+func (s *MockSpan) BaggageItem(key string) string {
+	s.RLock()
+	defer s.RUnlock()
+	return s.SpanContext.Baggage[key]
+}
+
+// Finish belongs to the Span interface
+func (s *MockSpan) Finish() {
+	s.Lock()
+	s.FinishTime = time.Now()
+	s.Unlock()
+	s.tracer.recordSpan(s)
+}
+
+// FinishWithOptions belongs to the Span interface
+func (s *MockSpan) FinishWithOptions(opts opentracing.FinishOptions) {
+	s.Lock()
+	s.FinishTime = opts.FinishTime
+	s.Unlock()
+
+	// Handle any late-bound LogRecords.
+	for _, lr := range opts.LogRecords {
+		s.logFieldsWithTimestamp(lr.Timestamp, lr.Fields...)
+	}
+	// Handle (deprecated) BulkLogData.
+	for _, ld := range opts.BulkLogData {
+		if ld.Payload != nil {
+			s.logFieldsWithTimestamp(
+				ld.Timestamp,
+				log.String("event", ld.Event),
+				log.Object("payload", ld.Payload))
+		} else {
+			s.logFieldsWithTimestamp(
+				ld.Timestamp,
+				log.String("event", ld.Event))
+		}
+	}
+
+	s.tracer.recordSpan(s)
+}
+
+// String allows printing span for debugging
+func (s *MockSpan) String() string {
+	return fmt.Sprintf(
+		"traceId=%d, spanId=%d, parentId=%d, sampled=%t, name=%s",
+		s.SpanContext.TraceID, s.SpanContext.SpanID, s.ParentID,
+		s.SpanContext.Sampled, s.OperationName)
+}
+
+// LogFields belongs to the Span interface
+func (s *MockSpan) LogFields(fields ...log.Field) {
+	s.logFieldsWithTimestamp(time.Now(), fields...)
+}
+
+// The caller MUST NOT hold s.Lock
+func (s *MockSpan) logFieldsWithTimestamp(ts time.Time, fields ...log.Field) {
+	lr := MockLogRecord{
+		Timestamp: ts,
+		Fields:    make([]MockKeyValue, len(fields)),
+	}
+	for i, f := range fields {
+		outField := &(lr.Fields[i])
+		f.Marshal(outField)
+	}
+
+	s.Lock()
+	defer s.Unlock()
+	s.logs = append(s.logs, lr)
+}
+
+// LogKV belongs to the Span interface.
+//
+// This implementations coerces all "values" to strings, though that is not
+// something all implementations need to do. Indeed, a motivated person can and
+// probably should have this do a typed switch on the values.
+func (s *MockSpan) LogKV(keyValues ...interface{}) {
+	if len(keyValues)%2 != 0 {
+		s.LogFields(log.Error(fmt.Errorf("Non-even keyValues len: %v", len(keyValues))))
+		return
+	}
+	fields, err := log.InterleavedKVToFields(keyValues...)
+	if err != nil {
+		s.LogFields(log.Error(err), log.String("function", "LogKV"))
+		return
+	}
+	s.LogFields(fields...)
+}
+
+// LogEvent belongs to the Span interface
+func (s *MockSpan) LogEvent(event string) {
+	s.LogFields(log.String("event", event))
+}
+
+// LogEventWithPayload belongs to the Span interface
+func (s *MockSpan) LogEventWithPayload(event string, payload interface{}) {
+	s.LogFields(log.String("event", event), log.Object("payload", payload))
+}
+
+// Log belongs to the Span interface
+func (s *MockSpan) Log(data opentracing.LogData) {
+	panic("MockSpan.Log() no longer supported")
+}
+
+// SetOperationName belongs to the Span interface
+func (s *MockSpan) SetOperationName(operationName string) opentracing.Span {
+	s.Lock()
+	defer s.Unlock()
+	s.OperationName = operationName
+	return s
+}
+
+// Tracer belongs to the Span interface
+func (s *MockSpan) Tracer() opentracing.Tracer {
+	return s.tracer
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/mocktracer/mocktracer.go b/vendor/github.com/opentracing/opentracing-go/mocktracer/mocktracer.go
new file mode 100644
index 000000000..a74c1458a
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/mocktracer/mocktracer.go
@@ -0,0 +1,105 @@
+package mocktracer
+
+import (
+	"sync"
+
+	"github.com/opentracing/opentracing-go"
+)
+
+// New returns a MockTracer opentracing.Tracer implementation that's intended
+// to facilitate tests of OpenTracing instrumentation.
+func New() *MockTracer {
+	t := &MockTracer{
+		finishedSpans: []*MockSpan{},
+		injectors:     make(map[interface{}]Injector),
+		extractors:    make(map[interface{}]Extractor),
+	}
+
+	// register default injectors/extractors
+	textPropagator := new(TextMapPropagator)
+	t.RegisterInjector(opentracing.TextMap, textPropagator)
+	t.RegisterExtractor(opentracing.TextMap, textPropagator)
+
+	httpPropagator := &TextMapPropagator{HTTPHeaders: true}
+	t.RegisterInjector(opentracing.HTTPHeaders, httpPropagator)
+	t.RegisterExtractor(opentracing.HTTPHeaders, httpPropagator)
+
+	return t
+}
+
+// MockTracer is only intended for testing OpenTracing instrumentation.
+//
+// It is entirely unsuitable for production use, but appropriate for tests
+// that want to verify tracing behavior in other frameworks/applications.
+type MockTracer struct {
+	sync.RWMutex
+	finishedSpans []*MockSpan
+	injectors     map[interface{}]Injector
+	extractors    map[interface{}]Extractor
+}
+
+// FinishedSpans returns all spans that have been Finish()'ed since the
+// MockTracer was constructed or since the last call to its Reset() method.
+func (t *MockTracer) FinishedSpans() []*MockSpan {
+	t.RLock()
+	defer t.RUnlock()
+	spans := make([]*MockSpan, len(t.finishedSpans))
+	copy(spans, t.finishedSpans)
+	return spans
+}
+
+// Reset clears the internally accumulated finished spans. Note that any
+// extant MockSpans will still append to finishedSpans when they Finish(),
+// even after a call to Reset().
+func (t *MockTracer) Reset() {
+	t.Lock()
+	defer t.Unlock()
+	t.finishedSpans = []*MockSpan{}
+}
+
+// StartSpan belongs to the Tracer interface.
+func (t *MockTracer) StartSpan(operationName string, opts ...opentracing.StartSpanOption) opentracing.Span {
+	sso := opentracing.StartSpanOptions{}
+	for _, o := range opts {
+		o.Apply(&sso)
+	}
+	return newMockSpan(t, operationName, sso)
+}
+
+// RegisterInjector registers injector for given format
+func (t *MockTracer) RegisterInjector(format interface{}, injector Injector) {
+	t.injectors[format] = injector
+}
+
+// RegisterExtractor registers extractor for given format
+func (t *MockTracer) RegisterExtractor(format interface{}, extractor Extractor) {
+	t.extractors[format] = extractor
+}
+
+// Inject belongs to the Tracer interface.
+func (t *MockTracer) Inject(sm opentracing.SpanContext, format interface{}, carrier interface{}) error {
+	spanContext, ok := sm.(MockSpanContext)
+	if !ok {
+		return opentracing.ErrInvalidCarrier
+	}
+	injector, ok := t.injectors[format]
+	if !ok {
+		return opentracing.ErrUnsupportedFormat
+	}
+	return injector.Inject(spanContext, carrier)
+}
+
+// Extract belongs to the Tracer interface.
+func (t *MockTracer) Extract(format interface{}, carrier interface{}) (opentracing.SpanContext, error) {
+	extractor, ok := t.extractors[format]
+	if !ok {
+		return nil, opentracing.ErrUnsupportedFormat
+	}
+	return extractor.Extract(carrier)
+}
+
+func (t *MockTracer) recordSpan(span *MockSpan) {
+	t.Lock()
+	defer t.Unlock()
+	t.finishedSpans = append(t.finishedSpans, span)
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/mocktracer/propagation.go b/vendor/github.com/opentracing/opentracing-go/mocktracer/propagation.go
new file mode 100644
index 000000000..8364f1d18
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/mocktracer/propagation.go
@@ -0,0 +1,120 @@
+package mocktracer
+
+import (
+	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"github.com/opentracing/opentracing-go"
+)
+
+const mockTextMapIdsPrefix = "mockpfx-ids-"
+const mockTextMapBaggagePrefix = "mockpfx-baggage-"
+
+var emptyContext = MockSpanContext{}
+
+// Injector is responsible for injecting SpanContext instances in a manner suitable
+// for propagation via a format-specific "carrier" object. Typically the
+// injection will take place across an RPC boundary, but message queues and
+// other IPC mechanisms are also reasonable places to use an Injector.
+type Injector interface {
+	// Inject takes `SpanContext` and injects it into `carrier`. The actual type
+	// of `carrier` depends on the `format` passed to `Tracer.Inject()`.
+	//
+	// Implementations may return opentracing.ErrInvalidCarrier or any other
+	// implementation-specific error if injection fails.
+	Inject(ctx MockSpanContext, carrier interface{}) error
+}
+
+// Extractor is responsible for extracting SpanContext instances from a
+// format-specific "carrier" object. Typically the extraction will take place
+// on the server side of an RPC boundary, but message queues and other IPC
+// mechanisms are also reasonable places to use an Extractor.
+type Extractor interface {
+	// Extract decodes a SpanContext instance from the given `carrier`,
+	// or (nil, opentracing.ErrSpanContextNotFound) if no context could
+	// be found in the `carrier`.
+	Extract(carrier interface{}) (MockSpanContext, error)
+}
+
+// TextMapPropagator implements Injector/Extractor for TextMap and HTTPHeaders formats.
+type TextMapPropagator struct {
+	HTTPHeaders bool
+}
+
+// Inject implements the Injector interface
+func (t *TextMapPropagator) Inject(spanContext MockSpanContext, carrier interface{}) error {
+	writer, ok := carrier.(opentracing.TextMapWriter)
+	if !ok {
+		return opentracing.ErrInvalidCarrier
+	}
+	// Ids:
+	writer.Set(mockTextMapIdsPrefix+"traceid", strconv.Itoa(spanContext.TraceID))
+	writer.Set(mockTextMapIdsPrefix+"spanid", strconv.Itoa(spanContext.SpanID))
+	writer.Set(mockTextMapIdsPrefix+"sampled", fmt.Sprint(spanContext.Sampled))
+	// Baggage:
+	for baggageKey, baggageVal := range spanContext.Baggage {
+		safeVal := baggageVal
+		if t.HTTPHeaders {
+			safeVal = url.QueryEscape(baggageVal)
+		}
+		writer.Set(mockTextMapBaggagePrefix+baggageKey, safeVal)
+	}
+	return nil
+}
+
+// Extract implements the Extractor interface
+func (t *TextMapPropagator) Extract(carrier interface{}) (MockSpanContext, error) {
+	reader, ok := carrier.(opentracing.TextMapReader)
+	if !ok {
+		return emptyContext, opentracing.ErrInvalidCarrier
+	}
+	rval := MockSpanContext{0, 0, true, nil}
+	err := reader.ForeachKey(func(key, val string) error {
+		lowerKey := strings.ToLower(key)
+		switch {
+		case lowerKey == mockTextMapIdsPrefix+"traceid":
+			// Ids:
+			i, err := strconv.Atoi(val)
+			if err != nil {
+				return err
+			}
+			rval.TraceID = i
+		case lowerKey == mockTextMapIdsPrefix+"spanid":
+			// Ids:
+			i, err := strconv.Atoi(val)
+			if err != nil {
+				return err
+			}
+			rval.SpanID = i
+		case lowerKey == mockTextMapIdsPrefix+"sampled":
+			b, err := strconv.ParseBool(val)
+			if err != nil {
+				return err
+			}
+			rval.Sampled = b
+		case strings.HasPrefix(lowerKey, mockTextMapBaggagePrefix):
+			// Baggage:
+			if rval.Baggage == nil {
+				rval.Baggage = make(map[string]string)
+			}
+			safeVal := val
+			if t.HTTPHeaders {
+				// unescape errors are ignored, nothing can be done
+				if rawVal, err := url.QueryUnescape(val); err == nil {
+					safeVal = rawVal
+				}
+			}
+			rval.Baggage[lowerKey[len(mockTextMapBaggagePrefix):]] = safeVal
+		}
+		return nil
+	})
+	if rval.TraceID == 0 || rval.SpanID == 0 {
+		return emptyContext, opentracing.ErrSpanContextNotFound
+	}
+	if err != nil {
+		return emptyContext, err
+	}
+	return rval, nil
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/noop.go b/vendor/github.com/opentracing/opentracing-go/noop.go
new file mode 100644
index 000000000..bd559dc8d
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/noop.go
@@ -0,0 +1,53 @@
+package opentracing
+
+import "github.com/opentracing/opentracing-go/log"
+
+// A NoopTracer is a trivial implementation of Tracer for which all operations
+// are no-ops.
+type NoopTracer struct{}
+
+type noopSpan struct{}
+type noopSpanContext struct{}
+
+var (
+	defaultNoopSpanContext = noopSpanContext{}
+	defaultNoopSpan        = noopSpan{}
+	defaultNoopTracer      = NoopTracer{}
+)
+
+const (
+	emptyString = ""
+)
+
+// noopSpanContext:
+func (n noopSpanContext) ForeachBaggageItem(handler func(k, v string) bool) {}
+
+// noopSpan:
+func (n noopSpan) Context() SpanContext                                  { return defaultNoopSpanContext }
+func (n noopSpan) SetBaggageItem(key, val string) Span                   { return defaultNoopSpan }
+func (n noopSpan) BaggageItem(key string) string                         { return emptyString }
+func (n noopSpan) SetTag(key string, value interface{}) Span             { return n }
+func (n noopSpan) LogFields(fields ...log.Field)                         {}
+func (n noopSpan) LogKV(keyVals ...interface{})                          {}
+func (n noopSpan) Finish()                                               {}
+func (n noopSpan) FinishWithOptions(opts FinishOptions)                  {}
+func (n noopSpan) SetOperationName(operationName string) Span            { return n }
+func (n noopSpan) Tracer() Tracer                                        { return defaultNoopTracer }
+func (n noopSpan) LogEvent(event string)                                 {}
+func (n noopSpan) LogEventWithPayload(event string, payload interface{}) {}
+func (n noopSpan) Log(data LogData)                                      {}
+
+// StartSpan belongs to the Tracer interface.
+func (n NoopTracer) StartSpan(operationName string, opts ...StartSpanOption) Span {
+	return defaultNoopSpan
+}
+
+// Inject belongs to the Tracer interface.
+func (n NoopTracer) Inject(sp SpanContext, format interface{}, carrier interface{}) error {
+	return nil
+}
+
+// Extract belongs to the Tracer interface.
+func (n NoopTracer) Extract(format interface{}, carrier interface{}) (SpanContext, error) {
+	return nil, ErrSpanContextNotFound
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/propagation.go b/vendor/github.com/opentracing/opentracing-go/propagation.go
new file mode 100644
index 000000000..9583fc53a
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/propagation.go
@@ -0,0 +1,176 @@
+package opentracing
+
+import (
+	"errors"
+	"net/http"
+)
+
+///////////////////////////////////////////////////////////////////////////////
+// CORE PROPAGATION INTERFACES:
+///////////////////////////////////////////////////////////////////////////////
+
+var (
+	// ErrUnsupportedFormat occurs when the `format` passed to Tracer.Inject() or
+	// Tracer.Extract() is not recognized by the Tracer implementation.
+	ErrUnsupportedFormat = errors.New("opentracing: Unknown or unsupported Inject/Extract format")
+
+	// ErrSpanContextNotFound occurs when the `carrier` passed to
+	// Tracer.Extract() is valid and uncorrupted but has insufficient
+	// information to extract a SpanContext.
+	ErrSpanContextNotFound = errors.New("opentracing: SpanContext not found in Extract carrier")
+
+	// ErrInvalidSpanContext errors occur when Tracer.Inject() is asked to
+	// operate on a SpanContext which it is not prepared to handle (for
+	// example, since it was created by a different tracer implementation).
+	ErrInvalidSpanContext = errors.New("opentracing: SpanContext type incompatible with tracer")
+
+	// ErrInvalidCarrier errors occur when Tracer.Inject() or Tracer.Extract()
+	// implementations expect a different type of `carrier` than they are
+	// given.
+	ErrInvalidCarrier = errors.New("opentracing: Invalid Inject/Extract carrier")
+
+	// ErrSpanContextCorrupted occurs when the `carrier` passed to
+	// Tracer.Extract() is of the expected type but is corrupted.
+	ErrSpanContextCorrupted = errors.New("opentracing: SpanContext data corrupted in Extract carrier")
+)
+
+///////////////////////////////////////////////////////////////////////////////
+// BUILTIN PROPAGATION FORMATS:
+///////////////////////////////////////////////////////////////////////////////
+
+// BuiltinFormat is used to demarcate the values within package `opentracing`
+// that are intended for use with the Tracer.Inject() and Tracer.Extract()
+// methods.
+type BuiltinFormat byte
+
+const (
+	// Binary represents SpanContexts as opaque binary data.
+	//
+	// For Tracer.Inject(): the carrier must be an `io.Writer`.
+	//
+	// For Tracer.Extract(): the carrier must be an `io.Reader`.
+	Binary BuiltinFormat = iota
+
+	// TextMap represents SpanContexts as key:value string pairs.
+	//
+	// Unlike HTTPHeaders, the TextMap format does not restrict the key or
+	// value character sets in any way.
+	//
+	// For Tracer.Inject(): the carrier must be a `TextMapWriter`.
+	//
+	// For Tracer.Extract(): the carrier must be a `TextMapReader`.
+	TextMap
+
+	// HTTPHeaders represents SpanContexts as HTTP header string pairs.
+	//
+	// Unlike TextMap, the HTTPHeaders format requires that the keys and values
+	// be valid as HTTP headers as-is (i.e., character casing may be unstable
+	// and special characters are disallowed in keys, values should be
+	// URL-escaped, etc).
+	//
+	// For Tracer.Inject(): the carrier must be a `TextMapWriter`.
+	//
+	// For Tracer.Extract(): the carrier must be a `TextMapReader`.
+	//
+	// See HTTPHeaderCarrier for an implementation of both TextMapWriter
+	// and TextMapReader that defers to an http.Header instance for storage.
+	// For example, Inject():
+	//
+	//    carrier := opentracing.HTTPHeadersCarrier(httpReq.Header)
+	//    err := span.Tracer().Inject(
+	//        span, opentracing.HTTPHeaders, carrier)
+	//
+	// Or Extract():
+	//
+	//    carrier := opentracing.HTTPHeadersCarrier(httpReq.Header)
+	//    span, err := tracer.Extract(
+	//        opentracing.HTTPHeaders, carrier)
+	//
+	HTTPHeaders
+)
+
+// TextMapWriter is the Inject() carrier for the TextMap builtin format. With
+// it, the caller can encode a SpanContext for propagation as entries in a map
+// of unicode strings.
+type TextMapWriter interface {
+	// Set a key:value pair to the carrier. Multiple calls to Set() for the
+	// same key leads to undefined behavior.
+	//
+	// NOTE: The backing store for the TextMapWriter may contain data unrelated
+	// to SpanContext. As such, Inject() and Extract() implementations that
+	// call the TextMapWriter and TextMapReader interfaces must agree on a
+	// prefix or other convention to distinguish their own key:value pairs.
+	Set(key, val string)
+}
+
+// TextMapReader is the Extract() carrier for the TextMap builtin format. With it,
+// the caller can decode a propagated SpanContext as entries in a map of
+// unicode strings.
+type TextMapReader interface {
+	// ForeachKey returns TextMap contents via repeated calls to the `handler`
+	// function. If any call to `handler` returns a non-nil error, ForeachKey
+	// terminates and returns that error.
+	//
+	// NOTE: The backing store for the TextMapReader may contain data unrelated
+	// to SpanContext. As such, Inject() and Extract() implementations that
+	// call the TextMapWriter and TextMapReader interfaces must agree on a
+	// prefix or other convention to distinguish their own key:value pairs.
+	//
+	// The "foreach" callback pattern reduces unnecessary copying in some cases
+	// and also allows implementations to hold locks while the map is read.
+	ForeachKey(handler func(key, val string) error) error
+}
+
+// TextMapCarrier allows the use of regular map[string]string
+// as both TextMapWriter and TextMapReader.
+type TextMapCarrier map[string]string
+
+// ForeachKey conforms to the TextMapReader interface.
+func (c TextMapCarrier) ForeachKey(handler func(key, val string) error) error {
+	for k, v := range c {
+		if err := handler(k, v); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Set implements Set() of opentracing.TextMapWriter
+func (c TextMapCarrier) Set(key, val string) {
+	c[key] = val
+}
+
+// HTTPHeadersCarrier satisfies both TextMapWriter and TextMapReader.
+//
+// Example usage for server side:
+//
+//     carrier := opentracing.HttpHeadersCarrier(httpReq.Header)
+//     spanContext, err := tracer.Extract(opentracing.HttpHeaders, carrier)
+//
+// Example usage for client side:
+//
+//     carrier := opentracing.HTTPHeadersCarrier(httpReq.Header)
+//     err := tracer.Inject(
+//         span.Context(),
+//         opentracing.HttpHeaders,
+//         carrier)
+//
+type HTTPHeadersCarrier http.Header
+
+// Set conforms to the TextMapWriter interface.
+func (c HTTPHeadersCarrier) Set(key, val string) {
+	h := http.Header(c)
+	h.Add(key, val)
+}
+
+// ForeachKey conforms to the TextMapReader interface.
+func (c HTTPHeadersCarrier) ForeachKey(handler func(key, val string) error) error {
+	for k, vals := range c {
+		for _, v := range vals {
+			if err := handler(k, v); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
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 000000000..f6c3234ac
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/span.go
@@ -0,0 +1,185 @@
+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.
+	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.
+	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
+}
diff --git a/vendor/github.com/opentracing/opentracing-go/tracer.go b/vendor/github.com/opentracing/opentracing-go/tracer.go
new file mode 100644
index 000000000..c84c4fdc4
--- /dev/null
+++ b/vendor/github.com/opentracing/opentracing-go/tracer.go
@@ -0,0 +1,305 @@
+package opentracing
+
+import "time"
+
+// Tracer is a simple, thin interface for Span creation and SpanContext
+// propagation.
+type Tracer interface {
+
+	// Create, start, and return a new Span with the given `operationName` and
+	// incorporate the given StartSpanOption `opts`. (Note that `opts` borrows
+	// from the "functional options" pattern, per
+	// http://dave.cheney.net/2014/10/17/functional-options-for-friendly-apis)
+	//
+	// A Span with no SpanReference options (e.g., opentracing.ChildOf() or
+	// opentracing.FollowsFrom()) becomes the root of its own trace.
+	//
+	// Examples:
+	//
+	//     var tracer opentracing.Tracer = ...
+	//
+	//     // The root-span case:
+	//     sp := tracer.StartSpan("GetFeed")
+	//
+	//     // The vanilla child span case:
+	//     sp := tracer.StartSpan(
+	//         "GetFeed",
+	//         opentracing.ChildOf(parentSpan.Context()))
+	//
+	//     // All the bells and whistles:
+	//     sp := tracer.StartSpan(
+	//         "GetFeed",
+	//         opentracing.ChildOf(parentSpan.Context()),
+	//         opentracing.Tag("user_agent", loggedReq.UserAgent),
+	//         opentracing.StartTime(loggedReq.Timestamp),
+	//     )
+	//
+	StartSpan(operationName string, opts ...StartSpanOption) Span
+
+	// Inject() takes the `sm` SpanContext instance and injects it for
+	// propagation within `carrier`. The actual type of `carrier` depends on
+	// the value of `format`.
+	//
+	// OpenTracing defines a common set of `format` values (see BuiltinFormat),
+	// and each has an expected carrier type.
+	//
+	// Other packages may declare their own `format` values, much like the keys
+	// used by `context.Context` (see
+	// https://godoc.org/golang.org/x/net/context#WithValue).
+	//
+	// Example usage (sans error handling):
+	//
+	//     carrier := opentracing.HTTPHeadersCarrier(httpReq.Header)
+	//     err := tracer.Inject(
+	//         span.Context(),
+	//         opentracing.HttpHeaders,
+	//         carrier)
+	//
+	// NOTE: All opentracing.Tracer implementations MUST support all
+	// BuiltinFormats.
+	//
+	// Implementations may return opentracing.ErrUnsupportedFormat if `format`
+	// is not supported by (or not known by) the implementation.
+	//
+	// Implementations may return opentracing.ErrInvalidCarrier or any other
+	// implementation-specific error if the format is supported but injection
+	// fails anyway.
+	//
+	// See Tracer.Extract().
+	Inject(sm SpanContext, format interface{}, carrier interface{}) error
+
+	// Extract() returns a SpanContext instance given `format` and `carrier`.
+	//
+	// OpenTracing defines a common set of `format` values (see BuiltinFormat),
+	// and each has an expected carrier type.
+	//
+	// Other packages may declare their own `format` values, much like the keys
+	// used by `context.Context` (see
+	// https://godoc.org/golang.org/x/net/context#WithValue).
+	//
+	// Example usage (with StartSpan):
+	//
+	//
+	//     carrier := opentracing.HttpHeadersCarrier(httpReq.Header)
+	//     clientContext, err := tracer.Extract(opentracing.HttpHeaders, carrier)
+	//
+	//     // ... assuming the ultimate goal here is to resume the trace with a
+	//     // server-side Span:
+	//     var serverSpan opentracing.Span
+	//     if err == nil {
+	//         span = tracer.StartSpan(
+	//             rpcMethodName, ext.RPCServerOption(clientContext))
+	//     } else {
+	//         span = tracer.StartSpan(rpcMethodName)
+	//     }
+	//
+	//
+	// NOTE: All opentracing.Tracer implementations MUST support all
+	// BuiltinFormats.
+	//
+	// Return values:
+	//  - A successful Extract returns a SpanContext instance and a nil error
+	//  - If there was simply no SpanContext to extract in `carrier`, Extract()
+	//    returns (nil, opentracing.ErrSpanContextNotFound)
+	//  - If `format` is unsupported or unrecognized, Extract() returns (nil,
+	//    opentracing.ErrUnsupportedFormat)
+	//  - If there are more fundamental problems with the `carrier` object,
+	//    Extract() may return opentracing.ErrInvalidCarrier,
+	//    opentracing.ErrSpanContextCorrupted, or implementation-specific
+	//    errors.
+	//
+	// See Tracer.Inject().
+	Extract(format interface{}, carrier interface{}) (SpanContext, error)
+}
+
+// StartSpanOptions allows Tracer.StartSpan() callers and implementors a
+// mechanism to override the start timestamp, specify Span References, and make
+// a single Tag or multiple Tags available at Span start time.
+//
+// StartSpan() callers should look at the StartSpanOption interface and
+// implementations available in this package.
+//
+// Tracer implementations can convert a slice of `StartSpanOption` instances
+// into a `StartSpanOptions` struct like so:
+//
+//     func StartSpan(opName string, opts ...opentracing.StartSpanOption) {
+//         sso := opentracing.StartSpanOptions{}
+//         for _, o := range opts {
+//             o.Apply(&sso)
+//         }
+//         ...
+//     }
+//
+type StartSpanOptions struct {
+	// Zero or more causal references to other Spans (via their SpanContext).
+	// If empty, start a "root" Span (i.e., start a new trace).
+	References []SpanReference
+
+	// StartTime overrides the Span's start time, or implicitly becomes
+	// time.Now() if StartTime.IsZero().
+	StartTime time.Time
+
+	// Tags may have zero or more entries; the restrictions on map values are
+	// identical to those for Span.SetTag(). May be nil.
+	//
+	// If specified, the caller hands off ownership of Tags at
+	// StartSpan() invocation time.
+	Tags map[string]interface{}
+}
+
+// StartSpanOption instances (zero or more) may be passed to Tracer.StartSpan.
+//
+// StartSpanOption borrows from the "functional options" pattern, per
+// http://dave.cheney.net/2014/10/17/functional-options-for-friendly-apis
+type StartSpanOption interface {
+	Apply(*StartSpanOptions)
+}
+
+// SpanReferenceType is an enum type describing different categories of
+// relationships between two Spans. If Span-2 refers to Span-1, the
+// SpanReferenceType describes Span-1 from Span-2's perspective. For example,
+// ChildOfRef means that Span-1 created Span-2.
+//
+// NOTE: Span-1 and Span-2 do *not* necessarily depend on each other for
+// completion; e.g., Span-2 may be part of a background job enqueued by Span-1,
+// or Span-2 may be sitting in a distributed queue behind Span-1.
+type SpanReferenceType int
+
+const (
+	// ChildOfRef refers to a parent Span that caused *and* somehow depends
+	// upon the new child Span. Often (but not always), the parent Span cannot
+	// finish until the child Span does.
+	//
+	// An timing diagram for a ChildOfRef that's blocked on the new Span:
+	//
+	//     [-Parent Span---------]
+	//          [-Child Span----]
+	//
+	// See http://opentracing.io/spec/
+	//
+	// See opentracing.ChildOf()
+	ChildOfRef SpanReferenceType = iota
+
+	// FollowsFromRef refers to a parent Span that does not depend in any way
+	// on the result of the new child Span. For instance, one might use
+	// FollowsFromRefs to describe pipeline stages separated by queues,
+	// or a fire-and-forget cache insert at the tail end of a web request.
+	//
+	// A FollowsFromRef Span is part of the same logical trace as the new Span:
+	// i.e., the new Span is somehow caused by the work of its FollowsFromRef.
+	//
+	// All of the following could be valid timing diagrams for children that
+	// "FollowFrom" a parent.
+	//
+	//     [-Parent Span-]  [-Child Span-]
+	//
+	//
+	//     [-Parent Span--]
+	//      [-Child Span-]
+	//
+	//
+	//     [-Parent Span-]
+	//                 [-Child Span-]
+	//
+	// See http://opentracing.io/spec/
+	//
+	// See opentracing.FollowsFrom()
+	FollowsFromRef
+)
+
+// SpanReference is a StartSpanOption that pairs a SpanReferenceType and a
+// referenced SpanContext. See the SpanReferenceType documentation for
+// supported relationships.  If SpanReference is created with
+// ReferencedContext==nil, it has no effect. Thus it allows for a more concise
+// syntax for starting spans:
+//
+//     sc, _ := tracer.Extract(someFormat, someCarrier)
+//     span := tracer.StartSpan("operation", opentracing.ChildOf(sc))
+//
+// The `ChildOf(sc)` option above will not panic if sc == nil, it will just
+// not add the parent span reference to the options.
+type SpanReference struct {
+	Type              SpanReferenceType
+	ReferencedContext SpanContext
+}
+
+// Apply satisfies the StartSpanOption interface.
+func (r SpanReference) Apply(o *StartSpanOptions) {
+	if r.ReferencedContext != nil {
+		o.References = append(o.References, r)
+	}
+}
+
+// ChildOf returns a StartSpanOption pointing to a dependent parent span.
+// If sc == nil, the option has no effect.
+//
+// See ChildOfRef, SpanReference
+func ChildOf(sc SpanContext) SpanReference {
+	return SpanReference{
+		Type:              ChildOfRef,
+		ReferencedContext: sc,
+	}
+}
+
+// FollowsFrom returns a StartSpanOption pointing to a parent Span that caused
+// the child Span but does not directly depend on its result in any way.
+// If sc == nil, the option has no effect.
+//
+// See FollowsFromRef, SpanReference
+func FollowsFrom(sc SpanContext) SpanReference {
+	return SpanReference{
+		Type:              FollowsFromRef,
+		ReferencedContext: sc,
+	}
+}
+
+// StartTime is a StartSpanOption that sets an explicit start timestamp for the
+// new Span.
+type StartTime time.Time
+
+// Apply satisfies the StartSpanOption interface.
+func (t StartTime) Apply(o *StartSpanOptions) {
+	o.StartTime = time.Time(t)
+}
+
+// Tags are a generic map from an arbitrary string key to an opaque value type.
+// The underlying tracing system is responsible for interpreting and
+// serializing the values.
+type Tags map[string]interface{}
+
+// Apply satisfies the StartSpanOption interface.
+func (t Tags) Apply(o *StartSpanOptions) {
+	if o.Tags == nil {
+		o.Tags = make(map[string]interface{})
+	}
+	for k, v := range t {
+		o.Tags[k] = v
+	}
+}
+
+// Tag may be passed as a StartSpanOption to add a tag to new spans,
+// or its Set method may be used to apply the tag to an existing Span,
+// for example:
+//
+// tracer.StartSpan("opName", Tag{"Key", value})
+//
+//   or
+//
+// Tag{"key", value}.Set(span)
+type Tag struct {
+	Key   string
+	Value interface{}
+}
+
+// Apply satisfies the StartSpanOption interface.
+func (t Tag) Apply(o *StartSpanOptions) {
+	if o.Tags == nil {
+		o.Tags = make(map[string]interface{})
+	}
+	o.Tags[t.Key] = t.Value
+}
+
+// Set applies the tag to an existing Span.
+func (t Tag) Set(s Span) {
+	s.SetTag(t.Key, t.Value)
+}
diff --git a/vendor/manifest b/vendor/manifest
index 47adef686..0ca5f4ca4 100644
--- a/vendor/manifest
+++ b/vendor/manifest
@@ -1116,6 +1116,14 @@
 			"branch": "master",
 			"path": "/libcontainer/utils"
 		},
+		{
+			"importpath": "github.com/opentracing/opentracing-go",
+			"repository": "https://github.com/opentracing/opentracing-go",
+			"vcs": "git",
+			"revision": "902ca977fd85455c364050f985eba376b44315f0",
+			"branch": "master",
+			"notests": true
+		},
 		{
 			"importpath": "github.com/paypal/ionet",
 			"repository": "https://github.com/paypal/ionet",