Add distributed tracing with LabKit

Makefile

@@ -48,15 +48,15 @@ $(TARGET_SETUP):
 
 gitlab-zip-cat:	$(TARGET_SETUP) $(shell find cmd/gitlab-zip-cat/ -name '*.go')
 	$(call message,Building $@)
-	$(GOBUILD) -o $(BUILD_DIR)/$@ $(PKG)/cmd/$@
+	$(GOBUILD) -tags "$(BUILD_TAGS)" -o $(BUILD_DIR)/$@ $(PKG)/cmd/$@
 
 gitlab-zip-metadata:	$(TARGET_SETUP) $(shell find cmd/gitlab-zip-metadata/ -name '*.go')
 	$(call message,Building $@)
-	$(GOBUILD) -o $(BUILD_DIR)/$@ $(PKG)/cmd/$@
+	$(GOBUILD) -tags "$(BUILD_TAGS)" -o $(BUILD_DIR)/$@ $(PKG)/cmd/$@
 
 gitlab-workhorse:	$(TARGET_SETUP) $(shell find . -name '*.go' | grep -v '^\./_')
 	$(call message,Building $@)
-	$(GOBUILD) -o $(BUILD_DIR)/$@ $(PKG)
+	$(GOBUILD) -tags "$(BUILD_TAGS)" -o $(BUILD_DIR)/$@ $(PKG)
 
 .PHONY:	install
 install:	gitlab-workhorse gitlab-zip-cat gitlab-zip-metadata
@@ -67,13 +67,13 @@ install:	gitlab-workhorse gitlab-zip-cat gitlab-zip-metadata
 .PHONY:	test
 test: $(TARGET_SETUP) prepare-tests
 	$(call message,$@)
-	@go test $(LOCAL_PACKAGES)
+	@go test -tags "$(BUILD_TAGS)" $(LOCAL_PACKAGES)
 	@echo SUCCESS
 
 .PHONY:	coverage
 coverage:	$(TARGET_SETUP) prepare-tests
 	$(call message,$@)
-	@go test -cover -coverprofile=test.coverage $(LOCAL_PACKAGES)
+	@go test -tags "$(BUILD_TAGS)" -cover -coverprofile=test.coverage $(LOCAL_PACKAGES)
 	go tool cover -html=test.coverage -o coverage.html
 	rm -f test.coverage
 

README.md

@@ -204,6 +204,26 @@ the first priority during development.
 
 It is OK if a feature is only covered by integration tests.
 
+## Distributed Tracing
+
+Workhorse supports distributed tracing through [LabKit](https://gitlab.com/gitlab-org/labkit/) using [OpenTracing APIs](https://opentracing.io).
+
+By default, no tracing implementation is linked into the binary, but different OpenTracing providers can be linked in using [build tags](https://golang.org/pkg/go/build/#hdr-Build_Constraints)/[build constraints](https://golang.org/pkg/go/build/#hdr-Build_Constraints). This can be done by setting the `BUILD_TAGS` make variable.
+
+For more details of the supported providers, see LabKit, but as an example, for Jaeger tracing support, include the tags: `BUILD_TAGS="tracer_static tracer_static_jaeger"`.
+
+```shell
+make BUILD_TAGS="tracer_static tracer_static_jaeger"
+```
+
+Once Workhorse is compiled with an opentracing provider, the tracing configuration is configured via the `GITLAB_TRACING` environment variable.
+
+For example:
+
+```shell
+GITLAB_TRACING=opentracing://jaeger ./gitlab-workhorse
+```
+
 ## License
 
 This code is distributed under the MIT license, see the LICENSE file.

internal/gitaly/gitaly.go

@@ -11,6 +11,7 @@ import (
 	"google.golang.org/grpc"
 
 	grpccorrelation "gitlab.com/gitlab-org/labkit/correlation/grpc"
+	grpctracing "gitlab.com/gitlab-org/labkit/tracing/grpc"
 )
 
 type Server struct {
@@ -113,6 +114,7 @@ func newConnection(server Server) (*grpc.ClientConn, error) {
 		grpc.WithPerRPCCredentials(gitalyauth.RPCCredentialsV2(server.Token)),
 		grpc.WithStreamInterceptor(
 			grpc_middleware.ChainStreamClient(
+				grpctracing.StreamClientTracingInterceptor(),
 				grpc_prometheus.StreamClientInterceptor,
 				grpccorrelation.StreamClientCorrelationInterceptor(),
 			),
@@ -120,6 +122,7 @@ func newConnection(server Server) (*grpc.ClientConn, error) {
 
 		grpc.WithUnaryInterceptor(
 			grpc_middleware.ChainUnaryClient(
+				grpctracing.UnaryClientTracingInterceptor(),
 				grpc_prometheus.UnaryClientInterceptor,
 				grpccorrelation.UnaryClientCorrelationInterceptor(),
 			),

internal/objectstore/object.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"gitlab.com/gitlab-org/labkit/correlation"
+	"gitlab.com/gitlab-org/labkit/tracing"
 
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/helper"
 )
@@ -18,7 +19,7 @@ import (
 // that are more restrictive than for http.DefaultTransport,
 // they define shorter TLS Handshake, and more agressive connection closing
 // to prevent the connection hanging and reduce FD usage
-var httpTransport = correlation.NewInstrumentedRoundTripper(&http.Transport{
+var httpTransport = tracing.NewRoundTripper(correlation.NewInstrumentedRoundTripper(&http.Transport{
 	Proxy: http.ProxyFromEnvironment,
 	DialContext: (&net.Dialer{
 		Timeout:   30 * time.Second,
@@ -29,7 +30,7 @@ var httpTransport = correlation.NewInstrumentedRoundTripper(&http.Transport{
 	TLSHandshakeTimeout:   10 * time.Second,
 	ExpectContinueTimeout: 10 * time.Second,
 	ResponseHeaderTimeout: 30 * time.Second,
-})
+}))
 
 var httpClient = &http.Client{
 	Transport: httpTransport,

internal/sendurl/sendurl.go

@@ -10,6 +10,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 
 	"gitlab.com/gitlab-org/labkit/correlation"
+	"gitlab.com/gitlab-org/labkit/tracing"
 
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/helper"
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/log"
@@ -38,7 +39,7 @@ var rangeHeaderKeys = []string{
 // that are more restrictive than for http.DefaultTransport,
 // they define shorter TLS Handshake, and more agressive connection closing
 // to prevent the connection hanging and reduce FD usage
-var httpTransport = correlation.NewInstrumentedRoundTripper(&http.Transport{
+var httpTransport = tracing.NewRoundTripper(correlation.NewInstrumentedRoundTripper(&http.Transport{
 	Proxy: http.ProxyFromEnvironment,
 	DialContext: (&net.Dialer{
 		Timeout:   30 * time.Second,
@@ -49,7 +50,7 @@ var httpTransport = correlation.NewInstrumentedRoundTripper(&http.Transport{
 	TLSHandshakeTimeout:   10 * time.Second,
 	ExpectContinueTimeout: 10 * time.Second,
 	ResponseHeaderTimeout: 30 * time.Second,
-})
+}))
 
 var httpClient = &http.Client{
 	Transport: httpTransport,

internal/upstream/roundtripper/roundtripper.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"gitlab.com/gitlab-org/labkit/correlation"
+	"gitlab.com/gitlab-org/labkit/tracing"
 
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/badgateway"
 )
@@ -47,7 +48,11 @@ func NewBackendRoundTripper(backend *url.URL, socket string, proxyHeadersTimeout
 		panic("backend is nil and socket is empty")
 	}
 
-	return correlation.NewInstrumentedRoundTripper(badgateway.NewRoundTripper(developmentMode, transport))
+	return tracing.NewRoundTripper(
+		correlation.NewInstrumentedRoundTripper(
+			badgateway.NewRoundTripper(developmentMode, transport),
+		),
+	)
 }
 
 // NewTestBackendRoundTripper sets up a RoundTripper for testing purposes

internal/upstream/routes.go

@@ -7,6 +7,8 @@ import (
 
 	"github.com/gorilla/websocket"
 
+	"gitlab.com/gitlab-org/labkit/tracing"
+
 	apipkg "gitlab.com/gitlab-org/gitlab-workhorse/internal/api"
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/artifacts"
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/builds"
@@ -78,6 +80,10 @@ func route(method, regexpStr string, handler http.Handler, opts ...func(*routeOp
 
 	handler = denyWebsocket(handler)                      // Disallow websockets
 	handler = instrumentRoute(handler, method, regexpStr) // Add prometheus metrics
+	if options.tracing {
+		// Add distributed tracing
+		handler = tracing.Handler(handler)
+	}
 
 	return routeEntry{
 		method:   method,

internal/zipartifacts/open_archive.go

@@ -14,6 +14,7 @@ import (
 	"github.com/jfbus/httprs"
 
 	"gitlab.com/gitlab-org/labkit/correlation"
+	"gitlab.com/gitlab-org/labkit/tracing"
 
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/helper"
 )
@@ -25,7 +26,7 @@ var ErrNotAZip = errors.New("not a zip")
 var ErrArchiveNotFound = errors.New("archive not found")
 
 var httpClient = &http.Client{
-	Transport: correlation.NewInstrumentedRoundTripper(&http.Transport{
+	Transport: tracing.NewRoundTripper(correlation.NewInstrumentedRoundTripper(&http.Transport{
 		Proxy: http.ProxyFromEnvironment,
 		DialContext: (&net.Dialer{
 			Timeout:   30 * time.Second,
@@ -35,7 +36,7 @@ var httpClient = &http.Client{
 		TLSHandshakeTimeout:   10 * time.Second,
 		ExpectContinueTimeout: 10 * time.Second,
 		ResponseHeaderTimeout: 30 * time.Second,
-	}),
+	})),
 }
 
 // OpenArchive will open a zip.Reader from a local path or a remote object store URL

main.go

@@ -26,6 +26,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 
 	"gitlab.com/gitlab-org/labkit/correlation"
+	"gitlab.com/gitlab-org/labkit/tracing"
 
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/config"
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/log"
@@ -81,6 +82,8 @@ func main() {
 	startLogging(logConfig)
 	logger := log.NoContext()
 
+	tracing.Initialize(tracing.WithServiceName("gitlab-workhorse"))
+
 	backendURL, err := parseAuthBackend(*authBackend)
 	if err != nil {
 		logger.WithError(err).Fatal("invalid authBackend")

vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/DOC.md

+# grpc_opentracing
+`import "github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing"`
+
+* [Overview](#pkg-overview)
+* [Imported Packages](#pkg-imports)
+* [Index](#pkg-index)
+
+## <a name="pkg-overview">Overview</a>
+`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:
+<a href="http://opentracing.io/documentation/">http://opentracing.io/documentation/</a>
+<a href="https://github.com/opentracing/specification/blob/master/semantic_conventions.md">https://github.com/opentracing/specification/blob/master/semantic_conventions.md</a>
+
+## <a name="pkg-imports">Imported Packages</a>
+
+- [github.com/grpc-ecosystem/go-grpc-middleware](./../..)
+- [github.com/grpc-ecosystem/go-grpc-middleware/tags](./../../tags)
+- [github.com/grpc-ecosystem/go-grpc-middleware/util/metautils](./../../util/metautils)
+- [github.com/opentracing/opentracing-go](https://godoc.org/github.com/opentracing/opentracing-go)
+- [github.com/opentracing/opentracing-go/ext](https://godoc.org/github.com/opentracing/opentracing-go/ext)
+- [github.com/opentracing/opentracing-go/log](https://godoc.org/github.com/opentracing/opentracing-go/log)
+- [golang.org/x/net/context](https://godoc.org/golang.org/x/net/context)
+- [google.golang.org/grpc](https://godoc.org/google.golang.org/grpc)
+- [google.golang.org/grpc/grpclog](https://godoc.org/google.golang.org/grpc/grpclog)
+- [google.golang.org/grpc/metadata](https://godoc.org/google.golang.org/grpc/metadata)
+
+## <a name="pkg-index">Index</a>
+* [Constants](#pkg-constants)
+* [func ClientAddContextTags(ctx context.Context, tags opentracing.Tags) context.Context](#ClientAddContextTags)
+* [func StreamClientInterceptor(opts ...Option) grpc.StreamClientInterceptor](#StreamClientInterceptor)
+* [func StreamServerInterceptor(opts ...Option) grpc.StreamServerInterceptor](#StreamServerInterceptor)
+* [func UnaryClientInterceptor(opts ...Option) grpc.UnaryClientInterceptor](#UnaryClientInterceptor)
+* [func UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor](#UnaryServerInterceptor)
+* [type FilterFunc](#FilterFunc)
+* [type Option](#Option)
+  * [func WithFilterFunc(f FilterFunc) Option](#WithFilterFunc)
+  * [func WithTracer(tracer opentracing.Tracer) Option](#WithTracer)
+
+#### <a name="pkg-files">Package files</a>
+[client_interceptors.go](./client_interceptors.go) [doc.go](./doc.go) [id_extract.go](./id_extract.go) [metadata.go](./metadata.go) [options.go](./options.go) [server_interceptors.go](./server_interceptors.go) 
+
+## <a name="pkg-constants">Constants</a>
+``` go
+const (
+    TagTraceId = "trace.traceid"
+    TagSpanId  = "trace.spanid"
+)
+```
+
+## <a name="ClientAddContextTags">func</a> [ClientAddContextTags](./client_interceptors.go#L105)
+``` go
+func ClientAddContextTags(ctx context.Context, tags opentracing.Tags) context.Context
+```
+ClientAddContextTags returns a context with specified opentracing tags, which
+are used by UnaryClientInterceptor/StreamClientInterceptor when creating a
+new span.
+
+## <a name="StreamClientInterceptor">func</a> [StreamClientInterceptor](./client_interceptors.go#L35)
+``` go
+func StreamClientInterceptor(opts ...Option) grpc.StreamClientInterceptor
+```
+StreamClientInterceptor returns a new streaming client interceptor for OpenTracing.
+
+## <a name="StreamServerInterceptor">func</a> [StreamServerInterceptor](./server_interceptors.go#L37)
+``` go
+func StreamServerInterceptor(opts ...Option) grpc.StreamServerInterceptor
+```
+StreamServerInterceptor returns a new streaming server interceptor for OpenTracing.
+
+## <a name="UnaryClientInterceptor">func</a> [UnaryClientInterceptor](./client_interceptors.go#L21)
+``` go
+func UnaryClientInterceptor(opts ...Option) grpc.UnaryClientInterceptor
+```
+UnaryClientInterceptor returns a new unary client interceptor for OpenTracing.
+
+## <a name="UnaryServerInterceptor">func</a> [UnaryServerInterceptor](./server_interceptors.go#L23)
+``` go
+func UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor
+```
+UnaryServerInterceptor returns a new unary server interceptor for OpenTracing.
+
+## <a name="FilterFunc">type</a> [FilterFunc](./options.go#L22)
+``` go
+type FilterFunc func(ctx context.Context, fullMethodName string) bool
+```
+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.
+
+## <a name="Option">type</a> [Option](./options.go#L41)
+``` go
+type Option func(*options)
+```
+
+### <a name="WithFilterFunc">func</a> [WithFilterFunc](./options.go#L44)
+``` go
+func WithFilterFunc(f FilterFunc) Option
+```
+WithFilterFunc customizes the function used for deciding whether a given call is traced or not.
+
+### <a name="WithTracer">func</a> [WithTracer](./options.go#L51)
+``` go
+func WithTracer(tracer opentracing.Tracer) Option
+```
+WithTracer sets a custom tracer to be used for this middleware, otherwise the opentracing.GlobalTracer is used.
+
+- - -
+Generated by [godoc2ghmd](https://github.com/GandalfUK/godoc2ghmd)
\ No newline at end of file

vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/README.md

+# grpc_opentracing
+`import "github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing"`
+
+* [Overview](#pkg-overview)
+* [Imported Packages](#pkg-imports)
+* [Index](#pkg-index)
+
+## <a name="pkg-overview">Overview</a>
+`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:
+<a href="http://opentracing.io/documentation/">http://opentracing.io/documentation/</a>
+<a href="https://github.com/opentracing/specification/blob/master/semantic_conventions.md">https://github.com/opentracing/specification/blob/master/semantic_conventions.md</a>
+
+## <a name="pkg-imports">Imported Packages</a>
+
+- [github.com/grpc-ecosystem/go-grpc-middleware](./../..)
+- [github.com/grpc-ecosystem/go-grpc-middleware/tags](./../../tags)
+- [github.com/grpc-ecosystem/go-grpc-middleware/util/metautils](./../../util/metautils)
+- [github.com/opentracing/opentracing-go](https://godoc.org/github.com/opentracing/opentracing-go)
+- [github.com/opentracing/opentracing-go/ext](https://godoc.org/github.com/opentracing/opentracing-go/ext)
+- [github.com/opentracing/opentracing-go/log](https://godoc.org/github.com/opentracing/opentracing-go/log)
+- [golang.org/x/net/context](https://godoc.org/golang.org/x/net/context)
+- [google.golang.org/grpc](https://godoc.org/google.golang.org/grpc)
+- [google.golang.org/grpc/grpclog](https://godoc.org/google.golang.org/grpc/grpclog)
+- [google.golang.org/grpc/metadata](https://godoc.org/google.golang.org/grpc/metadata)
+
+## <a name="pkg-index">Index</a>
+* [Constants](#pkg-constants)
+* [func ClientAddContextTags(ctx context.Context, tags opentracing.Tags) context.Context](#ClientAddContextTags)
+* [func StreamClientInterceptor(opts ...Option) grpc.StreamClientInterceptor](#StreamClientInterceptor)
+* [func StreamServerInterceptor(opts ...Option) grpc.StreamServerInterceptor](#StreamServerInterceptor)
+* [func UnaryClientInterceptor(opts ...Option) grpc.UnaryClientInterceptor](#UnaryClientInterceptor)
+* [func UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor](#UnaryServerInterceptor)
+* [type FilterFunc](#FilterFunc)
+* [type Option](#Option)
+  * [func WithFilterFunc(f FilterFunc) Option](#WithFilterFunc)
+  * [func WithTracer(tracer opentracing.Tracer) Option](#WithTracer)
+
+#### <a name="pkg-files">Package files</a>
+[client_interceptors.go](./client_interceptors.go) [doc.go](./doc.go) [id_extract.go](./id_extract.go) [metadata.go](./metadata.go) [options.go](./options.go) [server_interceptors.go](./server_interceptors.go) 
+
+## <a name="pkg-constants">Constants</a>
+``` go
+const (
+    TagTraceId = "trace.traceid"
+    TagSpanId  = "trace.spanid"
+)
+```
+
+## <a name="ClientAddContextTags">func</a> [ClientAddContextTags](./client_interceptors.go#L105)
+``` go
+func ClientAddContextTags(ctx context.Context, tags opentracing.Tags) context.Context
+```
+ClientAddContextTags returns a context with specified opentracing tags, which
+are used by UnaryClientInterceptor/StreamClientInterceptor when creating a
+new span.
+
+## <a name="StreamClientInterceptor">func</a> [StreamClientInterceptor](./client_interceptors.go#L35)
+``` go
+func StreamClientInterceptor(opts ...Option) grpc.StreamClientInterceptor
+```
+StreamClientInterceptor returns a new streaming client interceptor for OpenTracing.
+
+## <a name="StreamServerInterceptor">func</a> [StreamServerInterceptor](./server_interceptors.go#L37)
+``` go
+func StreamServerInterceptor(opts ...Option) grpc.StreamServerInterceptor
+```
+StreamServerInterceptor returns a new streaming server interceptor for OpenTracing.
+
+## <a name="UnaryClientInterceptor">func</a> [UnaryClientInterceptor](./client_interceptors.go#L21)
+``` go
+func UnaryClientInterceptor(opts ...Option) grpc.UnaryClientInterceptor
+```
+UnaryClientInterceptor returns a new unary client interceptor for OpenTracing.
+
+## <a name="UnaryServerInterceptor">func</a> [UnaryServerInterceptor](./server_interceptors.go#L23)
+``` go
+func UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor
+```
+UnaryServerInterceptor returns a new unary server interceptor for OpenTracing.
+
+## <a name="FilterFunc">type</a> [FilterFunc](./options.go#L22)
+``` go
+type FilterFunc func(ctx context.Context, fullMethodName string) bool
+```
+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.
+
+## <a name="Option">type</a> [Option](./options.go#L41)
+``` go
+type Option func(*options)
+```
+
+### <a name="WithFilterFunc">func</a> [WithFilterFunc](./options.go#L44)
+``` go
+func WithFilterFunc(f FilterFunc) Option
+```
+WithFilterFunc customizes the function used for deciding whether a given call is traced or not.
+
+### <a name="WithTracer">func</a> [WithTracer](./options.go#L51)
+``` go
+func WithTracer(tracer opentracing.Tracer) Option
+```
+WithTracer sets a custom tracer to be used for this middleware, otherwise the opentracing.GlobalTracer is used.
+
+- - -
+Generated by [godoc2ghmd](https://github.com/GandalfUK/godoc2ghmd)
\ No newline at end of file

vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/client_interceptors.go

+// 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()
+}

vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/doc.go

+// 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

vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/id_extract.go

+// Copyright 2017 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_opentracing
+
+import (
+	"strings"
+
+	"github.com/grpc-ecosystem/go-grpc-middleware/tags"
+	"github.com/opentracing/opentracing-go"
+	"google.golang.org/grpc/grpclog"
+)
+
+const (
+	TagTraceId = "trace.traceid"
+	TagSpanId  = "trace.spanid"
+)
+
+// hackyInjectOpentracingIdsToTags writes the given context to the 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
+func hackyInjectOpentracingIdsToTags(span opentracing.Span, tags grpc_ctxtags.Tags) {
+	if err := span.Tracer().Inject(span.Context(), opentracing.HTTPHeaders, &hackyTagsCarrier{tags}); err != nil {
+		grpclog.Printf("grpc_opentracing: failed extracting trace info into ctx %v", err)
+	}
+}
+
+// hackyTagsCarrier is a really hacky way of
+type hackyTagsCarrier struct {
+	grpc_ctxtags.Tags
+}
+
+func (t *hackyTagsCarrier) Set(key, val string) {
+	if strings.Contains(key, "traceid") || strings.Contains(strings.ToLower(key), "traceid") {
+		t.Tags.Set(TagTraceId, val) // this will most likely be base-16 (hex) encoded
+	} else if (strings.Contains(key, "spanid") && !strings.Contains(key, "parent")) || (strings.Contains(strings.ToLower(key), "spanid") && !strings.Contains(strings.ToLower(key), "parent")) {
+		t.Tags.Set(TagSpanId, val) // this will most likely be base-16 (hex) encoded
+	}
+}

vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/metadata.go

+// 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
+}

vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/options.go

+// 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
+	}
+}

vendor/github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing/server_interceptors.go

+// 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,
+	)
+	hackyInjectOpentracingIdsToTags(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()
+}

vendor/github.com/lightstep/lightstep-tracer-go/CHANGELOG.md

+# Changelog
+
+## [Pending Release](https://github.com/lightstep/lightstep-tracer-go/compare/v0.15.6...HEAD)
+* Requires go >= 1.7
+* Imports `context` via the standard library instead of `golang.org/x/net/context`
+* Fixes [#182](https://github.com/lightstep/lightstep-tracer-go/issues/182), so that `StartSpan` can now take `SpanReference`s to non-LightStep `SpanContext`s use
+
+## [v0.15.6](https://github.com/lightstep/lightstep-tracer-go/compare/v0.15.5...v0.15.6)
+
+* Minor update to `sendspan` to make it easier to pick which transport protocol to use.
+* Add a new field to Options: DialOptions. These allow setting custom grpc dial options when using grpc.
+  * This is necessary to have customer balancers or interceptors.
+  * DialOptions shouldn't be set unless it is needed, it will default correctly.
+* Added a new field to Endpoint: Scheme. Scheme can be used to override the default schemes (http/https) or set a custom scheme (for grpc).
+  * This is necessary for using custom grpc resolvers.
+  * If callers are using struct construction without field names (i.e. Endpoint{"host", port, ...}), they will need to add a new field (scheme = "").
+  * Scheme shouldn't be set unless it needs to overridden, it will default correctly.
+
+## [v0.15.5](https://github.com/lightstep/lightstep-tracer-go/compare/v0.15.4...v0.15.5)
+* Internal performance optimizations and a bug fix for issue [#161](https://github.com/lightstep/lightstep-tracer-go/issues/161)
+
+## [v0.15.4](https://github.com/lightstep/lightstep-tracer-go/compare/v0.15.3...v0.15.4)
+* This change affects LightStep's internal testing, not a functional change.
+
+## [v0.15.3](https://github.com/lightstep/lightstep-tracer-go/compare/v0.15.2...v0.15.3)
+* Adds compatibility for io.Writer and io.Reader in Inject/Extract, as required by Open Tracing.
+
+## [v0.15.2](https://github.com/lightstep/lightstep-tracer-go/compare/v0.15.1...v0.15.2)
+* Adds lightstep.GetLightStepReporterID.
+
+## [v0.15.1](https://github.com/lightstep/lightstep-tracer-go/compare/v0.15.0...v0.15.1)
+* Adds Gopkg.toml
+
+## [v0.15.0](https://github.com/lightstep/lightstep-tracer-go/compare/v0.14.0...v0.15.0)
+* We are replacing the internal diagnostic logging with a more flexible “Event” framework. This enables you to track and understand tracer problems with metrics and logging tools of your choice.
+* We are also changed the types of the Close() and Flush() methods to take a context parameter to support cancellation. These changes are *not* backwards compatible and *you will need to update your instrumentation*. We are providing a NewTracerv0_14() method that is a drop-in replacement for the previous version.
+
+## [v0.14.0](https://github.com/lightstep/lightstep-tracer-go/compare/v0.13.0...v0.14.0)
+* Flush buffer syncronously on Close.
+* Flush twice if a flush is already in flight.
+* Remove gogo in favor of golang/protobuf.
+* Requires grpc-go >= 1.4.0.
+
+## [v0.13.0](https://github.com/lightstep/lightstep-tracer-go/compare/v0.12.0...v0.13.0) 
+* BasicTracer has been removed.
+* Tracer now takes a SpanRecorder as an option.
+* Tracer interface now includes Close and Flush.
+* Tests redone with ginkgo/gomega.
+
+## [v0.12.0](https://github.com/lightstep/lightstep-tracer-go/compare/v0.11.0...v0.12.0)
+* Added CloseTracer function to flush and close a lightstep recorder.
+
+## [v0.11.0](https://github.com/lightstep/lightstep-tracer-go/compare/v0.10.0...v0.11.0)
+* Thrift transport is now deprecated, gRPC is the default.

vendor/github.com/lightstep/lightstep-tracer-go/Gopkg.lock

+# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
+
+
+[[projects]]
+  branch = "master"
+  digest = "1:3b760d3b93f994df8eb1d9ebfad17d3e9e37edcb7f7efaa15b427c0d7a64f4e4"
+  name = "github.com/golang/protobuf"
+  packages = [
+    "proto",
+    "protoc-gen-go/descriptor",
+    "ptypes",
+    "ptypes/any",
+    "ptypes/duration",
+    "ptypes/timestamp",
+  ]
+  pruneopts = ""
+  revision = "1e59b77b52bf8e4b449a57e6f79f21226d571845"
+
+[[projects]]
+  branch = "master"
+  digest = "1:b486888585e9070ef97f0c9b2df560e007dc2eafb8ace96b13a2cb85ccec3df1"
+  name = "github.com/lightstep/thrift"
+  packages = ["lib/go/thrift"]
+  pruneopts = ""
+  revision = "de6c3c01b88c1fc8ae76cec4a30f0441ef55a4a4"
+
+[[projects]]
+  digest = "1:32b27072cd55bd2fb7244de0425943d125da6a552ae2b6517cdd965a662baf18"
+  name = "github.com/onsi/ginkgo"
+  packages = [
+    ".",
+    "config",
+    "internal/codelocation",
+    "internal/containernode",
+    "internal/failer",
+    "internal/leafnodes",
+    "internal/remote",
+    "internal/spec",
+    "internal/spec_iterator",
+    "internal/specrunner",
+    "internal/suite",
+    "internal/testingtproxy",
+    "internal/writer",
+    "reporters",
+    "reporters/stenographer",
+    "reporters/stenographer/support/go-colorable",
+    "reporters/stenographer/support/go-isatty",
+    "types",
+  ]
+  pruneopts = ""
+  revision = "9eda700730cba42af70d53180f9dcce9266bc2bc"
+  version = "v1.4.0"
+
+[[projects]]
+  digest = "1:a4e59d0b2821c983b58c317f141cd77df20570979632da8a7a352e5d12698de7"
+  name = "github.com/onsi/gomega"
+  packages = [
+    ".",
+    "format",
+    "internal/assertion",
+    "internal/asyncassertion",
+    "internal/oraclematcher",
+    "internal/testingtsupport",
+    "matchers",
+    "matchers/support/goraph/bipartitegraph",
+    "matchers/support/goraph/edge",
+    "matchers/support/goraph/node",
+    "matchers/support/goraph/util",
+    "types",
+  ]
+  pruneopts = ""
+  revision = "c893efa28eb45626cdaa76c9f653b62488858837"
+  version = "v1.2.0"
+
+[[projects]]
+  digest = "1:78fb99d6011c2ae6c72f3293a83951311147b12b06a5ffa43abf750c4fab6ac5"
+  name = "github.com/opentracing/opentracing-go"
+  packages = [
+    ".",
+    "log",
+  ]
+  pruneopts = ""
+  revision = "1949ddbfd147afd4d964a9f00b24eb291e0e7c38"
+  version = "v1.0.2"
+
+[[projects]]
+  branch = "master"
+  digest = "1:950b672f2ee80d0fc4c95a15a976ba9ee573a6fb8ede8a777770b2230776367e"
+  name = "golang.org/x/net"
+  packages = [
+    "context",
+    "html",
+    "html/atom",
+    "html/charset",
+    "http2",
+    "http2/hpack",
+    "idna",
+    "internal/timeseries",
+    "lex/httplex",
+    "trace",
+  ]
+  pruneopts = ""
+  revision = "dc871a5d77e227f5bbf6545176ef3eeebf87e76e"
+
+[[projects]]
+  branch = "master"
+  digest = "1:5da11ab130476e2736f32140f3c1aed2a3a96e9ba8963711a7d38db783d042bd"
+  name = "golang.org/x/sys"
+  packages = ["unix"]
+  pruneopts = ""
+  revision = "a0f4589a76f1f83070cb9e5613809e1d07b97c13"
+
+[[projects]]
+  branch = "master"
+  digest = "1:1c70f7bb89783a026dc32920575a3feef48e065ef6e170ad227903e8194d7a36"
+  name = "golang.org/x/text"
+  packages = [
+    "collate",
+    "collate/build",
+    "encoding",
+    "encoding/charmap",
+    "encoding/htmlindex",
+    "encoding/internal",
+    "encoding/internal/identifier",
+    "encoding/japanese",
+    "encoding/korean",
+    "encoding/simplifiedchinese",
+    "encoding/traditionalchinese",
+    "encoding/unicode",
+    "internal/colltab",
+    "internal/gen",
+    "internal/tag",
+    "internal/triegen",
+    "internal/ucd",
+    "internal/utf8internal",
+    "language",
+    "runes",
+    "secure/bidirule",
+    "transform",
+    "unicode/bidi",
+    "unicode/cldr",
+    "unicode/norm",
+    "unicode/rangetable",
+  ]
+  pruneopts = ""
+  revision = "be25de41fadfae372d6470bda81ca6beb55ef551"
+
+[[projects]]
+  branch = "master"
+  digest = "1:6c15114fafeac4c833544476dec4207a3476799d50ab5165af79eb97806884cf"
+  name = "google.golang.org/genproto"
+  packages = [
+    "googleapis/api/annotations",
+    "googleapis/rpc/status",
+  ]
+  pruneopts = ""
+  revision = "7f0da29060c682909f650ad8ed4e515bd74fa12a"
+
+[[projects]]
+  digest = "1:6c00b4702c146631d30396090d40bfc0486f8b3af5c976d6f0daf2bc737cd7b2"
+  name = "google.golang.org/grpc"
+  packages = [
+    ".",
+    "balancer",
+    "balancer/roundrobin",
+    "codes",
+    "connectivity",
+    "credentials",
+    "encoding",
+    "grpclb/grpc_lb_v1/messages",
+    "grpclog",
+    "internal",
+    "keepalive",
+    "metadata",
+    "naming",
+    "peer",
+    "resolver",
+    "resolver/dns",
+    "resolver/manual",
+    "resolver/passthrough",
+    "stats",
+    "status",
+    "tap",
+    "transport",
+  ]
+  pruneopts = ""
+  revision = "be077907e29fdb945d351e4284eb5361e7f8924e"
+  version = "v1.8.1"
+
+[[projects]]
+  branch = "v2"
+  digest = "1:f769ed60e075e4221612c2f4162fccc9d3795ef358fa463425e3b3d7a5debb27"
+  name = "gopkg.in/yaml.v2"
+  packages = ["."]
+  pruneopts = ""
+  revision = "287cf08546ab5e7e37d55a84f7ed3fd1db036de5"
+
+[solve-meta]
+  analyzer-name = "dep"
+  analyzer-version = 1
+  input-imports = [
+    "github.com/golang/protobuf/proto",
+    "github.com/golang/protobuf/ptypes/timestamp",
+    "github.com/lightstep/thrift/lib/go/thrift",
+    "github.com/onsi/ginkgo",
+    "github.com/onsi/gomega",
+    "github.com/onsi/gomega/types",
+    "github.com/opentracing/opentracing-go",
+    "github.com/opentracing/opentracing-go/log",
+    "golang.org/x/net/context",
+    "golang.org/x/net/http2",
+    "google.golang.org/genproto/googleapis/api/annotations",
+    "google.golang.org/grpc",
+    "google.golang.org/grpc/credentials",
+  ]
+  solver-name = "gps-cdcl"
+  solver-version = 1

vendor/github.com/lightstep/lightstep-tracer-go/Gopkg.toml

+[[constraint]]
+  name = "github.com/onsi/ginkgo"
+  version = "1.4.0"
+
+[[constraint]]
+  name = "github.com/onsi/gomega"
+  version = "1.2.0"
+
+[[constraint]]
+  name = "github.com/opentracing/opentracing-go"
+  version = "1.0.2"
+
+[[constraint]]
+  branch = "master"
+  name = "golang.org/x/net"
+
+[[constraint]]
+  name = "google.golang.org/grpc"
+  version = "1.4.3"
+
+[[constraint]]
+  name = "github.com/lightstep/thrift"
+  branch = "master"

vendor/github.com/lightstep/lightstep-tracer-go/LICENSE

+The MIT License (MIT)
+
+Copyright (c) 2016 
+
+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.

vendor/github.com/lightstep/lightstep-tracer-go/Makefile

+# tools
+GO=go
+DOCKER_PRESENT = $(shell command -v docker 2> /dev/null)
+
+LOCAL_GOPATH = $(PWD)/../../../../
+
+default: build
+.PHONY: default build test
+
+# generate_fake: runs counterfeiter in docker container to generate fake classes
+# $(1) output file path
+# $(2) input file path
+# $(3) class name
+define generate_fake
+	docker run --rm -v $(LOCAL_GOPATH):/usergo \
+	  lightstep/gobuild:latest /bin/bash -c "\
+	  cd /usergo/src/github.com/lightstep/lightstep-tracer-go; \
+	  counterfeiter -o $(1) $(2) $(3)"
+endef
+# Thrift
+ifeq (,$(wildcard $(LIGHTSTEP_REPO_ROOT)/go/src/github.com/lightstep/common-go/crouton.thrift))
+lightstep_thrift/constants.go:
+else
+# LightStep-specific: rebuilds the LightStep thrift protocol files.
+# Assumes the command is run within the LightStep development
+# environment (LIGHTSTEP_REPO_ROOT is set).
+lightstep_thrift/constants.go: $(LIGHTSTEP_REPO_ROOT)/go/src/github.com/lightstep/common-go/crouton.thrift
+	docker run --rm -v "$(LIGHTSTEP_REPO_ROOT)/go/src/github.com/lightstep/common-go:/data" -v "$(PWD):/out" thrift:0.9.2 \
+	  thrift --gen go:package_prefix='github.com/lightstep/lightstep-tracer-go/',thrift_import='github.com/lightstep/lightstep-tracer-go/thrift_0_9_2/lib/go/thrift' -out /out /data/crouton.thrift
+	rm -rf lightstep_thrift/reporting_service-remote
+endif
+
+lightstepfakes/fake_recorder.go: options.go
+	$(call generate_fake,lightstepfakes/fake_recorder.go,options.go,SpanRecorder)
+
+lightstep_thrift/lightstep_thriftfakes/fake_reporting_service.go: lightstep_thrift/reportingservice.go
+	$(call generate_fake,lightstep_thrift/lightstep_thriftfakes/fake_reporting_service.go,lightstep_thrift/reportingservice.go,ReportingService)
+
+collectorpb/collectorpbfakes/fake_collector_service_client.go: collectorpb/collector.pb.go
+	$(call generate_fake,collectorpb/collectorpbfakes/fake_collector_service_client.go,collectorpb/collector.pb.go,CollectorServiceClient)
+
+# gRPC
+ifeq (,$(wildcard lightstep-tracer-common/collector.proto))
+collectorpb/collector.pb.go:
+else
+collectorpb/collector.pb.go: lightstep-tracer-common/collector.proto
+	docker run --rm -v $(shell pwd)/lightstep-tracer-common:/input:ro -v $(shell pwd)/collectorpb:/output \
+	  lightstep/grpc-gateway:latest \
+	  protoc -I/root/go/src/tmp/vendor/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis --go_out=plugins=grpc:/output --proto_path=/input /input/collector.proto
+endif
+
+# gRPC
+ifeq (,$(wildcard lightstep-tracer-common/collector.proto))
+lightsteppb/lightstep.pb.go:
+else
+lightsteppb/lightstep.pb.go: lightstep-tracer-common/lightstep.proto
+	docker run --rm -v $(shell pwd)/lightstep-tracer-common:/input:ro -v $(shell pwd)/lightsteppb:/output \
+	  lightstep/protoc:latest \
+	  protoc --go_out=plugins=grpc:/output --proto_path=/input /input/lightstep.proto
+endif
+
+test: lightstep_thrift/constants.go collectorpb/collector.pb.go lightsteppb/lightstep.pb.go \
+		collectorpb/collectorpbfakes/fake_collector_service_client.go \
+		lightstep_thrift/lightstep_thriftfakes/fake_reporting_service.go lightstepfakes/fake_recorder.go
+ifeq ($(DOCKER_PRESENT),)
+	$(error "docker not found. Please install from https://www.docker.com/")
+endif
+	docker run --rm -v $(LOCAL_GOPATH):/usergo lightstep/gobuild:latest \
+	  ginkgo -race -p /usergo/src/github.com/lightstep/lightstep-tracer-go
+	bash -c "! git grep -q '[g]ithub.com/golang/glog'"
+
+build: lightstep_thrift/constants.go collectorpb/collector.pb.go lightsteppb/lightstep.pb.go \
+		collectorpb/collectorpbfakes/fake_collector_service_client.go version.go \
+		lightstep_thrift/lightstep_thriftfakes/fake_reporting_service.go lightstepfakes/fake_recorder.go
+ifeq ($(DOCKER_PRESENT),)
+	$(error "docker not found. Please install from https://www.docker.com/")
+endif
+	${GO} build github.com/lightstep/lightstep-tracer-go
+
+# When releasing significant changes, make sure to update the semantic
+# version number in `./VERSION`, merge changes, then run `make release_tag`.
+version.go: VERSION
+	./tag_version.sh
+
+release_tag:
+	git tag -a v`cat ./VERSION`
+	git push origin v`cat ./VERSION`

vendor/github.com/lightstep/lightstep-tracer-go/README.md

+# lightstep-tracer-go
+
+[![Circle CI](https://circleci.com/gh/lightstep/lightstep-tracer-go.svg?style=shield)](https://circleci.com/gh/lightstep/lightstep-tracer-go)
+[![MIT license](http://img.shields.io/badge/license-MIT-blue.svg)](http://opensource.org/licenses/MIT)
+[![GoDoc](https://godoc.org/github.com/lightstep/lightstep-tracer-go?status.svg)](https://godoc.org/github.com/lightstep/lightstep-tracer-go)
+
+The LightStep distributed tracing library for Go.
+
+## Installation
+
+```
+$ go get 'github.com/lightstep/lightstep-tracer-go'
+```
+
+## API Documentation
+
+Godoc: https://godoc.org/github.com/lightstep/lightstep-tracer-go
+
+## Initialization: Starting a new tracer
+To initialize a tracer, configure it with a valid Access Token and optional tuning parameters. Register the tracer as the OpenTracing global tracer so that it will become available to your installed intstrumentations libraries.
+
+```go
+import (
+  "github.com/opentracing/opentracing-go"
+  "github.com/lightstep/lightstep-tracer-go"
+)
+
+func main() {
+  lightstepTracer := lightstep.NewTracer(lightstep.Options{
+    AccessToken: "YourAccessToken",
+  })
+
+  opentracing.SetGlobalTracer(lightstepTracer)
+}
+```
+
+## Instrumenting Code: Using the OpenTracing API
+
+All instrumentation should be done through the OpenTracing API, rather than using the lightstep tracer type directly. For API documentation and advice on instrumentation in general, see the opentracing godocs and the opentracing website.
+
+- https://godoc.org/github.com/opentracing/opentracing-go
+- http://opentracing.io
+
+## Flushing and Closing: Managing the tracer lifecycle
+
+As part of managaing your application lifecycle, the lightstep tracer extends the `opentracing.Tracer` interface with methods for manual flushing and closing. To access these methods, you can take the global tracer and typecast it to a `lightstep.Tracer`. As a convenience, the lightstep package provides static methods which perform the typecasting.
+
+```go
+import (
+  "context"
+  "github.com/opentracing/opentracing-go"
+  "github.com/lightstep/lightstep-tracer-go"
+)
+
+func shutdown(ctx context.Context) {
+  // access the running tracer
+  tracer := opentracing.GlobalTracer()
+    
+  // typecast from opentracing.Tracer to lightstep.Tracer
+  lsTracer, ok := tracer.(lightstep.Tracer)
+  if (!ok) { 
+    return 
+  }
+  lsTracer.Close(ctx)
+
+  // or use static methods
+  lightstep.Close(ctx, tracer)
+}
+```
+
+## Event Handling: Observing the LightStep tracer
+In order to connect diagnostic information from the lightstep tracer into an application's logging and metrics systems, inject an event handler using the `OnEvent` static method. Events may be typecast to check for errors or specific events such as status reports.
+
+```go
+import (
+  "example/logger"
+  "example/metrics"
+  "github.com/lightstep/lightstep-tracer-go"
+)
+
+logAndMetricsHandler := func(event lightstep.Event){
+  switch event := event.(type) {
+  case EventStatusReport:
+    metrics.Count("tracer.dropped_spans", event.DroppedSpans())
+  case ErrorEvent:
+    logger.Error("LS Tracer error: %s", event)
+  default:
+    logger.Info("LS Tracer info: %s", event)
+  }
+}
+
+func main() {
+  // setup event handler first to catch startup errors
+  lightstep.SetGlobalEventHandler(logAndMetricsHandler)
+  
+  lightstepTracer := lightstep.NewTracer(lightstep.Options{
+    AccessToken: "YourAccessToken",
+  })
+
+  opentracing.SetGlobalTracer(lightstepTracer)
+}
+```
+
+Event handlers will receive events from any active tracers, as well as errors in static functions. It is suggested that you set up event handling before initializing your tracer to catch any errors on initialization.
+
+## Advanced Configuration: Transport and Serialization Protocols
+
+By default, the tracer will send information to LightStep using GRPC and Protocol Buffers which is the recommended configuration. If there are no specific transport protocol needs you have, there is no need to change this default.
+
+There are three total options for transport protocols:
+
+- [Protocol Buffers](https://developers.google.com/protocol-buffers/) over [GRPC](https://grpc.io/) - The recommended, default, and most performant solution.
+- [Thrift](https://thrift.apache.org/) over HTTP - A legacy implementation not recommended for new deployments.
+- \[ EXPERIMENTAL \] [Protocol Buffers](https://developers.google.com/protocol-buffers/) over HTTP - New transport protocol supported for use cases where GRPC isn't an option. In order to enable HTTP you will need to configure the LightStep collectors receiving the data to accept HTTP traffic. Reach out to LightStep for support in this.
+
+You can configure which transport protocol the tracer uses using the `UseGRPC`, `UseThrift`, and `UseHttp` flags in the options.
\ No newline at end of file

vendor/github.com/lightstep/lightstep-tracer-go/VERSION

+0.15.6

vendor/github.com/lightstep/lightstep-tracer-go/collector_client.go

+package lightstep
+
+import (
+	"context"
+	"io"
+	"net/http"
+
+	cpb "github.com/lightstep/lightstep-tracer-go/collectorpb"
+	"github.com/lightstep/lightstep-tracer-go/lightstep_thrift"
+)
+
+// Connection describes a closable connection. Exposed for testing.
+type Connection interface {
+	io.Closer
+}
+
+// ConnectorFactory is for testing purposes.
+type ConnectorFactory func() (interface{}, Connection, error)
+
+// collectorResponse encapsulates internal thrift/grpc responses.
+type collectorResponse interface {
+	GetErrors() []string
+	Disable() bool
+}
+
+type reportRequest struct {
+	thriftRequest *lightstep_thrift.ReportRequest
+	protoRequest  *cpb.ReportRequest
+	httpRequest   *http.Request
+}
+
+// collectorClient encapsulates internal thrift/grpc transports.
+type collectorClient interface {
+	Report(context.Context, reportRequest) (collectorResponse, error)
+	Translate(context.Context, *reportBuffer) (reportRequest, error)
+	ConnectClient() (Connection, error)
+	ShouldReconnect() bool
+}
+
+func newCollectorClient(opts Options, reporterID uint64, attributes map[string]string) (collectorClient, error) {
+	if opts.UseThrift {
+		return newThriftCollectorClient(opts, reporterID, attributes), nil
+	}
+
+	if opts.UseHttp {
+		return newHTTPCollectorClient(opts, reporterID, attributes)
+	}
+
+	if opts.UseGRPC {
+		return newGrpcCollectorClient(opts, reporterID, attributes), nil
+	}
+
+	// No transport specified, defaulting to GRPC
+	return newGrpcCollectorClient(opts, reporterID, attributes), nil
+}

vendor/github.com/lightstep/lightstep-tracer-go/collector_client_grpc.go

+package lightstep
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials"
+
+	// N.B.(jmacd): Do not use google.golang.org/glog in this package.
+	cpb "github.com/lightstep/lightstep-tracer-go/collectorpb"
+)
+
+const (
+	spansDropped     = "spans.dropped"
+	logEncoderErrors = "log_encoder.errors"
+)
+
+var (
+	intType = reflect.TypeOf(int64(0))
+)
+
+// grpcCollectorClient specifies how to send reports back to a LightStep
+// collector via grpc.
+type grpcCollectorClient struct {
+	// auth and runtime information
+	attributes map[string]string
+	reporterID uint64
+
+	// accessToken is the access token used for explicit trace collection requests.
+	accessToken        string
+	maxReportingPeriod time.Duration // set by GrpcOptions.MaxReportingPeriod
+	reconnectPeriod    time.Duration // set by GrpcOptions.ReconnectPeriod
+	reportingTimeout   time.Duration // set by GrpcOptions.ReportTimeout
+
+	// Remote service that will receive reports.
+	address       string
+	grpcClient    cpb.CollectorServiceClient
+	connTimestamp time.Time
+	dialOptions   []grpc.DialOption
+
+	// converters
+	converter *protoConverter
+
+	// For testing purposes only
+	grpcConnectorFactory ConnectorFactory
+}
+
+func newGrpcCollectorClient(opts Options, reporterID uint64, attributes map[string]string) *grpcCollectorClient {
+	rec := &grpcCollectorClient{
+		attributes:           attributes,
+		reporterID:           reporterID,
+		accessToken:          opts.AccessToken,
+		maxReportingPeriod:   opts.ReportingPeriod,
+		reconnectPeriod:      opts.ReconnectPeriod,
+		reportingTimeout:     opts.ReportTimeout,
+		dialOptions:          opts.DialOptions,
+		converter:            newProtoConverter(opts),
+		grpcConnectorFactory: opts.ConnFactory,
+	}
+
+	if len(opts.Collector.Scheme) > 0 {
+		rec.address = opts.Collector.urlWithoutPath()
+	} else {
+		rec.address = opts.Collector.SocketAddress()
+	}
+
+	rec.dialOptions = append(rec.dialOptions, grpc.WithDefaultCallOptions(grpc.MaxCallSendMsgSize(opts.GRPCMaxCallSendMsgSizeBytes)))
+	if opts.Collector.Plaintext {
+		rec.dialOptions = append(rec.dialOptions, grpc.WithInsecure())
+	} else {
+		rec.dialOptions = append(rec.dialOptions, grpc.WithTransportCredentials(credentials.NewClientTLSFromCert(nil, "")))
+	}
+
+	return rec
+}
+
+func (client *grpcCollectorClient) ConnectClient() (Connection, error) {
+	now := time.Now()
+	var conn Connection
+	if client.grpcConnectorFactory != nil {
+		uncheckedClient, transport, err := client.grpcConnectorFactory()
+		if err != nil {
+			return nil, err
+		}
+
+		grpcClient, ok := uncheckedClient.(cpb.CollectorServiceClient)
+		if !ok {
+			return nil, fmt.Errorf("gRPC connector factory did not provide valid client")
+		}
+
+		conn = transport
+		client.grpcClient = grpcClient
+	} else {
+		transport, err := grpc.Dial(client.address, client.dialOptions...)
+		if err != nil {
+			return nil, err
+		}
+
+		conn = transport
+		client.grpcClient = cpb.NewCollectorServiceClient(transport)
+	}
+	client.connTimestamp = now
+	return conn, nil
+}
+
+func (client *grpcCollectorClient) ShouldReconnect() bool {
+	return time.Since(client.connTimestamp) > client.reconnectPeriod
+}
+
+func (client *grpcCollectorClient) Report(ctx context.Context, req reportRequest) (collectorResponse, error) {
+	if req.protoRequest == nil {
+		return nil, fmt.Errorf("protoRequest cannot be null")
+	}
+	resp, err := client.grpcClient.Report(ctx, req.protoRequest)
+	if err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
+func (client *grpcCollectorClient) Translate(ctx context.Context, buffer *reportBuffer) (reportRequest, error) {
+	req := client.converter.toReportRequest(
+		client.reporterID,
+		client.attributes,
+		client.accessToken,
+		buffer,
+	)
+	return reportRequest{
+		protoRequest: req,
+	}, nil
+}

vendor/github.com/lightstep/lightstep-tracer-go/collector_client_http.go

+package lightstep
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/lightstep/lightstep-tracer-go/collectorpb"
+)
+
+var (
+	acceptHeader      = http.CanonicalHeaderKey("Accept")
+	contentTypeHeader = http.CanonicalHeaderKey("Content-Type")
+)
+
+const (
+	collectorHTTPMethod = "POST"
+	collectorHTTPPath   = "/api/v2/reports"
+	protoContentType    = "application/octet-stream"
+)
+
+// grpcCollectorClient specifies how to send reports back to a LightStep
+// collector via grpc.
+type httpCollectorClient struct {
+	// auth and runtime information
+	reporterID  uint64
+	accessToken string // accessToken is the access token used for explicit trace collection requests.
+	attributes  map[string]string
+
+	reportTimeout   time.Duration
+	reportingPeriod time.Duration
+
+	// Remote service that will receive reports.
+	url    *url.URL
+	client *http.Client
+
+	// converters
+	converter *protoConverter
+}
+
+type transportCloser struct {
+	*http.Transport
+}
+
+func (closer transportCloser) Close() error {
+	closer.CloseIdleConnections()
+	return nil
+}
+
+func newHTTPCollectorClient(
+	opts Options,
+	reporterID uint64,
+	attributes map[string]string,
+) (*httpCollectorClient, error) {
+	url, err := url.Parse(opts.Collector.URL())
+	if err != nil {
+		fmt.Println("collector config does not produce valid url", err)
+		return nil, err
+	}
+	url.Path = collectorHTTPPath
+
+	return &httpCollectorClient{
+		reporterID:      reporterID,
+		accessToken:     opts.AccessToken,
+		attributes:      attributes,
+		reportTimeout:   opts.ReportTimeout,
+		reportingPeriod: opts.ReportingPeriod,
+		url:             url,
+		converter:       newProtoConverter(opts),
+	}, nil
+}
+
+func (client *httpCollectorClient) ConnectClient() (Connection, error) {
+	// Use a transport independent from http.DefaultTransport to provide sane
+	// defaults that make sense in the context of the lightstep client. The
+	// differences are mostly on setting timeouts based on the report timeout
+	// and period.
+	transport := &http.Transport{
+		Proxy: http.ProxyFromEnvironment,
+		DialContext: (&net.Dialer{
+			Timeout:   client.reportTimeout / 2,
+			DualStack: true,
+		}).DialContext,
+		// The collector responses are very small, there is no point asking for
+		// a compressed payload, explicitly disabling it.
+		DisableCompression:     true,
+		IdleConnTimeout:        2 * client.reportingPeriod,
+		TLSHandshakeTimeout:    client.reportTimeout / 2,
+		ResponseHeaderTimeout:  client.reportTimeout,
+		ExpectContinueTimeout:  client.reportTimeout,
+		MaxResponseHeaderBytes: 64 * 1024, // 64 KB, just a safeguard
+	}
+
+	client.client = &http.Client{
+		Transport: transport,
+		Timeout:   client.reportTimeout,
+	}
+
+	return transportCloser{transport}, nil
+}
+
+func (client *httpCollectorClient) ShouldReconnect() bool {
+	// http.Transport will handle connection reuse under the hood
+	return false
+}
+
+func (client *httpCollectorClient) Report(context context.Context, req reportRequest) (collectorResponse, error) {
+	if req.httpRequest == nil {
+		return nil, fmt.Errorf("httpRequest cannot be null")
+	}
+
+	httpResponse, err := client.client.Do(req.httpRequest.WithContext(context))
+	if err != nil {
+		return nil, err
+	}
+	defer httpResponse.Body.Close()
+
+	response, err := client.toResponse(httpResponse)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, nil
+}
+
+func (client *httpCollectorClient) Translate(ctx context.Context, buffer *reportBuffer) (reportRequest, error) {
+
+	httpRequest, err := client.toRequest(ctx, buffer)
+	if err != nil {
+		return reportRequest{}, err
+	}
+	return reportRequest{
+		httpRequest: httpRequest,
+	}, nil
+}
+
+func (client *httpCollectorClient) toRequest(
+	context context.Context,
+	buffer *reportBuffer,
+) (*http.Request, error) {
+	protoRequest := client.converter.toReportRequest(
+		client.reporterID,
+		client.attributes,
+		client.accessToken,
+		buffer,
+	)
+
+	buf, err := proto.Marshal(protoRequest)
+	if err != nil {
+		return nil, err
+	}
+
+	requestBody := bytes.NewReader(buf)
+
+	request, err := http.NewRequest(collectorHTTPMethod, client.url.String(), requestBody)
+	if err != nil {
+		return nil, err
+	}
+	request = request.WithContext(context)
+	request.Header.Set(contentTypeHeader, protoContentType)
+	request.Header.Set(acceptHeader, protoContentType)
+
+	return request, nil
+}
+
+func (client *httpCollectorClient) toResponse(response *http.Response) (collectorResponse, error) {
+	if response.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("status code (%d) is not ok", response.StatusCode)
+	}
+
+	body, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	protoResponse := &collectorpb.ReportResponse{}
+	if err := proto.Unmarshal(body, protoResponse); err != nil {
+		return nil, err
+	}
+
+	return protoResponse, nil
+}

vendor/github.com/lightstep/lightstep-tracer-go/collector_client_thrift.go

+package lightstep
+
+import (
+	"context"
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/lightstep/lightstep-tracer-go/lightstep_thrift"
+	"github.com/lightstep/thrift/lib/go/thrift"
+)
+
+// thriftCollectorClient specifies how to send reports back to a LightStep
+// collector via thrift
+type thriftCollectorClient struct {
+	// auth and runtime information
+	auth       *lightstep_thrift.Auth
+	attributes map[string]string
+	startTime  time.Time
+	reporterID uint64
+
+	maxReportingPeriod time.Duration
+	// Remote service that will receive reports
+	thriftClient lightstep_thrift.ReportingService
+
+	// apiURL is the base URL of the LightStep web API, used for
+	// explicit trace collection requests.
+	collectorURL string
+
+	// AccessToken is the access token used for explicit trace
+	// collection requests.
+	AccessToken string
+
+	verbose bool
+
+	// flags replacement
+	maxLogMessageLen int
+	maxLogKeyLen     int
+
+	reportTimeout time.Duration
+
+	thriftConnectorFactory ConnectorFactory
+}
+
+func newThriftCollectorClient(opts Options, guid uint64, attributes map[string]string) *thriftCollectorClient {
+	reportTimeout := 60 * time.Second
+	if opts.ReportTimeout > 0 {
+		reportTimeout = opts.ReportTimeout
+	}
+
+	now := time.Now()
+	rec := &thriftCollectorClient{
+		auth: &lightstep_thrift.Auth{
+			AccessToken: thrift.StringPtr(opts.AccessToken),
+		},
+		attributes:             attributes,
+		startTime:              now,
+		maxReportingPeriod:     opts.ReportingPeriod,
+		verbose:                opts.Verbose,
+		collectorURL:           opts.Collector.URL(),
+		AccessToken:            opts.AccessToken,
+		maxLogMessageLen:       opts.MaxLogValueLen,
+		maxLogKeyLen:           opts.MaxLogKeyLen,
+		reportTimeout:          reportTimeout,
+		thriftConnectorFactory: opts.ConnFactory,
+		reporterID:             guid,
+	}
+	return rec
+}
+
+func (client *thriftCollectorClient) ConnectClient() (Connection, error) {
+	var conn Connection
+
+	if client.thriftConnectorFactory != nil {
+		uncheckedClient, transport, err := client.thriftConnectorFactory()
+		if err != nil {
+			return nil, err
+		}
+
+		thriftClient, ok := uncheckedClient.(lightstep_thrift.ReportingService)
+		if !ok {
+			return nil, fmt.Errorf("thrift connector factory did not provide valid client")
+		}
+
+		conn = transport
+		client.thriftClient = thriftClient
+	} else {
+		transport, err := thrift.NewTHttpPostClient(client.collectorURL, client.reportTimeout)
+		if err != nil {
+			return nil, err
+		}
+
+		conn = transport
+		client.thriftClient = lightstep_thrift.NewReportingServiceClientFactory(
+			transport,
+			thrift.NewTBinaryProtocolFactoryDefault(),
+		)
+	}
+	return conn, nil
+}
+
+func (*thriftCollectorClient) ShouldReconnect() bool {
+	return false
+}
+
+func (client *thriftCollectorClient) Report(_ context.Context, req reportRequest) (collectorResponse, error) {
+	if req.thriftRequest == nil {
+		return nil, fmt.Errorf("thriftRequest cannot be null")
+	}
+	resp, err := client.thriftClient.Report(client.auth, req.thriftRequest)
+	if err != nil {
+		return nil, err
+	}
+
+	return resp, err
+}
+
+func (client *thriftCollectorClient) Translate(_ context.Context, buffer *reportBuffer) (reportRequest, error) {
+	rawSpans := buffer.rawSpans
+	// Convert them to thrift.
+	recs := make([]*lightstep_thrift.SpanRecord, len(rawSpans))
+	// TODO: could pool lightstep_thrift.SpanRecords
+	for i, raw := range rawSpans {
+		var joinIds []*lightstep_thrift.TraceJoinId
+		var attributes []*lightstep_thrift.KeyValue
+		for key, value := range raw.Tags {
+			// Note: the gRPC tracer uses Sprintf("%#v") for non-scalar non-string
+			// values, differs from the treatment here:
+			if strings.HasPrefix(key, "join:") {
+				joinIds = append(joinIds, &lightstep_thrift.TraceJoinId{TraceKey: key, Value: fmt.Sprint(value)})
+			} else {
+				attributes = append(attributes, &lightstep_thrift.KeyValue{Key: key, Value: fmt.Sprint(value)})
+			}
+		}
+		logs := make([]*lightstep_thrift.LogRecord, len(raw.Logs))
+		for j, log := range raw.Logs {
+			thriftLogRecord := &lightstep_thrift.LogRecord{
+				TimestampMicros: thrift.Int64Ptr(log.Timestamp.UnixNano() / 1000),
+			}
+			// In the deprecated thrift case, we can reuse a single "field"
+			// encoder across all of the N log fields.
+			lfe := thriftLogFieldEncoder{thriftLogRecord, client}
+			for _, f := range log.Fields {
+				f.Marshal(&lfe)
+			}
+			logs[j] = thriftLogRecord
+		}
+
+		// TODO implement baggage
+		if raw.ParentSpanID != 0 {
+			attributes = append(attributes, &lightstep_thrift.KeyValue{Key: ParentSpanGUIDKey,
+				Value: strconv.FormatUint(raw.ParentSpanID, 16)})
+		}
+
+		recs[i] = &lightstep_thrift.SpanRecord{
+			SpanGuid:       thrift.StringPtr(strconv.FormatUint(raw.Context.SpanID, 16)),
+			TraceGuid:      thrift.StringPtr(strconv.FormatUint(raw.Context.TraceID, 16)),
+			SpanName:       thrift.StringPtr(raw.Operation),
+			JoinIds:        joinIds,
+			OldestMicros:   thrift.Int64Ptr(raw.Start.UnixNano() / 1000),
+			YoungestMicros: thrift.Int64Ptr(raw.Start.Add(raw.Duration).UnixNano() / 1000),
+			Attributes:     attributes,
+			LogRecords:     logs,
+		}
+	}
+
+	metrics := lightstep_thrift.Metrics{
+		Counts: []*lightstep_thrift.MetricsSample{
+			&lightstep_thrift.MetricsSample{
+				Name:       "spans.dropped",
+				Int64Value: &buffer.droppedSpanCount,
+			},
+		},
+	}
+
+	req := &lightstep_thrift.ReportRequest{
+		OldestMicros:    thrift.Int64Ptr(buffer.reportEnd.UnixNano() / 1000),
+		YoungestMicros:  thrift.Int64Ptr(buffer.reportStart.UnixNano() / 1000),
+		Runtime:         client.thriftRuntime(),
+		SpanRecords:     recs,
+		InternalMetrics: &metrics,
+	}
+	return reportRequest{
+		thriftRequest: req,
+	}, nil
+}
+
+// caller must hold r.lock
+func (client *thriftCollectorClient) thriftRuntime() *lightstep_thrift.Runtime {
+	guid := strconv.FormatUint(client.reporterID, 10)
+	runtimeAttrs := []*lightstep_thrift.KeyValue{}
+	for k, v := range client.attributes {
+		runtimeAttrs = append(runtimeAttrs, &lightstep_thrift.KeyValue{Key: k, Value: v})
+	}
+	return &lightstep_thrift.Runtime{
+		StartMicros: thrift.Int64Ptr(client.startTime.UnixNano() / 1000),
+		Attrs:       runtimeAttrs,
+		Guid:        &guid,
+	}
+}

vendor/github.com/lightstep/lightstep-tracer-go/collectorpb/collector.go

+package collectorpb
+
+func (res *ReportResponse) Disable() bool {
+	for _, command := range res.GetCommands() {
+		if command.Disable {
+			return true
+		}
+	}
+	return false
+}

vendor/github.com/lightstep/lightstep-tracer-go/event_handlers.go

+package lightstep
+
+import (
+	"log"
+	"sync"
+	"sync/atomic"
+)
+
+func init() {
+	SetGlobalEventHandler(NewEventLogOneError())
+}
+
+var eventHandler atomic.Value
+
+// An EventHandler can be registered with SetGlobalEventHandler to
+type EventHandler func(Event)
+
+// emitEvent is a thread-safe function for emiting tracer events.
+func emitEvent(event Event) {
+	handler := eventHandler.Load().(EventHandler)
+	handler(event)
+}
+
+// SetGlobalEventHandler sets a global handler to receive tracer events as they occur. Events
+// may be emitted by the tracer, or by calls to static functions in this package.
+// It is suggested that you set your EventHandler before starting your tracer,
+// but it is safe to set a new handler at any time. Setting a new handler removes
+// the previous one.
+//
+// The EventHandler is called synchronously – do not block in your handler as it
+// may interfere with the tracer. If no EventHandler handler is set, a
+// LogOnceOnError handler is set by default.
+//
+// NOTE: Event handling is for reporting purposes only. It is not intended as a
+// mechanism for controling or restarting the tracer. Connection issues, retry
+// logic, and other transient errors are handled internally by the tracer.
+func SetGlobalEventHandler(handler EventHandler) {
+	eventHandler.Store(handler)
+}
+
+/*
+	SetGlobalEventHandler Handlers
+*/
+
+// NewEventLogger logs events using the standard go logger.
+func NewEventLogger() EventHandler {
+	return logOnEvent
+}
+
+func logOnEvent(event Event) {
+	switch event := event.(type) {
+	case ErrorEvent:
+		log.Println("LS Tracer error: ", event)
+	default:
+		log.Println("LS Tracer event: ", event)
+	}
+}
+
+// NewEventLogOneError logs the first error event that occurs.
+func NewEventLogOneError() EventHandler {
+	logger := logOneError{}
+	return logger.OnEvent
+}
+
+type logOneError struct {
+	sync.Once
+}
+
+func (l *logOneError) OnEvent(event Event) {
+	switch event := event.(type) {
+	case ErrorEvent:
+		l.Once.Do(func() {
+			log.Printf("LS Tracer error: (%s). NOTE: Set the SetGlobalEventHandler handler to log events.\n", event.Error())
+		})
+	}
+}
+
+// NewEventChannel returns an SetGlobalEventHandler callback handler, and a channel that
+// produces the errors. When the channel buffer is full, subsequent errors will
+// be dropped. A buffer size of less than one is incorrect, and will be adjusted
+// to a buffer size of one.
+func NewEventChannel(buffer int) (EventHandler, <-chan Event) {
+	if buffer < 1 {
+		buffer = 1
+	}
+
+	eventChan := make(chan Event, buffer)
+
+	handler := func(event Event) {
+		select {
+		case eventChan <- event:
+		default:
+		}
+	}
+
+	return handler, eventChan
+}

vendor/github.com/lightstep/lightstep-tracer-go/events.go

+package lightstep
+
+import (
+	"errors"
+	"fmt"
+	"reflect"
+	"time"
+
+	opentracing "github.com/opentracing/opentracing-go"
+)
+
+// An Event is emitted by the LightStep tracer as a reporting mechanism. They are
+// handled by registering an EventHandler callback via SetGlobalEventHandler. The
+// emitted events may be cast to specific event types in order access additional
+// information.
+//
+// NOTE: To ensure that events can be accurately identified, each event type contains
+// a sentinel method matching the name of the type. This method is a no-op, it is
+// only used for type coersion.
+type Event interface {
+	Event()
+	String() string
+}
+
+// The ErrorEvent type can be used to filter events. The `Err` method
+// retuns the underlying error.
+type ErrorEvent interface {
+	Event
+	error
+	Err() error
+}
+
+// EventStartError occurs if the Options passed to NewTracer are invalid, and
+// the Tracer has failed to start.
+type EventStartError interface {
+	ErrorEvent
+	EventStartError()
+}
+
+type eventStartError struct {
+	err error
+}
+
+func newEventStartError(err error) *eventStartError {
+	return &eventStartError{err: err}
+}
+
+func (*eventStartError) Event()           {}
+func (*eventStartError) EventStartError() {}
+
+func (e *eventStartError) String() string {
+	return e.err.Error()
+}
+
+func (e *eventStartError) Error() string {
+	return e.err.Error()
+}
+
+func (e *eventStartError) Err() error {
+	return e.err
+}
+
+// EventFlushErrorState lists the possible causes for a flush to fail.
+type EventFlushErrorState string
+
+// Constant strings corresponding to flush errors
+const (
+	FlushErrorTracerClosed   EventFlushErrorState = "flush failed, the tracer is closed."
+	FlushErrorTracerDisabled EventFlushErrorState = "flush failed, the tracer is disabled."
+	FlushErrorTransport      EventFlushErrorState = "flush failed, could not send report to Collector"
+	FlushErrorReport         EventFlushErrorState = "flush failed, report contained errors"
+	FlushErrorTranslate      EventFlushErrorState = "flush failed, could not translate report"
+)
+
+var (
+	errFlushFailedTracerClosed = errors.New(string(FlushErrorTracerClosed))
+)
+
+// EventFlushError occurs when a flush fails to send. Call the `State` method to
+// determine the type of error.
+type EventFlushError interface {
+	ErrorEvent
+	EventFlushError()
+	State() EventFlushErrorState
+}
+
+type eventFlushError struct {
+	err   error
+	state EventFlushErrorState
+}
+
+func newEventFlushError(err error, state EventFlushErrorState) *eventFlushError {
+	return &eventFlushError{err: err, state: state}
+}
+
+func (*eventFlushError) Event()           {}
+func (*eventFlushError) EventFlushError() {}
+
+func (e *eventFlushError) State() EventFlushErrorState {
+	return e.state
+}
+
+func (e *eventFlushError) String() string {
+	return e.err.Error()
+}
+
+func (e *eventFlushError) Error() string {
+	return e.err.Error()
+}
+
+func (e *eventFlushError) Err() error {
+	return e.err
+}
+
+// EventConnectionError occurs when the tracer fails to maintain it's connection
+// with the Collector.
+type EventConnectionError interface {
+	ErrorEvent
+	EventConnectionError()
+}
+
+type eventConnectionError struct {
+	err error
+}
+
+func newEventConnectionError(err error) *eventConnectionError {
+	return &eventConnectionError{err: err}
+}
+
+func (*eventConnectionError) Event()                {}
+func (*eventConnectionError) EventConnectionError() {}
+
+func (e *eventConnectionError) String() string {
+	return e.err.Error()
+}
+
+func (e *eventConnectionError) Error() string {
+	return e.err.Error()
+}
+
+func (e *eventConnectionError) Err() error {
+	return e.err
+}
+
+// EventStatusReport occurs on every successful flush. It contains all metrics
+// collected since the previous succesful flush.
+type EventStatusReport interface {
+	Event
+	EventStatusReport()
+	StartTime() time.Time
+	FinishTime() time.Time
+	Duration() time.Duration
+	SentSpans() int
+	DroppedSpans() int
+	EncodingErrors() int
+}
+
+type eventStatusReport struct {
+	startTime      time.Time
+	finishTime     time.Time
+	sentSpans      int
+	droppedSpans   int
+	encodingErrors int
+}
+
+func newEventStatusReport(
+	startTime, finishTime time.Time,
+	sentSpans, droppedSpans, encodingErrors int,
+) *eventStatusReport {
+	return &eventStatusReport{
+		startTime:      startTime,
+		finishTime:     finishTime,
+		sentSpans:      sentSpans,
+		droppedSpans:   droppedSpans,
+		encodingErrors: encodingErrors,
+	}
+}
+
+func (*eventStatusReport) Event() {}
+
+func (*eventStatusReport) EventStatusReport() {}
+
+func (s *eventStatusReport) SetSentSpans(sent int) {
+	s.sentSpans = sent
+}
+
+func (s *eventStatusReport) StartTime() time.Time {
+	return s.startTime
+}
+
+func (s *eventStatusReport) FinishTime() time.Time {
+	return s.finishTime
+}
+
+func (s *eventStatusReport) Duration() time.Duration {
+	return s.finishTime.Sub(s.startTime)
+}
+
+func (s *eventStatusReport) SentSpans() int {
+	return s.sentSpans
+}
+
+func (s *eventStatusReport) DroppedSpans() int {
+	return s.droppedSpans
+}
+
+func (s *eventStatusReport) EncodingErrors() int {
+	return s.encodingErrors
+}
+
+func (s *eventStatusReport) String() string {
+	return fmt.Sprint(
+		"STATUS REPORT start: ", s.startTime,
+		", end: ", s.finishTime,
+		", dropped spans: ", s.droppedSpans,
+		", encoding errors: ", s.encodingErrors,
+	)
+}
+
+// EventUnsupportedTracer occurs when a tracer being passed to a helper function
+// fails to typecast as a LightStep tracer.
+type EventUnsupportedTracer interface {
+	ErrorEvent
+	EventUnsupportedTracer()
+	Tracer() opentracing.Tracer
+}
+
+type eventUnsupportedTracer struct {
+	tracer opentracing.Tracer
+	err    error
+}
+
+func newEventUnsupportedTracer(tracer opentracing.Tracer) EventUnsupportedTracer {
+	return &eventUnsupportedTracer{
+		tracer: tracer,
+		err:    fmt.Errorf("unsupported tracer type: %v", reflect.TypeOf(tracer)),
+	}
+}
+
+func (e *eventUnsupportedTracer) Event()                  {}
+func (e *eventUnsupportedTracer) EventUnsupportedTracer() {}
+
+func (e *eventUnsupportedTracer) Tracer() opentracing.Tracer {
+	return e.tracer
+}
+
+func (e *eventUnsupportedTracer) String() string {
+	return e.err.Error()
+}
+
+func (e *eventUnsupportedTracer) Error() string {
+	return e.err.Error()
+}
+
+func (e *eventUnsupportedTracer) Err() error {
+	return e.err
+}
+
+// EventUnsupportedValue occurs when a tracer encounters an unserializable tag
+// or log field.
+type EventUnsupportedValue interface {
+	ErrorEvent
+	EventUnsupportedValue()
+	Key() string
+	Value() interface{}
+}
+
+type eventUnsupportedValue struct {
+	key   string
+	value interface{}
+	err   error
+}
+
+func newEventUnsupportedValue(key string, value interface{}, err error) EventUnsupportedValue {
+	if err == nil {
+		err = fmt.Errorf(
+			"value `%v` of type `%T` for key `%s` is an unsupported type",
+			value, value, key,
+		)
+	}
+	return &eventUnsupportedValue{
+		key:   key,
+		value: value,
+		err:   err,
+	}
+}
+
+func (e *eventUnsupportedValue) Event()                 {}
+func (e *eventUnsupportedValue) EventUnsupportedValue() {}
+
+func (e *eventUnsupportedValue) Key() string {
+	return e.key
+}
+
+func (e *eventUnsupportedValue) Value() interface{} {
+	return e.value
+}
+
+func (e *eventUnsupportedValue) String() string {
+	return e.err.Error()
+}
+
+func (e *eventUnsupportedValue) Error() string {
+	return e.err.Error()
+}
+
+func (e *eventUnsupportedValue) Err() error {
+	return e.err
+}
+
+const tracerDisabled = "the tracer has been disabled"
+
+// EventTracerDisabled occurs when a tracer is disabled by either the user or
+// the collector.
+type EventTracerDisabled interface {
+	Event
+	EventTracerDisabled()
+}
+
+type eventTracerDisabled struct{}
+
+func newEventTracerDisabled() EventTracerDisabled {
+	return eventTracerDisabled{}
+}
+
+func (eventTracerDisabled) Event()               {}
+func (eventTracerDisabled) EventTracerDisabled() {}
+func (eventTracerDisabled) String() string {
+	return tracerDisabled
+}

vendor/github.com/lightstep/lightstep-tracer-go/lightstep/rand/locked_rand.go

+package rand
+
+import (
+	"math/rand"
+	"sync"
+)
+
+// LockedRand implements NumberGenerator and embeds Rand that is safe for concurrent use.
+type LockedRand struct {
+	lk sync.Mutex
+	r  *rand.Rand
+}
+
+// NewLockedRand creates a new LockedRand that implements all Rand functions that is safe
+// for concurrent use.
+func NewLockedRand(seed int64) *LockedRand {
+	return &LockedRand{
+		r: rand.New(rand.NewSource(seed)),
+	}
+}
+
+// Seed uses the provided seed value to initialize the generator to a deterministic state.
+// Seed should not be called concurrently with any other Rand method.
+func (lr *LockedRand) Seed(seed int64) {
+	lr.lk.Lock()
+	lr.r.Seed(seed)
+	lr.lk.Unlock()
+}
+
+// TwoInt63 generates 2 random int64 without locking twice.
+func (lr *LockedRand) TwoInt63() (n1, n2 int64) {
+	lr.lk.Lock()
+	n1 = lr.r.Int63()
+	n2 = lr.r.Int63()
+	lr.lk.Unlock()
+	return
+}
+
+// Int63 returns a non-negative pseudo-random 63-bit integer as an int64.
+func (lr *LockedRand) Int63() (n int64) {
+	lr.lk.Lock()
+	n = lr.r.Int63()
+	lr.lk.Unlock()
+	return
+}
+
+// Uint32 returns a pseudo-random 32-bit value as a uint32.
+func (lr *LockedRand) Uint32() (n uint32) {
+	lr.lk.Lock()
+	n = lr.r.Uint32()
+	lr.lk.Unlock()
+	return
+}
+
+// Uint64 returns a pseudo-random 64-bit value as a uint64.
+func (lr *LockedRand) Uint64() (n uint64) {
+	lr.lk.Lock()
+	n = lr.r.Uint64()
+	lr.lk.Unlock()
+	return
+}
+
+// Int31 returns a non-negative pseudo-random 31-bit integer as an int32.
+func (lr *LockedRand) Int31() (n int32) {
+	lr.lk.Lock()
+	n = lr.r.Int31()
+	lr.lk.Unlock()
+	return
+}
+
+// Int returns a non-negative pseudo-random int.
+func (lr *LockedRand) Int() (n int) {
+	lr.lk.Lock()
+	n = lr.r.Int()
+	lr.lk.Unlock()
+	return
+}
+
+// Int63n returns, as an int64, a non-negative pseudo-random number in [0,n).
+// It panics if n <= 0.
+func (lr *LockedRand) Int63n(n int64) (r int64) {
+	lr.lk.Lock()
+	r = lr.r.Int63n(n)
+	lr.lk.Unlock()
+	return
+}
+
+// Int31n returns, as an int32, a non-negative pseudo-random number in [0,n).
+// It panics if n <= 0.
+func (lr *LockedRand) Int31n(n int32) (r int32) {
+	lr.lk.Lock()
+	r = lr.r.Int31n(n)
+	lr.lk.Unlock()
+	return
+}
+
+// Intn returns, as an int, a non-negative pseudo-random number in [0,n).
+// It panics if n <= 0.
+func (lr *LockedRand) Intn(n int) (r int) {
+	lr.lk.Lock()
+	r = lr.r.Intn(n)
+	lr.lk.Unlock()
+	return
+}
+
+// Float64 returns, as a float64, a pseudo-random number in [0.0,1.0).
+func (lr *LockedRand) Float64() (n float64) {
+	lr.lk.Lock()
+	n = lr.r.Float64()
+	lr.lk.Unlock()
+	return
+}
+
+// Float32 returns, as a float32, a pseudo-random number in [0.0,1.0).
+func (lr *LockedRand) Float32() (n float32) {
+	lr.lk.Lock()
+	n = lr.r.Float32()
+	lr.lk.Unlock()
+	return
+}
+
+// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n).
+func (lr *LockedRand) Perm(n int) (r []int) {
+	lr.lk.Lock()
+	r = lr.r.Perm(n)
+	lr.lk.Unlock()
+	return
+}
+
+// Read generates len(p) random bytes and writes them into p. It
+// always returns len(p) and a nil error.
+// Read should not be called concurrently with any other Rand method.
+func (lr *LockedRand) Read(p []byte) (n int, err error) {
+	lr.lk.Lock()
+	n, err = lr.r.Read(p)
+	lr.lk.Unlock()
+	return
+}

vendor/github.com/lightstep/lightstep-tracer-go/lightstep/rand/num_gen.go

+package rand
+
+// NumberGenerator defines an interface to generate numbers.
+type NumberGenerator interface {
+	Int63() int64
+	TwoInt63() (int64, int64)
+}

vendor/github.com/lightstep/lightstep-tracer-go/lightstep/rand/pool.go

+package rand
+
+import (
+	"math/rand"
+	"sync/atomic"
+)
+
+// Pool represents a pool of random number generators.
+// To generate a random id, round robin through the source pool with atomic increment.
+// With more and more goroutines, Pool improves the performance of Random vs naive global random
+// mutex exponentially.
+// Try tests with 20000 goroutines and 500 calls to observe the difference
+type Pool struct {
+	sources []NumberGenerator
+	counter uint64 // used for round robin
+	size    uint64
+}
+
+// see bit twiddling hacks: https://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
+func nextNearestPow2uint64(v uint64) uint64 {
+	v--
+	v |= v >> 1
+	v |= v >> 2
+	v |= v >> 4
+	v |= v >> 8
+	v |= v >> 16
+	v |= v >> 32
+	v++
+	return v
+}
+
+// NewPool takes in a size and creates a pool of random id generators with size equal to next closest power of 2.
+// eg: NewPool(10) returns a pool with 2^4 = 16 random sources.
+func NewPool(seed int64, size uint64) *Pool {
+	groupsize := nextNearestPow2uint64(size)
+	pool := &Pool{
+		size:    groupsize,
+		sources: make([]NumberGenerator, groupsize),
+	}
+	// seed the pool
+	pool.seed(seed)
+	return pool
+}
+
+// seed initializes the pool using a randomized sequence with given seed.
+func (r *Pool) seed(seed int64) {
+	// init a random sequence to seed all sources
+	seedRan := rand.NewSource(seed)
+	for i := uint64(0); i < r.size; i++ {
+		r.sources[i] = NewLockedRand(seedRan.Int63())
+	}
+}
+
+// Pick returns a NumberGenerator from a pool of NumberGenerators
+func (r *Pool) Pick() NumberGenerator {
+	// use round robin with fast modulus of pow2 numbers
+	selection := atomic.AddUint64(&r.counter, 1) & (r.size - 1)
+	return r.sources[selection]
+}

vendor/github.com/lightstep/lightstep-tracer-go/lightstep_thrift/constants.go

+// Autogenerated by Thrift Compiler (0.9.2)
+// DO NOT EDIT UNLESS YOU ARE SURE THAT YOU KNOW WHAT YOU ARE DOING
+
+package lightstep_thrift
+
+import (
+	"bytes"
+	"fmt"
+	"github.com/lightstep/thrift/lib/go/thrift"
+)
+
+// (needed to ensure safety because of naive import list construction.)
+var _ = thrift.ZERO
+var _ = fmt.Printf
+var _ = bytes.Equal
+
+func init() {
+}

vendor/github.com/lightstep/lightstep-tracer-go/lightstep_thrift/reportingservice_methods.go

+package lightstep_thrift
+
+func (res *ReportResponse) Disable() bool {
+	for _, command := range res.GetCommands() {
+		if *command.Disable {
+			return true
+		}
+	}
+	return false
+}

vendor/github.com/lightstep/lightstep-tracer-go/lightsteppb/lightstep.pb.go

+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: lightstep.proto
+
+/*
+Package lightsteppb is a generated protocol buffer package.
+
+It is generated from these files:
+	lightstep.proto
+
+It has these top-level messages:
+	BinaryCarrier
+	BasicTracerCarrier
+*/
+package lightsteppb
+
+import proto "github.com/golang/protobuf/proto"
+import fmt "fmt"
+import math "math"
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
+
+// The standard carrier for binary context propagation into LightStep.
+type BinaryCarrier struct {
+	// "text_ctx" was deprecated following lightstep-tracer-cpp-0.36
+	DeprecatedTextCtx [][]byte `protobuf:"bytes,1,rep,name=deprecated_text_ctx,json=deprecatedTextCtx,proto3" json:"deprecated_text_ctx,omitempty"`
+	// The Opentracing "basictracer" proto.
+	BasicCtx *BasicTracerCarrier `protobuf:"bytes,2,opt,name=basic_ctx,json=basicCtx" json:"basic_ctx,omitempty"`
+}
+
+func (m *BinaryCarrier) Reset()                    { *m = BinaryCarrier{} }
+func (m *BinaryCarrier) String() string            { return proto.CompactTextString(m) }
+func (*BinaryCarrier) ProtoMessage()               {}
+func (*BinaryCarrier) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
+
+func (m *BinaryCarrier) GetDeprecatedTextCtx() [][]byte {
+	if m != nil {
+		return m.DeprecatedTextCtx
+	}
+	return nil
+}
+
+func (m *BinaryCarrier) GetBasicCtx() *BasicTracerCarrier {
+	if m != nil {
+		return m.BasicCtx
+	}
+	return nil
+}
+
+// Copy of https://github.com/opentracing/basictracer-go/blob/master/wire/wire.proto
+type BasicTracerCarrier struct {
+	TraceId      uint64            `protobuf:"fixed64,1,opt,name=trace_id,json=traceId" json:"trace_id,omitempty"`
+	SpanId       uint64            `protobuf:"fixed64,2,opt,name=span_id,json=spanId" json:"span_id,omitempty"`
+	Sampled      bool              `protobuf:"varint,3,opt,name=sampled" json:"sampled,omitempty"`
+	BaggageItems map[string]string `protobuf:"bytes,4,rep,name=baggage_items,json=baggageItems" json:"baggage_items,omitempty" protobuf_key:"bytes,1,opt,name=key" protobuf_val:"bytes,2,opt,name=value"`
+}
+
+func (m *BasicTracerCarrier) Reset()                    { *m = BasicTracerCarrier{} }
+func (m *BasicTracerCarrier) String() string            { return proto.CompactTextString(m) }
+func (*BasicTracerCarrier) ProtoMessage()               {}
+func (*BasicTracerCarrier) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{1} }
+
+func (m *BasicTracerCarrier) GetTraceId() uint64 {
+	if m != nil {
+		return m.TraceId
+	}
+	return 0
+}
+
+func (m *BasicTracerCarrier) GetSpanId() uint64 {
+	if m != nil {
+		return m.SpanId
+	}
+	return 0
+}
+
+func (m *BasicTracerCarrier) GetSampled() bool {
+	if m != nil {
+		return m.Sampled
+	}
+	return false
+}
+
+func (m *BasicTracerCarrier) GetBaggageItems() map[string]string {
+	if m != nil {
+		return m.BaggageItems
+	}
+	return nil
+}
+
+func init() {
+	proto.RegisterType((*BinaryCarrier)(nil), "lightstep.BinaryCarrier")
+	proto.RegisterType((*BasicTracerCarrier)(nil), "lightstep.BasicTracerCarrier")
+}
+
+func init() { proto.RegisterFile("lightstep.proto", fileDescriptor0) }
+
+var fileDescriptor0 = []byte{
+	// 290 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x7c, 0x91, 0xcf, 0x4b, 0xf3, 0x30,
+	0x18, 0xc7, 0xc9, 0xfa, 0xbe, 0xdb, 0xfa, 0x6c, 0x43, 0x17, 0x05, 0xab, 0x20, 0x94, 0x9d, 0x7a,
+	0xaa, 0x30, 0x2f, 0xb2, 0x8b, 0xd0, 0xe1, 0x61, 0xd7, 0xb0, 0x93, 0x97, 0x92, 0x36, 0x0f, 0x35,
+	0xb8, 0x75, 0x21, 0x7d, 0x94, 0x16, 0xff, 0x72, 0x6f, 0x92, 0x4c, 0x37, 0x61, 0xe0, 0x2d, 0xdf,
+	0x1f, 0x0f, 0xdf, 0x0f, 0x04, 0xce, 0x36, 0xba, 0x7a, 0xa1, 0x86, 0xd0, 0xa4, 0xc6, 0xee, 0x68,
+	0xc7, 0xc3, 0x83, 0x31, 0xfb, 0x80, 0x49, 0xa6, 0x6b, 0x69, 0xbb, 0xa5, 0xb4, 0x56, 0xa3, 0xe5,
+	0x29, 0x5c, 0x28, 0x34, 0x16, 0x4b, 0x49, 0xa8, 0x72, 0xc2, 0x96, 0xf2, 0x92, 0xda, 0x88, 0xc5,
+	0x41, 0x32, 0x16, 0xd3, 0x63, 0xb4, 0xc6, 0x96, 0x96, 0xd4, 0xf2, 0x05, 0x84, 0x85, 0x6c, 0x74,
+	0xe9, 0x5b, 0xbd, 0x98, 0x25, 0xa3, 0xf9, 0x6d, 0x7a, 0x1c, 0xcc, 0x5c, 0xb6, 0xb6, 0xb2, 0x44,
+	0xfb, 0xbd, 0x20, 0x86, 0xbe, 0xbf, 0xa4, 0x76, 0xf6, 0xc9, 0x80, 0x9f, 0x16, 0xf8, 0x35, 0x0c,
+	0xc9, 0x19, 0xb9, 0x56, 0x11, 0x8b, 0x59, 0xd2, 0x17, 0x03, 0xaf, 0x57, 0x8a, 0x5f, 0xc1, 0xa0,
+	0x31, 0xb2, 0x76, 0x49, 0xcf, 0x27, 0x7d, 0x27, 0x57, 0x8a, 0x47, 0x30, 0x68, 0xe4, 0xd6, 0x6c,
+	0x50, 0x45, 0x41, 0xcc, 0x92, 0xa1, 0xf8, 0x91, 0x7c, 0x0d, 0x93, 0x42, 0x56, 0x95, 0xac, 0x30,
+	0xd7, 0x84, 0xdb, 0x26, 0xfa, 0x17, 0x07, 0xc9, 0x68, 0x7e, 0xf7, 0x27, 0x64, 0x9a, 0xed, 0x4f,
+	0x56, 0xee, 0xe2, 0xa9, 0x26, 0xdb, 0x89, 0x71, 0xf1, 0xcb, 0xba, 0x79, 0x84, 0xe9, 0x49, 0x85,
+	0x9f, 0x43, 0xf0, 0x8a, 0x9d, 0x67, 0x0e, 0x85, 0x7b, 0xf2, 0x4b, 0xf8, 0xff, 0x2e, 0x37, 0x6f,
+	0xe8, 0x69, 0x43, 0xb1, 0x17, 0x8b, 0xde, 0x03, 0xcb, 0x26, 0xcf, 0xa3, 0x03, 0x80, 0x29, 0x8a,
+	0xbe, 0xff, 0x99, 0xfb, 0xaf, 0x00, 0x00, 0x00, 0xff, 0xff, 0x7a, 0xf7, 0xd5, 0xf5, 0xac, 0x01,
+	0x00, 0x00,
+}

vendor/github.com/lightstep/lightstep-tracer-go/tag_version.sh

+#!/bin/sh
+
+VERSION=$(cat ./VERSION)
+
+cat > version.go <<EOF
+package lightstep
+
+// TracerVersionValue provides the current version of the lightstep-tracer-go release
+const TracerVersionValue = "$VERSION"
+EOF

vendor/github.com/lightstep/lightstep-tracer-go/version.go

+package lightstep
+
+// TracerVersionValue provides the current version of the lightstep-tracer-go release
+const TracerVersionValue = "0.15.6"

vendor/github.com/lightstep/thrift/NOTICE

+Apache Thrift
+Copyright 2006-2010 The Apache Software Foundation.
+
+This product includes software developed at
+The Apache Software Foundation (http://www.apache.org/).
\ No newline at end of file