Add ocagent exporter

ocagent allows users to send traces out of VK to a "standard"  external forwarder
(standard as in this is a format/protocol defined in the opencensus project).

This allows uers to implement metrics for whatever backend they want
without having to add it into VK directly.

vendor/contrib.go.opencensus.io/exporter/ocagent/LICENSE

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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vendor/contrib.go.opencensus.io/exporter/ocagent/common.go

@@ -0,0 +1,38 @@
+// Copyright 2018, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ocagent
+
+import (
+	"math/rand"
+	"time"
+)
+
+var randSrc = rand.New(rand.NewSource(time.Now().UnixNano()))
+
+// retries function fn upto n times, if fn returns an error lest it returns nil early.
+// It applies exponential backoff in units of (1<<n) + jitter microsends.
+func nTriesWithExponentialBackoff(nTries int64, timeBaseUnit time.Duration, fn func() error) (err error) {
+	for i := int64(0); i < nTries; i++ {
+		err = fn()
+		if err == nil {
+			return nil
+		}
+		// Backoff for a time period with a pseudo-random jitter
+		jitter := time.Duration(randSrc.Float64()*100) * time.Microsecond
+		ts := jitter + ((1 << uint64(i)) * timeBaseUnit)
+		<-time.After(ts)
+	}
+	return err
+}

vendor/contrib.go.opencensus.io/exporter/ocagent/connection.go

@@ -0,0 +1,94 @@
+// Copyright 2018, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ocagent
+
+import (
+	"math/rand"
+	"sync/atomic"
+	"time"
+)
+
+const (
+	sDisconnected int32 = 5 + iota
+	sConnected
+)
+
+func (ae *Exporter) setStateDisconnected() {
+	atomic.StoreInt32(&ae.connectionState, sDisconnected)
+	ae.disconnectedCh <- true
+}
+
+func (ae *Exporter) setStateConnected() {
+	atomic.StoreInt32(&ae.connectionState, sConnected)
+}
+
+func (ae *Exporter) connected() bool {
+	return atomic.LoadInt32(&ae.connectionState) == sConnected
+}
+
+const defaultConnReattemptPeriod = 10 * time.Second
+
+func (ae *Exporter) indefiniteBackgroundConnection() error {
+	defer func() {
+		ae.backgroundConnectionDoneCh <- true
+	}()
+
+	connReattemptPeriod := ae.reconnectionPeriod
+	if connReattemptPeriod <= 0 {
+		connReattemptPeriod = defaultConnReattemptPeriod
+	}
+
+	// No strong seeding required, nano time can
+	// already help with pseudo uniqueness.
+	rng := rand.New(rand.NewSource(time.Now().UnixNano() + rand.Int63n(1024)))
+
+	// maxJitter: 1 + (70% of the connectionReattemptPeriod)
+	maxJitter := int64(1 + 0.7*float64(connReattemptPeriod))
+
+	for {
+		// Otherwise these will be the normal scenarios to enable
+		// reconnections if we trip out.
+		// 1. If we've stopped, return entirely
+		// 2. Otherwise block until we are disconnected, and
+		//    then retry connecting
+		select {
+		case <-ae.stopCh:
+			return errStopped
+
+		case <-ae.disconnectedCh:
+			// Normal scenario that we'll wait for
+		}
+
+		if err := ae.connect(); err == nil {
+			ae.setStateConnected()
+		} else {
+			ae.setStateDisconnected()
+		}
+
+		// Apply some jitter to avoid lockstep retrials of other
+		// agent-exporters. Lockstep retrials could result in an
+		// innocent DDOS, by clogging the machine's resources and network.
+		jitter := time.Duration(rng.Int63n(maxJitter))
+		<-time.After(connReattemptPeriod + jitter)
+	}
+}
+
+func (ae *Exporter) connect() error {
+	cc, err := ae.dialToAgent()
+	if err != nil {
+		return err
+	}
+	return ae.enableConnectionStreams(cc)
+}

vendor/contrib.go.opencensus.io/exporter/ocagent/nodeinfo.go

@@ -0,0 +1,41 @@
+// Copyright 2018, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ocagent
+
+import (
+	"os"
+
+	commonpb "github.com/census-instrumentation/opencensus-proto/gen-go/agent/common/v1"
+	"go.opencensus.io"
+)
+
+func createNodeInfo(nodeName string) *commonpb.Node {
+	return &commonpb.Node{
+		Identifier: &commonpb.ProcessIdentifier{
+			HostName:       os.Getenv("HOSTNAME"),
+			Pid:            uint32(os.Getpid()),
+			StartTimestamp: timeToTimestamp(startTime),
+		},
+		LibraryInfo: &commonpb.LibraryInfo{
+			Language:           commonpb.LibraryInfo_GO_LANG,
+			ExporterVersion:    Version,
+			CoreLibraryVersion: opencensus.Version(),
+		},
+		ServiceInfo: &commonpb.ServiceInfo{
+			Name: nodeName,
+		},
+		Attributes: make(map[string]string),
+	}
+}

vendor/contrib.go.opencensus.io/exporter/ocagent/ocagent.go

@@ -0,0 +1,320 @@
+// Copyright 2018, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ocagent
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"google.golang.org/api/support/bundler"
+	"google.golang.org/grpc"
+
+	"go.opencensus.io/trace"
+
+	agentcommonpb "github.com/census-instrumentation/opencensus-proto/gen-go/agent/common/v1"
+	agenttracepb "github.com/census-instrumentation/opencensus-proto/gen-go/agent/trace/v1"
+	tracepb "github.com/census-instrumentation/opencensus-proto/gen-go/trace/v1"
+)
+
+var startupMu sync.Mutex
+var startTime time.Time
+
+func init() {
+	startupMu.Lock()
+	startTime = time.Now()
+	startupMu.Unlock()
+}
+
+var _ trace.Exporter = (*Exporter)(nil)
+
+type Exporter struct {
+	connectionState int32
+
+	// mu protects the non-atomic and non-channel variables
+	mu                 sync.RWMutex
+	started            bool
+	stopped            bool
+	agentAddress       string
+	serviceName        string
+	canDialInsecure    bool
+	traceSvcClient     agenttracepb.TraceServiceClient
+	traceExporter      agenttracepb.TraceService_ExportClient
+	nodeInfo           *agentcommonpb.Node
+	grpcClientConn     *grpc.ClientConn
+	reconnectionPeriod time.Duration
+
+	startOnce      sync.Once
+	stopCh         chan bool
+	disconnectedCh chan bool
+
+	backgroundConnectionDoneCh chan bool
+
+	traceBundler *bundler.Bundler
+}
+
+func NewExporter(opts ...ExporterOption) (*Exporter, error) {
+	exp, err := NewUnstartedExporter(opts...)
+	if err != nil {
+		return nil, err
+	}
+	if err := exp.Start(); err != nil {
+		return nil, err
+	}
+	return exp, nil
+}
+
+const spanDataBufferSize = 300
+
+func NewUnstartedExporter(opts ...ExporterOption) (*Exporter, error) {
+	e := new(Exporter)
+	for _, opt := range opts {
+		opt.withExporter(e)
+	}
+	traceBundler := bundler.NewBundler((*trace.SpanData)(nil), func(bundle interface{}) {
+		e.uploadTraces(bundle.([]*trace.SpanData))
+	})
+	traceBundler.DelayThreshold = 2 * time.Second
+	traceBundler.BundleCountThreshold = spanDataBufferSize
+	e.traceBundler = traceBundler
+	e.nodeInfo = createNodeInfo(e.serviceName)
+
+	return e, nil
+}
+
+const (
+	maxInitialConfigRetries = 10
+	maxInitialTracesRetries = 10
+)
+
+var (
+	errAlreadyStarted = errors.New("already started")
+	errStopped        = errors.New("stopped")
+)
+
+// Start dials to the agent, establishing a connection to it. It also
+// initiates the Config and Trace services by sending over the initial
+// messages that consist of the node identifier. Start invokes a background
+// connector that will reattempt connections to the agent periodically
+// if the connection dies.
+func (ae *Exporter) Start() error {
+	var err = errAlreadyStarted
+	ae.startOnce.Do(func() {
+		ae.mu.Lock()
+		defer ae.mu.Unlock()
+
+		ae.started = true
+		ae.disconnectedCh = make(chan bool, 1)
+		ae.stopCh = make(chan bool)
+		ae.backgroundConnectionDoneCh = make(chan bool)
+
+		ae.setStateDisconnected()
+		go ae.indefiniteBackgroundConnection()
+
+		err = nil
+	})
+
+	return err
+}
+
+func (ae *Exporter) prepareAgentAddress() string {
+	if ae.agentAddress != "" {
+		return ae.agentAddress
+	}
+	return fmt.Sprintf("%s:%d", DefaultAgentHost, DefaultAgentPort)
+}
+
+func (ae *Exporter) enableConnectionStreams(cc *grpc.ClientConn) error {
+	ae.mu.RLock()
+	started := ae.started
+	nodeInfo := ae.nodeInfo
+	ae.mu.RUnlock()
+
+	if !started {
+		return errNotStarted
+	}
+
+	ae.mu.Lock()
+	// If the previous clientConn was non-nil, close it
+	if ae.grpcClientConn != nil {
+		_ = ae.grpcClientConn.Close()
+	}
+	ae.grpcClientConn = cc
+	ae.mu.Unlock()
+
+	// Initiate the trace service by sending over node identifier info.
+	traceSvcClient := agenttracepb.NewTraceServiceClient(cc)
+	traceExporter, err := traceSvcClient.Export(context.Background())
+	if err != nil {
+		return fmt.Errorf("Exporter.Start:: TraceServiceClient: %v", err)
+	}
+
+	firstTraceMessage := &agenttracepb.ExportTraceServiceRequest{Node: nodeInfo}
+	if err := traceExporter.Send(firstTraceMessage); err != nil {
+		return fmt.Errorf("Exporter.Start:: Failed to initiate the Config service: %v", err)
+	}
+	ae.traceExporter = traceExporter
+
+	// Initiate the config service by sending over node identifier info.
+	configStream, err := traceSvcClient.Config(context.Background())
+	if err != nil {
+		return fmt.Errorf("Exporter.Start:: ConfigStream: %v", err)
+	}
+	firstCfgMessage := &agenttracepb.CurrentLibraryConfig{Node: nodeInfo}
+	if err := configStream.Send(firstCfgMessage); err != nil {
+		return fmt.Errorf("Exporter.Start:: Failed to initiate the Config service: %v", err)
+	}
+
+	// In the background, handle trace configurations that are beamed down
+	// by the agent, but also reply to it with the applied configuration.
+	go ae.handleConfigStreaming(configStream)
+
+	return nil
+}
+
+func (ae *Exporter) dialToAgent() (*grpc.ClientConn, error) {
+	addr := ae.prepareAgentAddress()
+	var dialOpts []grpc.DialOption
+	if ae.canDialInsecure {
+		dialOpts = append(dialOpts, grpc.WithInsecure())
+	}
+	return grpc.Dial(addr, dialOpts...)
+}
+
+func (ae *Exporter) handleConfigStreaming(configStream agenttracepb.TraceService_ConfigClient) error {
+	// Note: We haven't yet implemented configuration sending so we
+	// should NOT be changing connection states within this function for now.
+	for {
+		recv, err := configStream.Recv()
+		if err != nil {
+			// TODO: Check if this is a transient error or exponential backoff-able.
+			return err
+		}
+		cfg := recv.Config
+		if cfg == nil {
+			continue
+		}
+
+		// Otherwise now apply the trace configuration sent down from the agent
+		if psamp := cfg.GetProbabilitySampler(); psamp != nil {
+			trace.ApplyConfig(trace.Config{DefaultSampler: trace.ProbabilitySampler(psamp.SamplingProbability)})
+		} else if csamp := cfg.GetConstantSampler(); csamp != nil {
+			alwaysSample := csamp.Decision == true
+			if alwaysSample {
+				trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})
+			} else {
+				trace.ApplyConfig(trace.Config{DefaultSampler: trace.NeverSample()})
+			}
+		} else { // TODO: Add the rate limiting sampler here
+		}
+
+		// Then finally send back to upstream the newly applied configuration
+		err = configStream.Send(&agenttracepb.CurrentLibraryConfig{Config: &tracepb.TraceConfig{Sampler: cfg.Sampler}})
+		if err != nil {
+			return err
+		}
+	}
+}
+
+var (
+	errNotStarted = errors.New("not started")
+)
+
+// Stop shuts down all the connections and resources
+// related to the exporter.
+func (ae *Exporter) Stop() error {
+	ae.mu.RLock()
+	cc := ae.grpcClientConn
+	started := ae.started
+	stopped := ae.stopped
+	ae.mu.RUnlock()
+
+	if !started {
+		return errNotStarted
+	}
+	if stopped {
+		// TODO: tell the user that we've already stopped, so perhaps a sentinel error?
+		return nil
+	}
+
+	ae.Flush()
+
+	// Now close the underlying gRPC connection.
+	var err error
+	if cc != nil {
+		err = cc.Close()
+	}
+
+	// At this point we can change the state variables: started and stopped
+	ae.mu.Lock()
+	ae.started = false
+	ae.stopped = true
+	ae.mu.Unlock()
+	close(ae.stopCh)
+
+	// Ensure that the backgroundConnector returns
+	<-ae.backgroundConnectionDoneCh
+
+	return err
+}
+
+func (ae *Exporter) ExportSpan(sd *trace.SpanData) {
+	if sd == nil {
+		return
+	}
+	_ = ae.traceBundler.Add(sd, 1)
+}
+
+func ocSpanDataToPbSpans(sdl []*trace.SpanData) []*tracepb.Span {
+	if len(sdl) == 0 {
+		return nil
+	}
+	protoSpans := make([]*tracepb.Span, 0, len(sdl))
+	for _, sd := range sdl {
+		if sd != nil {
+			protoSpans = append(protoSpans, ocSpanToProtoSpan(sd))
+		}
+	}
+	return protoSpans
+}
+
+func (ae *Exporter) uploadTraces(sdl []*trace.SpanData) {
+	select {
+	case <-ae.stopCh:
+		return
+
+	default:
+		if !ae.connected() {
+			return
+		}
+
+		protoSpans := ocSpanDataToPbSpans(sdl)
+		if len(protoSpans) == 0 {
+			return
+		}
+		err := ae.traceExporter.Send(&agenttracepb.ExportTraceServiceRequest{
+			Spans: protoSpans,
+		})
+		if err != nil {
+			ae.setStateDisconnected()
+		}
+	}
+}
+
+func (ae *Exporter) Flush() {
+	ae.traceBundler.Flush()
+}

vendor/contrib.go.opencensus.io/exporter/ocagent/options.go

@@ -0,0 +1,78 @@
+// Copyright 2018, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ocagent
+
+import "time"
+
+const (
+	DefaultAgentPort uint16 = 55678
+	DefaultAgentHost string = "localhost"
+)
+
+type ExporterOption interface {
+	withExporter(e *Exporter)
+}
+
+type insecureGrpcConnection int
+
+var _ ExporterOption = (*insecureGrpcConnection)(nil)
+
+func (igc *insecureGrpcConnection) withExporter(e *Exporter) {
+	e.canDialInsecure = true
+}
+
+// WithInsecure disables client transport security for the exporter's gRPC connection
+// just like grpc.WithInsecure() https://godoc.org/google.golang.org/grpc#WithInsecure
+// does. Note, by default, client security is required unless WithInsecure is used.
+func WithInsecure() ExporterOption { return new(insecureGrpcConnection) }
+
+type addressSetter string
+
+func (as addressSetter) withExporter(e *Exporter) {
+	e.agentAddress = string(as)
+}
+
+var _ ExporterOption = (*addressSetter)(nil)
+
+// WithAddress allows one to set the address that the exporter will
+// connect to the agent on. If unset, it will instead try to use
+// connect to DefaultAgentHost:DefaultAgentPort
+func WithAddress(addr string) ExporterOption {
+	return addressSetter(addr)
+}
+
+type serviceNameSetter string
+
+func (sns serviceNameSetter) withExporter(e *Exporter) {
+	e.serviceName = string(sns)
+}
+
+var _ ExporterOption = (*serviceNameSetter)(nil)
+
+// WithServiceName allows one to set/override the service name
+// that the exporter will report to the agent.
+func WithServiceName(serviceName string) ExporterOption {
+	return serviceNameSetter(serviceName)
+}
+
+type reconnectionPeriod time.Duration
+
+func (rp reconnectionPeriod) withExporter(e *Exporter) {
+	e.reconnectionPeriod = time.Duration(rp)
+}
+
+func WithReconnectionPeriod(rp time.Duration) ExporterOption {
+	return reconnectionPeriod(rp)
+}

vendor/contrib.go.opencensus.io/exporter/ocagent/transform_spans.go

@@ -0,0 +1,162 @@
+// Copyright 2018, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ocagent
+
+import (
+	"time"
+
+	"go.opencensus.io/trace"
+	"go.opencensus.io/trace/tracestate"
+
+	tracepb "github.com/census-instrumentation/opencensus-proto/gen-go/trace/v1"
+	"github.com/golang/protobuf/ptypes/timestamp"
+)
+
+func ocSpanToProtoSpan(sd *trace.SpanData) *tracepb.Span {
+	if sd == nil {
+		return nil
+	}
+	var namePtr *tracepb.TruncatableString
+	if sd.Name != "" {
+		namePtr = &tracepb.TruncatableString{Value: sd.Name}
+	}
+	return &tracepb.Span{
+		TraceId:      sd.TraceID[:],
+		SpanId:       sd.SpanID[:],
+		ParentSpanId: sd.ParentSpanID[:],
+		Status:       ocStatusToProtoStatus(sd.Status),
+		StartTime:    timeToTimestamp(sd.StartTime),
+		EndTime:      timeToTimestamp(sd.EndTime),
+		Links:        ocLinksToProtoLinks(sd.Links),
+		Kind:         ocSpanKindToProtoSpanKind(sd.SpanKind),
+		Name:         namePtr,
+		Attributes:   ocAttributesToProtoAttributes(sd.Attributes),
+		Tracestate:   ocTracestateToProtoTracestate(sd.Tracestate),
+	}
+}
+
+var blankStatus trace.Status
+
+func ocStatusToProtoStatus(status trace.Status) *tracepb.Status {
+	if status == blankStatus {
+		return nil
+	}
+	return &tracepb.Status{
+		Code:    status.Code,
+		Message: status.Message,
+	}
+}
+
+func ocLinksToProtoLinks(links []trace.Link) *tracepb.Span_Links {
+	if len(links) == 0 {
+		return nil
+	}
+
+	sl := make([]*tracepb.Span_Link, 0, len(links))
+	for _, ocLink := range links {
+		// This redefinition is necessary to prevent ocLink.*ID[:] copies
+		// being reused -- in short we need a new ocLink per iteration.
+		ocLink := ocLink
+
+		sl = append(sl, &tracepb.Span_Link{
+			TraceId: ocLink.TraceID[:],
+			SpanId:  ocLink.SpanID[:],
+			Type:    ocLinkTypeToProtoLinkType(ocLink.Type),
+		})
+	}
+
+	return &tracepb.Span_Links{
+		Link: sl,
+	}
+}
+
+func ocLinkTypeToProtoLinkType(oct trace.LinkType) tracepb.Span_Link_Type {
+	switch oct {
+	case trace.LinkTypeChild:
+		return tracepb.Span_Link_CHILD_LINKED_SPAN
+	case trace.LinkTypeParent:
+		return tracepb.Span_Link_PARENT_LINKED_SPAN
+	default:
+		return tracepb.Span_Link_TYPE_UNSPECIFIED
+	}
+}
+
+func ocAttributesToProtoAttributes(attrs map[string]interface{}) *tracepb.Span_Attributes {
+	if len(attrs) == 0 {
+		return nil
+	}
+	outMap := make(map[string]*tracepb.AttributeValue)
+	for k, v := range attrs {
+		switch v := v.(type) {
+		case bool:
+			outMap[k] = &tracepb.AttributeValue{Value: &tracepb.AttributeValue_BoolValue{BoolValue: v}}
+
+		case int:
+			outMap[k] = &tracepb.AttributeValue{Value: &tracepb.AttributeValue_IntValue{IntValue: int64(v)}}
+
+		case int64:
+			outMap[k] = &tracepb.AttributeValue{Value: &tracepb.AttributeValue_IntValue{IntValue: v}}
+
+		case string:
+			outMap[k] = &tracepb.AttributeValue{
+				Value: &tracepb.AttributeValue_StringValue{
+					StringValue: &tracepb.TruncatableString{Value: v},
+				},
+			}
+		}
+	}
+	return &tracepb.Span_Attributes{
+		AttributeMap: outMap,
+	}
+}
+
+func timeToTimestamp(t time.Time) *timestamp.Timestamp {
+	nanoTime := t.UnixNano()
+	return &timestamp.Timestamp{
+		Seconds: nanoTime / 1e9,
+		Nanos:   int32(nanoTime % 1e9),
+	}
+}
+
+func ocSpanKindToProtoSpanKind(kind int) tracepb.Span_SpanKind {
+	switch kind {
+	case trace.SpanKindClient:
+		return tracepb.Span_CLIENT
+	case trace.SpanKindServer:
+		return tracepb.Span_SERVER
+	default:
+		return tracepb.Span_SPAN_KIND_UNSPECIFIED
+	}
+}
+
+func ocTracestateToProtoTracestate(ts *tracestate.Tracestate) *tracepb.Span_Tracestate {
+	if ts == nil {
+		return nil
+	}
+	return &tracepb.Span_Tracestate{
+		Entries: ocTracestateEntriesToProtoTracestateEntries(ts.Entries()),
+	}
+}
+
+func ocTracestateEntriesToProtoTracestateEntries(entries []tracestate.Entry) []*tracepb.Span_Tracestate_Entry {
+	protoEntries := make([]*tracepb.Span_Tracestate_Entry, 0, len(entries))
+	for _, entry := range entries {
+		protoEntries = append(protoEntries, &tracepb.Span_Tracestate_Entry{
+			Key:   entry.Key,
+			Value: entry.Value,
+		})
+	}
+	return protoEntries
+}

vendor/contrib.go.opencensus.io/exporter/ocagent/version.go

@@ -0,0 +1,17 @@
+// Copyright 2018, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ocagent
+
+const Version = "0.0.1"