add opencensus tracing bridge (open-telemetry#1305)

.github/dependabot.yml

@@ -36,6 +36,16 @@ updates:
     schedule:
       day: sunday
       interval: weekly
+  -
+    package-ecosystem: gomod
+    directory: /bridge/opencensus
+    labels:
+      - dependencies
+      - go
+      - "Skip Changelog"
+    schedule:
+      day: sunday
+      interval: weekly
   -
     package-ecosystem: gomod
     directory: /example/basic

CHANGELOG.md

@@ -13,6 +13,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - `EventOption` and the related `NewEventConfig` function are added to the `go.opentelemetry.io/otel` package to configure Span events. (#1254)
 - A `TextMapPropagator` and associated `TextMapCarrier` are added to the `go.opentelemetry.io/otel/oteltest` package to test TextMap type propagators and their use. (#1259)
 - `SpanContextFromContext` returns `SpanContext` from context. (#1255)
+- Add an opencensus to opentelemetry tracing bridge. (#1305)
 
 ### Changed
 

bridge/opencensus/bridge.go

@@ -0,0 +1,217 @@
+// Copyright The OpenTelemetry 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 opencensus
+
+import (
+	"context"
+	"fmt"
+
+	octrace "go.opencensus.io/trace"
+
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/global"
+	"go.opentelemetry.io/otel/label"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// NewTracer returns an implementation of the OpenCensus Tracer interface which
+// uses OpenTelemetry APIs.  Using this implementation of Tracer "upgrades"
+// libraries that use OpenCensus to OpenTelemetry to facilitate a migration.
+func NewTracer(tracer trace.Tracer) octrace.Tracer {
+	return &otelTracer{tracer: tracer}
+}
+
+type otelTracer struct {
+	tracer trace.Tracer
+}
+
+var _ octrace.Tracer = (*otelTracer)(nil)
+
+func (o *otelTracer) StartSpan(ctx context.Context, name string, s ...octrace.StartOption) (context.Context, *octrace.Span) {
+	ctx, sp := o.tracer.Start(ctx, name, convertStartOptions(s, name)...)
+	return ctx, octrace.NewSpan(&span{otSpan: sp})
+}
+
+func convertStartOptions(optFns []octrace.StartOption, name string) []trace.SpanOption {
+	var ocOpts octrace.StartOptions
+	for _, fn := range optFns {
+		fn(&ocOpts)
+	}
+	otOpts := []trace.SpanOption{}
+	switch ocOpts.SpanKind {
+	case octrace.SpanKindClient:
+		otOpts = append(otOpts, trace.WithSpanKind(trace.SpanKindClient))
+	case octrace.SpanKindServer:
+		otOpts = append(otOpts, trace.WithSpanKind(trace.SpanKindServer))
+	case octrace.SpanKindUnspecified:
+		otOpts = append(otOpts, trace.WithSpanKind(trace.SpanKindUnspecified))
+	}
+
+	if ocOpts.Sampler != nil {
+		global.Handle(fmt.Errorf("ignoring custom sampler for span %q created by OpenCensus because OpenTelemetry does not support creating a span with a custom sampler", name))
+	}
+	return otOpts
+}
+
+func (o *otelTracer) StartSpanWithRemoteParent(ctx context.Context, name string, parent octrace.SpanContext, s ...octrace.StartOption) (context.Context, *octrace.Span) {
+	// make sure span context is zero'd out so we use the remote parent
+	ctx = trace.ContextWithSpan(ctx, nil)
+	ctx = trace.ContextWithRemoteSpanContext(ctx, ocSpanContextToOTel(parent))
+	return o.StartSpan(ctx, name, s...)
+}
+
+func (o *otelTracer) FromContext(ctx context.Context) *octrace.Span {
+	otSpan := trace.SpanFromContext(ctx)
+	return octrace.NewSpan(&span{otSpan: otSpan})
+}
+
+func (o *otelTracer) NewContext(parent context.Context, s *octrace.Span) context.Context {
+	if otSpan, ok := s.Internal().(*span); ok {
+		return trace.ContextWithSpan(parent, otSpan.otSpan)
+	}
+	global.Handle(fmt.Errorf("unable to create context with span %q, since it was created using a different tracer", s.String()))
+	return parent
+}
+
+type span struct {
+	otSpan trace.Span
+}
+
+func (s *span) IsRecordingEvents() bool {
+	return s.otSpan.IsRecording()
+}
+
+func (s *span) End() {
+	s.otSpan.End()
+}
+
+func (s *span) SpanContext() octrace.SpanContext {
+	return otelSpanContextToOc(s.otSpan.SpanContext())
+}
+
+func (s *span) SetName(name string) {
+	s.otSpan.SetName(name)
+}
+
+func (s *span) SetStatus(status octrace.Status) {
+	s.otSpan.SetStatus(codes.Code(status.Code), status.Message)
+}
+
+func (s *span) AddAttributes(attributes ...octrace.Attribute) {
+	s.otSpan.SetAttributes(convertAttributes(attributes)...)
+}
+
+func convertAttributes(attributes []octrace.Attribute) []label.KeyValue {
+	otAttributes := make([]label.KeyValue, len(attributes))
+	for i, a := range attributes {
+		otAttributes[i] = label.KeyValue{
+			Key:   label.Key(a.Key()),
+			Value: convertValue(a.Value()),
+		}
+	}
+	return otAttributes
+}
+
+func convertValue(ocval interface{}) label.Value {
+	switch v := ocval.(type) {
+	case bool:
+		return label.BoolValue(v)
+	case int64:
+		return label.Int64Value(v)
+	case float64:
+		return label.Float64Value(v)
+	case string:
+		return label.StringValue(v)
+	default:
+		return label.StringValue("unknown")
+	}
+}
+
+func (s *span) Annotate(attributes []octrace.Attribute, str string) {
+	s.otSpan.AddEvent(str, trace.WithAttributes(convertAttributes(attributes)...))
+}
+
+func (s *span) Annotatef(attributes []octrace.Attribute, format string, a ...interface{}) {
+	s.Annotate(attributes, fmt.Sprintf(format, a...))
+}
+
+var (
+	uncompressedKey = label.Key("uncompressed byte size")
+	compressedKey   = label.Key("compressed byte size")
+)
+
+func (s *span) AddMessageSendEvent(messageID, uncompressedByteSize, compressedByteSize int64) {
+	s.otSpan.AddEvent("message send",
+		trace.WithAttributes(
+			label.KeyValue{
+				Key:   uncompressedKey,
+				Value: label.Int64Value(uncompressedByteSize),
+			},
+			label.KeyValue{
+				Key:   compressedKey,
+				Value: label.Int64Value(compressedByteSize),
+			}),
+	)
+}
+
+func (s *span) AddMessageReceiveEvent(messageID, uncompressedByteSize, compressedByteSize int64) {
+	s.otSpan.AddEvent("message receive",
+		trace.WithAttributes(
+			label.KeyValue{
+				Key:   uncompressedKey,
+				Value: label.Int64Value(uncompressedByteSize),
+			},
+			label.KeyValue{
+				Key:   compressedKey,
+				Value: label.Int64Value(compressedByteSize),
+			}),
+	)
+}
+
+func (s *span) AddLink(l octrace.Link) {
+	global.Handle(fmt.Errorf("ignoring OpenCensus link %+v for span %q because OpenTelemetry doesn't support setting links after creation", l, s.String()))
+}
+
+func (s *span) String() string {
+	return fmt.Sprintf("span %s", s.otSpan.SpanContext().SpanID.String())
+}
+
+func otelSpanContextToOc(sc trace.SpanContext) octrace.SpanContext {
+	if sc.IsDebug() || sc.IsDeferred() {
+		global.Handle(fmt.Errorf("ignoring OpenTelemetry Debug or Deferred trace flags for span %q because they are not supported by OpenCensus", sc.SpanID))
+	}
+	var to octrace.TraceOptions
+	if sc.IsSampled() {
+		// OpenCensus doesn't expose functions to directly set sampled
+		to = 0x1
+	}
+	return octrace.SpanContext{
+		TraceID:      octrace.TraceID(sc.TraceID),
+		SpanID:       octrace.SpanID(sc.SpanID),
+		TraceOptions: to,
+	}
+}
+
+func ocSpanContextToOTel(sc octrace.SpanContext) trace.SpanContext {
+	var traceFlags byte
+	if sc.IsSampled() {
+		traceFlags = trace.FlagsSampled
+	}
+	return trace.SpanContext{
+		TraceID:    trace.TraceID(sc.TraceID),
+		SpanID:     trace.SpanID(sc.SpanID),
+		TraceFlags: traceFlags,
+	}
+}