[WIP] Set default propagator to no-op propagator

- add set propagator to examples

Signed-off-by: Hui Kang <kangh@us.ibm.com>
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>

CHANGELOG.md

@@ -70,6 +70,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Renamed `SamplingDecision` values to comply with OpenTelemetry specification change. (#1192)
 - Renamed Zipkin attribute names from `ot.status_code & ot.status_description` to `otel.status_code & otel.status_description`. (#1201)
 - The default SDK now invokes registered `SpanProcessor`s in the order they were registered with the `TracerProvider`. (#1195)
+- The default propagator is no-op propagator. (#1184)
 
 ### Removed
 

api/global/internal/state.go

@@ -18,11 +18,9 @@ import (
 	"sync"
 	"sync/atomic"
 
-	"go.opentelemetry.io/otel/api/baggage"
 	"go.opentelemetry.io/otel/api/metric"
 	"go.opentelemetry.io/otel/api/propagation"
 	"go.opentelemetry.io/otel/api/trace"
-	"go.opentelemetry.io/otel/propagators"
 )
 
 type (
@@ -120,14 +118,12 @@ func defaultPropagatorsValue() *atomic.Value {
 	return v
 }
 
-// getDefaultPropagators returns a default Propagators, configured
-// with W3C trace and baggage propagation.
+// getDefaultPropagators returns a default noop Propagators
 func getDefaultPropagators() propagation.Propagators {
-	tcPropagator := propagators.TraceContext{}
-	bagPropagator := baggage.Baggage{}
+	noopPropagator := propagation.NoopPropagator{}
 	return propagation.New(
-		propagation.WithExtractors(tcPropagator, bagPropagator),
-		propagation.WithInjectors(tcPropagator, bagPropagator),
+		propagation.WithExtractors(noopPropagator),
+		propagation.WithInjectors(noopPropagator),
 	)
 }
 

api/propagation/noop_propagator.go

@@ -0,0 +1,34 @@
+// 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 propagation
+
+import (
+	"context"
+)
+
+type NoopPropagator struct {
+}
+
+var _ HTTPPropagator = NoopPropagator{}
+
+func (p NoopPropagator) Extract(ctx context.Context, supplier HTTPSupplier) context.Context {
+	return ctx
+}
+
+func (NoopPropagator) Inject(context.Context, HTTPSupplier) {}
+
+func (NoopPropagator) GetAllKeys() []string {
+	return nil
+}

example/basic/main.go

@@ -21,6 +21,7 @@ import (
 	"go.opentelemetry.io/otel/api/baggage"
 	"go.opentelemetry.io/otel/api/global"
 	"go.opentelemetry.io/otel/api/metric"
+	"go.opentelemetry.io/otel/api/propagation"
 	"go.opentelemetry.io/otel/api/trace"
 	"go.opentelemetry.io/otel/exporters/stdout"
 	"go.opentelemetry.io/otel/label"
@@ -61,6 +62,11 @@ func main() {
 	global.SetTracerProvider(tp)
 	global.SetMeterProvider(pusher.MeterProvider())
 
+	bagPropagator := baggage.DefaultHTTPPropagator()
+	props := propagation.New(propagation.WithExtractors(bagPropagator),
+		propagation.WithInjectors(bagPropagator))
+
+	global.SetPropagators(props)
 	tracer := global.Tracer("ex.com/basic")
 	meter := global.Meter("ex.com/basic")
 

example/otel-collector/main.go

@@ -27,9 +27,11 @@ import (
 
 	"go.opentelemetry.io/otel/api/global"
 	"go.opentelemetry.io/otel/api/metric"
+	"go.opentelemetry.io/otel/api/propagation"
 	apitrace "go.opentelemetry.io/otel/api/trace"
 	"go.opentelemetry.io/otel/exporters/otlp"
 	"go.opentelemetry.io/otel/label"
+	"go.opentelemetry.io/otel/propagators"
 	"go.opentelemetry.io/otel/sdk/metric/controller/push"
 	"go.opentelemetry.io/otel/sdk/metric/processor/basic"
 	"go.opentelemetry.io/otel/sdk/metric/selector/simple"
@@ -73,6 +75,10 @@ func initProvider() func() {
 		push.WithPeriod(2*time.Second),
 	)
 
+	tcPropagator := propagators.TraceContext{}
+	props := propagation.New(propagation.WithExtractors(tcPropagator),
+		propagation.WithInjectors(tcPropagator))
+	global.SetPropagators(props)
 	global.SetTracerProvider(tracerProvider)
 	global.SetMeterProvider(pusher.MeterProvider())
 	pusher.Start()