Set default propagator to no-op propagator (#1204)

- add set propagator to examples

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

Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>

CHANGELOG.md

@@ -12,6 +12,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - OTLP Metric exporter supports Histogram aggregation. (#1209)
 
+### Changed
+
+- Set default propagator to no-op propagator. (#1184)
+
 ## [0.12.0] - 2020-09-24
 
 ### Added

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 (
@@ -120,15 +118,9 @@ 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{}
-	return propagation.New(
-		propagation.WithExtractors(tcPropagator, bagPropagator),
-		propagation.WithInjectors(tcPropagator, bagPropagator),
-	)
+	return propagation.New()
 }
 
 // ResetForTest restores the initial global state, for testing purposes.

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 +62,12 @@ func main() {
 	global.SetTracerProvider(tp)
 	global.SetMeterProvider(pusher.MeterProvider())
 
+	// set propagator to baggage since the default is no-op
+	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()