mirror of
https://github.com/open-telemetry/opentelemetry-go.git
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f5b4e99025
Part of #5412 - Use the recommended package name for the instrumentation exemplified in the repository. - Use the recommended detection of a `TracerProvider` from passed context.
90 lines
2.9 KiB
Go
90 lines
2.9 KiB
Go
// Copyright The OpenTelemetry Authors
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// SPDX-License-Identifier: Apache-2.0
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package main
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import (
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"context"
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"fmt"
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"log"
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"net/http"
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"time"
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"go.opentelemetry.io/otel"
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"go.opentelemetry.io/otel/example/passthrough/handler"
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"go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
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"go.opentelemetry.io/otel/propagation"
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sdktrace "go.opentelemetry.io/otel/sdk/trace"
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"go.opentelemetry.io/otel/trace"
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)
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const name = "go.opentelemetry.io/otel/example/passthrough"
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func main() {
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ctx := context.Background()
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initPassthroughGlobals()
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tp, err := nonGlobalTracer()
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if err != nil {
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log.Fatal(err)
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}
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defer func() { _ = tp.Shutdown(ctx) }()
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// make an initial http request
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r, err := http.NewRequest("", "", nil)
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if err != nil {
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panic(err)
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}
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// This is roughly what an instrumented http client does.
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log.Println("The \"make outer request\" span should be recorded, because it is recorded with a Tracer from the SDK TracerProvider")
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var span trace.Span
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tracer := tp.Tracer(name)
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ctx, span = tracer.Start(ctx, "make outer request")
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defer span.End()
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r = r.WithContext(ctx)
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otel.GetTextMapPropagator().Inject(ctx, propagation.HeaderCarrier(r.Header))
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backendFunc := func(r *http.Request) {
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// This is roughly what an instrumented http server does.
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ctx := r.Context()
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tp := trace.SpanFromContext(ctx).TracerProvider()
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tracer := tp.Tracer(name)
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ctx = otel.GetTextMapPropagator().Extract(ctx, propagation.HeaderCarrier(r.Header))
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log.Println("The \"handle inner request\" span should be recorded, because it is recorded with a Tracer from the SDK TracerProvider")
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_, span := tracer.Start(ctx, "handle inner request")
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defer span.End()
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// Do "backend work"
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time.Sleep(time.Second)
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}
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// This handler will be a passthrough, since we didn't set a global TracerProvider
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passthroughHandler := handler.New(backendFunc)
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passthroughHandler.HandleHTTPReq(r)
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}
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func initPassthroughGlobals() {
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// We explicitly DO NOT set the global TracerProvider using otel.SetTracerProvider().
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// The unset TracerProvider returns a "non-recording" span, but still passes through context.
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log.Println("Register a global TextMapPropagator, but do not register a global TracerProvider to be in \"passthrough\" mode.")
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log.Println("The \"passthrough\" mode propagates the TraceContext and Baggage, but does not record spans.")
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otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
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}
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// nonGlobalTracer creates a trace provider instance for testing, but doesn't
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// set it as the global tracer provider.
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func nonGlobalTracer() (*sdktrace.TracerProvider, error) {
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exp, err := stdouttrace.New(stdouttrace.WithPrettyPrint())
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if err != nil {
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return nil, fmt.Errorf("failed to initialize stdouttrace exporter: %w", err)
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}
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bsp := sdktrace.NewBatchSpanProcessor(exp)
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tp := sdktrace.NewTracerProvider(
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sdktrace.WithSampler(sdktrace.AlwaysSample()),
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sdktrace.WithSpanProcessor(bsp),
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)
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return tp, nil
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}
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