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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package main
import (
"context"
"flag"
"fmt"
"io"
"log"
"net/http"
"time"
"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/baggage"
stdout "go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
"go.opentelemetry.io/otel/propagation"
sdktrace "go.opentelemetry.io/otel/sdk/trace"
semconv "go.opentelemetry.io/otel/semconv/v1.20.0"
"go.opentelemetry.io/otel/trace"
)
func initTracer() (*sdktrace.TracerProvider, error) {
// Create stdout exporter to be able to retrieve
// the collected spans.
exporter, err := stdout.New(stdout.WithPrettyPrint())
if err != nil {
return nil, err
}
// For the demonstration, use sdktrace.AlwaysSample sampler to sample all traces.
// In a production application, use sdktrace.ProbabilitySampler with a desired probability.
tp := sdktrace.NewTracerProvider(
sdktrace.WithSampler(sdktrace.AlwaysSample()),
sdktrace.WithBatcher(exporter),
)
otel.SetTracerProvider(tp)
otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
return tp, err
}
func main() {
tp, err := initTracer()
if err != nil {
log.Fatal(err)
}
defer func() {
if err := tp.Shutdown(context.Background()); err != nil {
log.Printf("Error shutting down tracer provider: %v", err)
}
}()
url := flag.String("server", "http://localhost:7777/hello", "server url")
flag.Parse()
client := http.Client{Transport: otelhttp.NewTransport(http.DefaultTransport)}
bag, _ := baggage.Parse("username=donuts")
ctx := baggage.ContextWithBaggage(context.Background(), bag)
var body []byte
tr := otel.Tracer("example/client")
err = func(ctx context.Context) error {
ctx, span := tr.Start(ctx, "say hello", trace.WithAttributes(semconv.PeerService("ExampleService")))
defer span.End()
req, _ := http.NewRequestWithContext(ctx, "GET", *url, nil)
fmt.Printf("Sending request...\n")
res, err := client.Do(req)
if err != nil {
panic(err)
}
body, err = io.ReadAll(res.Body)
_ = res.Body.Close()
return err
}(ctx)
if err != nil {
log.Fatal(err)
}
fmt.Printf("Response Received: %s\n\n\n", body)
fmt.Printf("Waiting for few seconds to export spans ...\n\n")
time.Sleep(10 * time.Second)
fmt.Printf("Inspect traces on stdout\n")
}
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