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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package otelhttp_test
import (
"context"
"fmt"
"io"
"log"
"net/http"
"strings"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/trace"
"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
)
func ExampleNewHandler() {
/* curl -v -d "a painting" http://localhost:7777/hello/bob/ross
...
* upload completely sent off: 10 out of 10 bytes
< HTTP/1.1 200 OK
< Traceparent: 00-76ae040ee5753f38edf1c2bd9bd128bd-dd394138cfd7a3dc-01
< Date: Fri, 04 Oct 2019 02:33:08 GMT
< Content-Length: 45
< Content-Type: text/plain; charset=utf-8
<
Hello, bob/ross!
You sent me this:
a painting
*/
figureOutName := func(ctx context.Context, s string) (string, error) {
pp := strings.SplitN(s, "/", 2)
var err error
switch pp[1] {
case "":
err = fmt.Errorf("expected /hello/:name in %q", s)
default:
trace.SpanFromContext(ctx).SetAttributes(attribute.String("name", pp[1]))
}
return pp[1], err
}
var mux http.ServeMux
mux.Handle("/hello/",
otelhttp.WithRouteTag("/hello/:name", http.HandlerFunc(
func(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
labeler, _ := otelhttp.LabelerFromContext(ctx)
var name string
// Wrap another function in its own span
if err := func(ctx context.Context) error {
ctx, span := trace.SpanFromContext(ctx).TracerProvider().Tracer("exampleTracer").Start(ctx, "figureOutName")
defer span.End()
var err error
name, err = figureOutName(ctx, r.URL.Path[1:])
return err
}(ctx); err != nil {
log.Println("error figuring out name: ", err)
http.Error(w, err.Error(), http.StatusInternalServerError)
labeler.Add(attribute.Bool("error", true))
return
}
d, err := io.ReadAll(r.Body)
if err != nil {
log.Println("error reading body: ", err)
w.WriteHeader(http.StatusBadRequest)
labeler.Add(attribute.Bool("error", true))
return
}
n, err := io.WriteString(w, "Hello, "+name+"!\nYou sent me this:\n"+string(d))
if err != nil {
log.Printf("error writing reply after %d bytes: %s", n, err)
labeler.Add(attribute.Bool("error", true))
}
}),
),
)
if err := http.ListenAndServe(":7777", //nolint:gosec // Ignoring G114: Use of net/http serve function that has no support for setting timeouts.
otelhttp.NewHandler(&mux, "server",
otelhttp.WithMessageEvents(otelhttp.ReadEvents, otelhttp.WriteEvents),
),
); err != nil {
log.Fatal(err)
}
}
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