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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package main
import (
"context"
"errors"
"log"
"net"
"net/http"
"os"
"os/signal"
"time"
"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
)
func main() {
if err := run(); err != nil {
log.Fatalln(err)
}
}
func run() (err error) {
// Handle SIGINT (CTRL+C) gracefully.
ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
defer stop()
// Set up OpenTelemetry.
otelShutdown, err := setupOTelSDK(ctx)
if err != nil {
return
}
// Handle shutdown properly so nothing leaks.
defer func() {
err = errors.Join(err, otelShutdown(context.Background()))
}()
// Start HTTP server.
srv := &http.Server{
Addr: ":8080",
BaseContext: func(_ net.Listener) context.Context { return ctx },
ReadTimeout: time.Second,
WriteTimeout: 10 * time.Second,
Handler: newHTTPHandler(),
}
srvErr := make(chan error, 1)
go func() {
srvErr <- srv.ListenAndServe()
}()
// Wait for interruption.
select {
case err = <-srvErr:
// Error when starting HTTP server.
return
case <-ctx.Done():
// Wait for first CTRL+C.
// Stop receiving signal notifications as soon as possible.
stop()
}
// When Shutdown is called, ListenAndServe immediately returns ErrServerClosed.
err = srv.Shutdown(context.Background())
return
}
func newHTTPHandler() http.Handler {
mux := http.NewServeMux()
// handleFunc is a replacement for mux.HandleFunc
// which enriches the handler's HTTP instrumentation with the pattern as the http.route.
handleFunc := func(pattern string, handlerFunc func(http.ResponseWriter, *http.Request)) {
// Configure the "http.route" for the HTTP instrumentation.
handler := otelhttp.WithRouteTag(pattern, http.HandlerFunc(handlerFunc))
mux.Handle(pattern, handler)
}
// Register handlers.
handleFunc("/rolldice/", rolldice)
handleFunc("/rolldice/{player}", rolldice)
// Add HTTP instrumentation for the whole server.
handler := otelhttp.NewHandler(mux, "/")
return handler
}
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