Graceful Shutdown for Go HTTP servers

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func main() {
	srv := &http.Server{
		Addr:    ":8080",
		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			time.Sleep(5 * time.Second)
			_, _ = w.Write([]byte("hello"))
		}),
	}

	if err := gracefulShutdown(srv, 10*time.Second); err != nil {
		log.Println(err)
	}
}

// gracefulShutdown stops the given HTTP server on
// receiving a stop signal and waits for the active connections
// to be closed for {timeout} period of time.
func gracefulShutdown(srv *http.Server, timeout time.Duration) error {
	done := make(chan error, 1)
	go func() {
		c := make(chan os.Signal, 1)
		signal.Notify(c, os.Interrupt, syscall.SIGTERM)
		<-c

		ctx := context.Background()
		var cancel context.CancelFunc
		if timeout > 0 {
			ctx, cancel = context.WithTimeout(ctx, timeout)
			defer cancel()
		}

		done <- srv.Shutdown(ctx)
	}()

	if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
		return err
	}

	return <-done
}