Graceful Shutdown

Graceful Shutdown

func main() {
	//
	// Startup
	//

	// ...

	server := &http.Server{
		Addr:         ":8080",
		Handler:      engin,
	}

	listenErr := make(chan error, 1)

	go func() {
		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			listenErr <- err
		}
	}()

	// ...

	shutdown := make(chan os.Signal, 1)
	signal.Notify(shutdown, syscall.SIGINT, syscall.SIGTERM)

	select {
	case err := <-listenErr:
		logger.Logger(context.Background()).Error("failed to listen and serve", zap.Error(err))
	case <-shutdown:
	}

	//
	// Shutdown
	//
	logger.Logger(context.Background()).Info("shutting down...")

	wg := &sync.WaitGroup{}

	go func() {
		defer wg.Done()

		ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
		defer cancel()

		// blocked until all connections are closed or timeout
		if err := server.Shutdown(ctx); err != nil {
			logger.Logger(context.Background()).Error("failed to shutdown server", zap.Error(err))
		}
	}()
	wg.Add(1)

	// ...

	wg.Wait()
}