---
tags: golang, gin, graceful shutdown
---
# golang graceful shutdown machinism

## reference
[go graceful shutdown video](https://www.youtube.com/watch?v=nCn1Wmi6Wug)

## Question decription

when server suddenly hit situation, server connect shutdown directly not graceful for connected proccess

go httd module provide a Shutdown method to Gracefully handle connected process before shutdown
## Prerequis

go version must great than 1.8

## sample to handel this
gin server with restful api

func main() {
    router := gin.Default()
	router.GET("/", func(c *gin.Context) {
		time.Sleep(5 * time.Second)
		c.String(http.StatusOK, "Welcome Gin Server\n")
	})

	srv := &http.Server{
		Addr:    ":8080",
		Handler: router,
	}
	
    if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
        log.Fatalf("listen: %s\n", err)
    }
}

## solution

1 move listen handler into goroutine(make server handler process into daemon)
2 setup a channel to listen SIGINT and SIGTERM for shutdown signal
3 setup withTimeout for preserve how many time to close the connection

func main() {
    router := gin.Default()
	router.GET("/", func(c *gin.Context) {
		time.Sleep(5 * time.Second)
		c.String(http.StatusOK, "Welcome Gin Server\n")
	})

	srv := &http.Server{
		Addr:    ":8080",
		Handler: router,
	}
    //1 set up handler to go routine
	go func() {
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatalf("listen: %s\n", err)
		}
	}()
    // 2 make channel for listen os.Siganal and setup notify Signal
	quit := make(chan os.Signal, 1)

	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
	<-quit
	log.Println("Shutdown Server ...")

    // 3 setup withTimeout to preserve connection before close
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	if err := srv.Shutdown(ctx); err != nil {
		log.Fatal("Server Shutdown: ", err)
	}
	log.Println("Server exiting")
}

## repo
[go-httpd-graceful-shutdown](https://github.com/yuanyu90221/go-httd-graceful-shutdown)