*http.Server in Go 1.8 supports graceful shutdown. This is a small example.

graceful.go

package main

import (
	"context"
	"log"
	"net/http"
	"os"
	"os/signal"
	"time"
)

type Server struct {
	logger *log.Logger
	mux    *http.ServeMux
}

func NewServer(options ...func(*Server)) *Server {
	s := &Server{
		logger: log.New(os.Stdout, "", 0),
		mux:    http.NewServeMux(),
	}

	for _, f := range options {
		f(s)
	}

	s.mux.HandleFunc("/", s.index)

	return s
}

func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	s.mux.ServeHTTP(w, r)
}

func (s *Server) index(w http.ResponseWriter, r *http.Request) {
	s.logger.Println("GET /")

	w.Write([]byte("Hello, World!"))
}

func main() {
	stop := make(chan os.Signal, 1)

	signal.Notify(stop, os.Interrupt)

	logger := log.New(os.Stdout, "", 0)

	addr := ":" + os.Getenv("PORT")
	if addr == ":" {
		addr = ":2017"
	}

	s := NewServer(func(s *Server) { s.logger = logger })

	h := &http.Server{Addr: addr, Handler: s}

	go func() {
		logger.Printf("Listening on http://0.0.0.0%s\n", addr)

		if err := h.ListenAndServe(); err != nil {
			logger.Fatal(err)
		}
	}()

	<-stop

	logger.Println("\nShutting down the server...")

	ctx, _ := context.WithTimeout(context.Background(), 5*time.Second)

	h.Shutdown(ctx)

	logger.Println("Server gracefully stopped")
}

@peterhellberg Thanks for sharing this!

Hi, great contribution.

There is one thing that could make it more complete in my opinion.

Everywhere this code is, it will always print "Listening on http://...." in the console, even if ListenAndServe() was unable to start actually listening.

	log.Printf("Listening on http://0.0.0.0%s\n", hs.Addr)

	if err := hs.ListenAndServe(); err != http.ErrServerClosed {
		log.Fatal(err)
	}

If you start 1 server, you'll see this in the console:

Listening on http://0.0.0.0:2017

If you start a 2nd server without shutting down the 1st one, you will see this in the console:

Listening on http://0.0.0.0:2017
panic... listen tcp :2017: bind: address already in use

So it first shows "Listening on http://..." however this never actually happened.

I'm not a go expert, is there a way to implement this?

-- UPDATE

Apparently using http.Listen and http.Serve individually, it is possible to catch a port in use error (or any other error while trying to listen to a tcp network) before assuming the server is listening.

Source: https://stackoverflow.com/a/48250354/194630

	listener, err := net.Listen("tcp", ":"+config.Port)
	if err != nil {
		log.Fatal(err)
	}

	done := make(chan bool)
	go server.Serve(listener)

	// Log server started
	log.Printf("Server started at port %v", config.Port)
	<-done