Graceful shutdown

main.go

package main

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

func index(w http.ResponseWriter, r *http.Request) {
	time.Sleep(10 * time.Second)
	json.NewEncoder(w).Encode(map[string]any{
		"code":    http.StatusOK,
		"message": "server up",
	})
}

func main() {
	srv := &http.Server{
		Addr:    "localhost:3000",
		Handler: nil,
	}

	http.HandleFunc("/", index)

	// run server menggunakan goroutine
	go func() {
		log.Println("server running at", srv.Addr)
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatal("error listening", err)
		}
	}()

	// buat channel dan terima sinyal interrupt atau sigterm
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt)
	signal.Notify(c, syscall.SIGTERM)

	// masukkin data channel ke variabel sig
	// dan close channelnya
	sig := <-c
	log.Println("got signal", sig)
	defer close(c)

	// buat context dengan timeout
	// 30 detik
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	// proses shutting down server
	log.Println("shutting down server..")
	if err := srv.Shutdown(ctx); err != nil {
		log.Fatal("error shutting down server", err)
	}

	log.Println("server shutted down successfully")
}