Graceful shutdown of a Go HTTP server

main.go

package main

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

func main() {
	srv := &http.Server{Addr: ":8080"}

	idleConnsClosed := make(chan struct{})
	go func() {
		stopChan := make(chan os.Signal, 1)

		// subscribe to SIGINT and SIGTERM signals
		signal.Notify(stopChan, syscall.SIGINT, syscall.SIGTERM)

		// wait for SIGINT
		<-stopChan

		log.Println("Shutting down server...")

		// shut down gracefully, but wait no longer than 5 seconds before halting
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()

		// We received an interrupt signal, shut down.
		if err := srv.Shutdown(ctx); err != nil {
			// Error from closing listeners, or context timeout:
			log.Printf("HTTP server Shutdown: %v", err)
		}

		// Unblock the main function
		close(idleConnsClosed)
	}()

	log.Println("Listening on", srv.Addr)

	// service connections
	if err := srv.ListenAndServe(); err != http.ErrServerClosed {
		// Error starting or closing listener:
		log.Panicf("HTTP server ListenAndServe: %v", err)
	}

	<-idleConnsClosed

	log.Println("Server gracefully stopped")
}