server.go

package main

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

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Connection", "close")
		fmt.Fprintln(w, "OK")
	})
	server := &http.Server{
		Addr:         ":8080",
		Handler:      mux,
		ReadTimeout:  5 * time.Second,
		WriteTimeout: 5 * time.Second,
	}

	done := make(chan struct{})
	go func() {
		sig := make(chan os.Signal)
		signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
		<-sig
		if err := server.Shutdown(context.Background()); err != nil {
			log.Printf("HTTP server Shutdown: %v", err)
		}
		close(done)
	}()

	if err := server.ListenAndServe(); err != http.ErrServerClosed {
		log.Printf("HTTP server ListenAndServe: %v", err)
	}
	<-done
}