Go: Graceful HTTP Server Shutdown

graceful_http_server_shutdown.go

package main

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

func main() {
	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer cancel()
	if err := run(ctx); err != nil {
		log.Fatal(err)
	}
}

func run(ctx context.Context) error {
	host := ""
	port := "8080"
	root := http.NewServeMux()
	s := &http.Server{
		Addr:    net.JoinHostPort(host, port),
		Handler: root,
		// BaseContext: func(_ net.Listener) context.Context { return ctx },
	}
	defer func() {
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		slog.Info("Shutting down...")
		if err := s.Shutdown(ctx); err != nil {
			slog.Error("Shutdown failed", "err", err)
		}
	}()
	listenAndServe := func() <-chan error {
		err := make(chan error, 1)
		go func() { err <- s.ListenAndServe() }()
		return err
	}
	select {
	case err := <-listenAndServe():
		return err
	case <-ctx.Done():
		return ctx.Err()
	}
}