Go http.ServerのGraceful shutdown

Go 1.8 からはhttp.ServerにGraceful Shutdownを行うための仕組みが備わっている context.Contextを渡すことで猶予時間を決めてリクエスト中の処理の終了を待つことができる

net/http の場合

package main
 
import (
	"context"
	"errors"
	"log"
	"net/http"
	"os/signal"
	"syscall"
	"time"
)
 
func main() {
	http.HandleFunc("GET /ping", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("OK"))
	})
 
	srv := http.Server{
		Addr: ":3000",
	}
 
	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()
 
	go func() {
		if err := srv.ListenAndServe(); !errors.Is(err, http.ErrServerClosed) {
			log.Fatalf("Failed to listen and serve: %v\n", err)
		}
	}()
 
	// wait until receive signal
	<-ctx.Done()
	stop()
	log.Println("Shutting down gracefully, press Ctrl+C again to force")
 
	// wait processing request up to 10 seconds
	shutdownCtx, shutdownRelease := context.WithTimeout(context.Background(), 10*time.Second)
	defer shutdownRelease()
 
	if err := srv.Shutdown(shutdownCtx); err != nil {
		log.Printf("Server forced to shutdown: %v\n", err)
	}
 
	log.Println("Server exiting")
}

signal.NotifyContext ではなく signal.Notify を使う例も見かけるがラップしているだけなのでだいたい同じ

	quit := make(chan os.Signal, 1)
	signal.Notify(quit, os.Interrupt, syscall.SIGTERM)
 
	<-quit
 

Echoの場合

公式に紹介されている。 Graceful Shutdown | Echo

package main
 
import (
	"context"
	"net/http"
	"os"
	"os/signal"
	"time"
 
	"github.com/labstack/echo/v4"
	"github.com/labstack/gommon/log"
)
 
func main() {
	// Setup
	e := echo.New()
	e.Logger.SetLevel(log.INFO)
	e.GET("/", func(c echo.Context) error {
		time.Sleep(5 * time.Second)
		return c.JSON(http.StatusOK, "OK")
	})
 
	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
	defer stop()
	// Start server
	go func() {
		if err := e.Start(":1323"); err != nil && err != http.ErrServerClosed {
			e.Logger.Fatal("shutting down the server")
		}
	}()
 
	// Wait for interrupt signal to gracefully shutdown the server with a timeout of 10 seconds.
	<-ctx.Done()
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	if err := e.Shutdown(ctx); err != nil {
		e.Logger.Fatal(err)
	}
}