Merge pull request #913 from devlights/update-http-server-shutdown-example

Author: devlights

examples/http/shutdown/.gitignore

@@ -0,0 +1 @@
+server

examples/http/shutdown/Taskfile.yml

@@ -1,6 +1,11 @@
 version: '3'
 
 tasks:
-  run:
+  default:
     cmds:
-      - go run -race main.go
+      - go build -o server main.go
+      - ./server &
+      - sleep 1
+      - curl http://localhost:8888/
+      - curl http://localhost:8888/something
+      - kill -INT $(pgrep server)

examples/http/shutdown/main.go

@@ -2,43 +2,97 @@ package main
 
 import (
 	"context"
+	"errors"
+	"fmt"
 	"log"
 	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
 	"time"
 )
 
 func main() {
+	log.SetFlags(log.Lmicroseconds)
+
+	if err := run(); err != nil {
+		log.Fatalf("Application failed: %v", err)
+	}
+}
+
+func run() error {
 	var (
-		mux              = http.NewServeMux()
-		srv              = &http.Server{Addr: ":8888", Handler: mux}
-		mainCtx          = context.Background()
-		procCtx, procCxl = context.WithTimeout(mainCtx, 3*time.Second)
+		port string
 	)
-	defer procCxl()
+	if port = os.Getenv("PORT"); port == "" {
+		port = "8888"
+	}
 
-	// ----------- Start ----------- //
+	var (
+		mux = http.NewServeMux()
+		srv = &http.Server{
+			Addr:           ":" + port,
+			Handler:        mux,
+			MaxHeaderBytes: 1 << 20, // 1MB
+			ReadTimeout:    10 * time.Second,
+			WriteTimeout:   10 * time.Second,
+			IdleTimeout:    120 * time.Second,
+		}
+		mainCtx, mainCxl = context.WithCancel(context.Background())
+		errs             = make(chan error, 1)
+	)
+	defer mainCxl()
 
+	// ----------- Handlers ----------- //
+	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintln(w, "Hello World")
+	})
+
+	// ----------- Start ----------- //
 	go func() {
-		log.Println("Server is up.")
-		srv.ListenAndServe()
+		log.Printf("Server is listening on %s", srv.Addr)
+		if err := srv.ListenAndServe(); err != nil {
+			errs <- err
+		}
 	}()
 
-	<-procCtx.Done()
-
-	// ----------- Shutdown ----------- //
-
+	// ----------- Signals ----------- //
 	var (
-		shutdownCtx, shutdownCxl = context.WithTimeout(mainCtx, 1*time.Second)
+		sigs = make(chan os.Signal, 1)
 	)
-	defer shutdownCxl()
-
-	if err := srv.Shutdown(shutdownCtx); err != nil {
-		switch err {
-		case context.DeadlineExceeded:
-			log.Println("Server shutdown process timed out.")
-		default:
-			log.Fatal(err)
+	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
+	defer signal.Stop(sigs)
+
+	// ----------- Selects ----------- //
+	select {
+	case err := <-errs:
+		if !errors.Is(err, http.ErrServerClosed) {
+			return fmt.Errorf("server error: %w", err)
 		}
+		return nil
+	case sig := <-sigs:
+		log.Printf("Shutdown started: %v", sig)
+
+		// ----------- Shutdown ----------- //
+		shutCtx, shutCxl := context.WithTimeout(mainCtx, 5*time.Second)
+		defer shutCxl()
+
+		if err := srv.Shutdown(shutCtx); err != nil {
+			if errors.Is(err, context.DeadlineExceeded) {
+				log.Println("Server shutdown process timed out.")
+			} else {
+				log.Printf("Server shutdown failed: %v", err)
+			}
+
+			if closeErr := srv.Close(); closeErr != nil {
+				return fmt.Errorf("force close failed: %w", closeErr)
+			}
+
+			return fmt.Errorf("shutdown error: %w", err)
+		}
+
+		log.Println("Server has been gracefully shutdown.")
+
+		return nil
 	}
-	log.Println("Server has been shutdown.")
 }