go http server 优雅停机

package main

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

func main() {
	var srv http.Server

	idleConnsClosed := make(chan struct{})
	go func() {
		sigint := make(chan os.Signal, 1)
		signal.Notify(sigint, os.Interrupt)
		<-sigint

		// We received an interrupt signal, shut down.
		ctx, cancel := context.WithTimeout(context.Background(), 30 * time.Second)
		if err := srv.Shutdown(ctx); err != nil {
			// Error from closing listeners, or context timeout:
			log.Printf("HTTP server Shutdown: %v", err)
		}
		cancel()
		close(idleConnsClosed)
	}()

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

	<-idleConnsClosed
}

优雅停机(无损下线)体现在哪里?

1. 设置超时时长

接收到Ctrl + C后，设置一个超时时长，如果等待优雅停机时长超时，则立即退出

2. 使用了srv.Shutdown(ctx)

Shutdown gracefully shuts down the server without interrupting any active connections. Shutdown works by first closing all open listeners, then closing all idle connections, and then waiting indefinitely for connections to return to idle and then shut down. If the provided context expires before the shutdown is complete, Shutdown returns the context's error, otherwise it returns any error returned from closing the Server's underlying Listener(s).

• 关闭所有接收TCP连接的Listener
• 关闭所有空闲TCP连接
• 等待所有活跃连接变成空闲