Golang HTTP 服务平滑重启及升级的思路

func (h *Server) ListenAndServe(listenAddress string) error {
 // ....
 return gracehttp.Serve(&http.Server{
 Addr: listenAddress,
 Handler: h.httpServerMux,
 })
}

return overseer.RunErr(overseer.Config{
 Address: address,
 Program: func(state overseer.State) {
 // ...
 http.Serve(state.Listener, nil)
 },
})

func (mp *master) fork() error {
 mp.debugf("starting %s", mp.binPath)
 cmd := exec.Command(mp.binPath)
 //mark this new process as the "active" slave process.
 //this process is assumed to be holding the socket files.
 mp.slaveCmd = cmd
 mp.slaveID++
 //provide the slave process with some state
 e := os.Environ()
 e = append(e, envBinID+"="+hex.EncodeToString(mp.binHash))
 e = append(e, envBinPath+"="+mp.binPath)
 e = append(e, envSlaveID+"="+strconv.Itoa(mp.slaveID))
 e = append(e, envIsSlave+"=1")
 e = append(e, envNumFDs+"="+strconv.Itoa(len(mp.slaveExtraFiles)))
 cmd.Env = e
 //inherit master args/stdfiles
 cmd.Args = os.Args
 cmd.Stdin = os.Stdin
 cmd.Stdout = os.Stdout
 cmd.Stderr = os.Stderr
 //include socket files
 cmd.ExtraFiles = mp.slaveExtraFiles
 if err := cmd.Start(); err != nil {
 return fmt.Errorf("Failed to start slave process: %s", err)
 }
 // ...
}

func main() {
 // 配置初始化
 if err := config.Init(appConf); err != nil {
 fmt.Println(err)
 return
 }
 cfg := config.GetConfig()

 // 初始化graceful http服务
 gracefulHTTPServer := microsvr.GracefulHTTPServer{
 Address: cfg.HTTPListenAddress,
 Conf:  cfg,
 Initialization: initialization,
 HttpServer: httpServer,
 }

 // 启动
 if err := gracefulHTTPServer.Run(); err != nil {
 fmt.Println(err)
 return
 }
}

// 初始化日志、数据库链接、定时任务等
func initialization(cfg *config.Conf) {
 if err := microsvr.Init(cfg); err != nil {
 fmt.Println(err)
 return
 }

 if err := server.AddConnect(cfg.Databases.String()); err != nil {
 fmt.Println(err)
 return
 }
 logger.Info("数据库链接成功：" + cfg.Databases.Address)
 // cron
 cron.Cron.Init()
}

// 初始化http服务，但不启动
func httpServer() *http.Server {
 server := microsvr.NewHTTPServer()
 server.SetAllowOrginBack()
 Routers(server)
 return server
}