Golang net / http服务器处理程序热重载

Question

Is it possible to change the http Server's Handler struct field whilst the Server is running? I have a dynamic list of routes which can change throughout the lifetime of the server, but want to avoid any downtime.

package main

import (
    "log"
    "net/http"
    "time"
)

func main() {
    // construct the handler for the first time
    handler, err := constructHandler()
    if err != nil {
        return nil, err
    }

    // create the server
    s := &http.Server{
        Addr:    ":80",
        Handler: handler,
    }

    // start the server in on a separate goroutine.
    go func() {
        if err := s.ListenAndServe(); err != nil {
            log.Fatalf("unable to start http server: %v", err)
        }
    }()

    // recreate and hot-reload the handler every 30 seconds
    for range time.Tick(30 * time.Second) {
        handler, err = constructHandler()
        if err != nil {
            log.Printf("cannot reload: unable to construct handler: %v", err)
            continue
        }

        // only hot-reload the handler if there wasn't an error
        s.Handler = handler
    }
}

func constructHandler() (handler http.Handler, err error) {
    // handler gets created.
    // this could involve making calls to a database.
    // ...
    return handler, err
}

Answer 1

你这个代码，想切换端口就不能用了；