Is this the correct way to terminate a goroutine in golang?

Question

I am building a command line app which needs to start its own HTTP server. My idea is to start the http server inside a goroutine in my main program like this:

func main() {
    go myserver()

    // perform lots of time-consuming tasks
}

func myserver() {
    s := &http.Server{
        Addr: ":8080",
        Handler: MyHandler{},
    }
    log.Fatal(s.ListenAndServe())
}

1. My main function needs to be able to tell the goroutine to die. Since the webserver is blocking on the ListenAndServe method, there is no way of signalling via a sync.WaitGroup or a channel.
2. One idea I have is to make a HTTP POST to the webserver and ask it to commit suicide on receiving a specific agreed-upon value.

Are there other alternatives that are idiomatic to golang ?

Answer 1

If you are running the web interface until the program exits, you can just return from the main thread. Returning from the main thread exits the program even if another goroutine is working. If you want the main thread to send a kill to the http server, the best way is to close the listener.

func main() {
    l, err := net.Listen("tcp", ":8080")
    if err != nil {
        log.Fatal(err)
    }
    go myserver(l)

    // perform lots of time-consuming tasks

    l.Close()
}

func myserver(l net.Listener) {
    s := &http.Server{
        Addr:    ":8080",
        Handler: MyHandler{},
    }
    log.Print(s.Serve(l))
}

This will not close connections already open. It will only prevent new ones from being created. You need to add logic to your handler and/or stop keep-alives to ensure that the connection isn't reused for long after you kill listener.