stop server without exiting program golang

Question

I am using golang to run a simple server on http://localhost:8080. I need a way to stop the server and restart a different server when a user accesses http://localhost:8080/winrestart. So far I have this:

package main


import (
  "net/http" //serving files and stuff
  "log"      //logging that the server is running and other stuff
  "fmt"      //"congrats on winning!"
)


func main() {

  //servemux
  srvmx := http.NewServeMux()

  //handlers that serve the home html file when called
  fs := http.FileServer(http.Dir("./home/"))
  os := http.FileServer(http.Dir("./lvlone/"))
  ws := http.FileServer(http.Dir("./win/"))

  //creates custom server
  server := http.Server {
    Addr: ":8080",
    Handler: srvmx,
  }

  //handles paths by serving correct files
  srvmx.Handle("/", fs)
  srvmx.Handle("/lvlione/", http.StripPrefix("/lvlione/", os))
  srvmx.Handle("/win/", http.StripPrefix("/win/", ws))
  srvmx.HandleFunc("/winrestart/", func(w http.ResponseWriter, r *http.Request){
    fmt.Println("server is being closed")

    //creates new servemux
    wsm := http.NewServeMux()

    //this handler just redirects people to the beggining
    rh := http.RedirectHandler("http://127.0.0.1:8080/", 308)

    //create new redirect server
    redirector := http.Server {
      Addr: ":8080",
      Handler: wsm,
    }

    //Handle all paths by redirecting
    wsm.Handle("/lvlione/", rh)
    wsm.Handle("/win/", rh)
    wsm.Handle("/winrestart/", rh)

    //logs redirect server is Listening
    log.Println("redirecting...")
    server.Close()
    redirector.ListenAndServe()
  })

  //logs that server is Listening
  log.Println("Listening...")
  //starts normal level server
  server.ListenAndServe()
}

As of now, the server closes and the program exits, but no new server is started. Is there a way this can be done?

This has already been answered here: stackoverflow.com/questions/39320025/… — ShrimpPhaser
– ShrimpPhaser, Commented Jul 22, 2018 at 18:38
There are packages for graceful restart already, such as facebookgo/grace. Don't reinvent the wheel. — Michael Hampton
– Michael Hampton, Commented Jul 22, 2018 at 19:24
@MichaelHampton like this? if OP is starting with Go it may be useful to reinvent everything for their own sake. — Kyslik
– Kyslik, Commented Jul 22, 2018 at 19:37
@ShrimpPhaser I tried using the Close function but it closes the program — Person Person
– Person Person, Commented Jul 23, 2018 at 19:06

Zak · Accepted Answer · 2018-07-23 10:33:43Z

1

The problem here is that the main thread becomes unblocked when you call server.Close()

The main thread starts the server on it's very last line: server.ListenAndServe() but when the /winrestart/ handler method gets called; this handler method calls server.Close(), which stops the server, and the original blocking call to server.ListenAndServe() becomes unblocked. The main goroutine exits, and the program exits.

Runnable, simplified example showing this:

https://play.golang.org/p/RM1uNASBaC1

answered Jul 23, 2018 at 10:33

Zak

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