Go web starter

web.go

package main

import (
	"net/http"
	"fmt"
	"log"
	"flag"
	"net"
	"time"
	"runtime"
	"os/exec"
)

var (
	httpListen  = flag.String("http", "127.0.0.1:8080", "host:port to listen on")
	openBrowser = flag.Bool("openbrowser", false, "open browser automatically")
)

func viewHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "Helllo World!")
}

func main() {

	host, port, err := net.SplitHostPort(*httpListen)
	if err != nil {
		log.Fatal(err)
	}
	httpAddr := host + ":" + port

	http.HandleFunc("/", viewHandler)

	go func() {
		fmt.Println("Started")
		url := "http://" + httpAddr
		if waitServer(url) && *openBrowser && startBrowser(url) {
			log.Printf("A browser window should open. If not, please visit %s", url)
		} else {
			log.Printf("Please open your web browser and visit %s", url)
		}
	}()
	log.Fatal(http.ListenAndServe(httpAddr, nil))
}

// waitServer waits some time for the http Server to start
// serving url. The return value reports whether it starts.
func waitServer(url string) bool {
	tries := 20
	for tries > 0 {
		resp, err := http.Get(url)
		if err == nil {
			resp.Body.Close()
			return true
		}
		time.Sleep(100 * time.Millisecond)
		tries--
	}
	return false
}

// startBrowser tries to open the URL in a browser, and returns
// whether it succeed.
func startBrowser(url string) bool {
	// try to start the browser
	var args []string
	switch runtime.GOOS {
	case "darwin":
		args = []string{"open"}
	case "windows":
		args = []string{"cmd", "/c", "start"}
	default:
		args = []string{"xdg-open"}
	}
	cmd := exec.Command(args[0], append(args[1:], url)...)
	return cmd.Start() == nil
}