Go httpserver

//go build -ldflags="-s -w " -trimpath
//go build -ldflags "-s -w -H windowsgui" -trimpath
package main

import (
	"fmt"
	"log"
	"net"
	"net/http"
	"os/exec"
	"runtime"
	"strconv"

	"github.com/gobuffalo/packr"
)

func openbrowser(url string) {
	var err error

	switch runtime.GOOS {
	case "linux":
		err = exec.Command("xdg-open", url).Start()
	case "windows":
		err = exec.Command("rundll32", "url.dll,FileProtocolHandler", url).Start()
	case "darwin":
		err = exec.Command("open", url).Start()
	default:
		err = fmt.Errorf("unsupported platform")
	}
	if err != nil {
		log.Fatal(err)
	}

}
func createListener() (l net.Listener, close func()) {
	l, err := net.Listen("tcp", ":0")
	if err != nil {
		panic(err)
	}
	return l, func() {
		_ = l.Close()
	}
}
func main() {
	l, close := createListener()
	defer close()
	box := packr.NewBox("./static")
	content, _ := box.FindString("template.html")
	http.Handle("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte(content))
	}))
	log.Println("listening at", l.Addr().(*net.TCPAddr).Port)
	openbrowser("http://127.0.0.1:" + strconv.Itoa((l.Addr().(*net.TCPAddr).Port)))
	http.Serve(l, nil)
}