version/main.go

package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
)

const warning = "//WARNING! DO NOT EDIT THIS FILE BY HAND. IT IS AUTO GENERATED.\n"

const header = "package main\nconst gitVersion = \""

const code = `
import (
	"fmt"
	"os"

	"github.com/spf13/pflag"
)

func init() {
	pflag.ErrHelp = nil
	versionFlagSet := pflag.NewFlagSet("version", pflag.ContinueOnError)
	versionFlagSet.ParseErrorsWhitelist.UnknownFlags = true
	versionFlagSet.SetOutput(nil)

	versionIsAsked := versionFlagSet.BoolP("version", "v", false, "Prints version of this application.")
	versionFlagSet.BoolP("help", "h", false, "") // This line is needed to supress (redefine) built-in help flag.

	err := versionFlagSet.Parse(os.Args)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	if *versionIsAsked {
		fmt.Println(gitVersion)
		os.Exit(0)
	}
}

`

func main() {
	cmd := exec.Command("git", "describe", "--tags", "--abbrev=0")
	out, err := cmd.Output()
	if err != nil {
		fmt.Println(err)
		os.Exit(0)
	}
	version := string(out)
	version = version[:len(version)-1]
	content := warning + header + version + "\"" + code

	ioutil.WriteFile("version.go", []byte(content), 0644)
}