make.go

// +build ignore

// Builds Gohai with version information
package main

import (
	"fmt"
	"log"
	"os"
	"os/exec"
	"strings"
	"time"
)

func commandOutput(name string, args ...string) string {
	out, err := exec.Command(name, args...).Output()
	if err != nil {
		log.Fatal(err)
	}

	return strings.TrimSpace(string(out))
}

func main() {
	gobin := "go"
	if len(os.Args) > 1 {
		gobin = os.Args[1]
	}

	date := time.Now().Format(time.UnixDate)
	commit := commandOutput("git", "rev-parse", "--short", "HEAD")
	branch := commandOutput("git", "rev-parse", "--abbrev-ref", "HEAD")
	go_version := commandOutput(gobin, "version")

	// NB: Starting from Go 1.5, the syntax of these ldflags changes from `-X main.var 'value'` to `-X 'main.var=value'`
	// For reference see https://github.com/golang/go/issues/12338
	ldflags := fmt.Sprintf("-X main.buildDate '%s' -X main.gitCommit '%s' -X main.gitBranch '%s' -X main.goVersion '%s'", date, commit, branch, go_version)

	cmd := exec.Command(gobin, "build", "-a", "-ldflags", ldflags, "gohai.go")
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	err := cmd.Run()
	if err != nil {
		os.Exit(1)
	}
}