Retrieve App Engine Version name from local git information in Pure JavaScript or in Pure Go

gvn.go

package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/go-git/go-git/v5"
)

// Equivalent of git show -s --abbrev=12 --format=%cd-%h HEAD
// --date=format:'%y%m%d-%H%M'
// Wed Jul 29 22:18:29 2020 -0700 53a7c033dc4f8f10f3122f03b5dd22cc7ec2fadf
// 202907-2218-53a7c033dc4f
func main() {

	var repoPath string
	if len(os.Args) < 2 {
		var pathErr error
		repoPath, pathErr = os.Getwd()
		CheckIfError(pathErr)
	} else {
		repoPath = os.Args[1]
		CheckArgs("<repoPath>")
	}

	repo, err := git.PlainOpen(repoPath)
	CheckIfError(err)
	appEngineFormat, formatErr := GetAppEngineVersionFromRepository(repo)
	CheckIfError(formatErr)
	fmt.Println(appEngineFormat)
}

// Retrieves the HEAD commit date and sha1 information formatted as YYMMDD-HHMM-gggggggggggg
func GetAppEngineVersionFromRepository(
	repository *git.Repository,
) (string, error) {
	headRef, err := repository.Head()
	if err != nil {
		return "", err
	}
	headSha := headRef.Hash().String()

	commit, commitErr := repository.CommitObject(headRef.Hash())
	if commitErr != nil {
		return headSha, commitErr
	}

	when := commit.Committer.When
	format := "060102-1504-"
	datetimeString := when.Format(format)

	return datetimeString + headSha[0:12], nil
}

// CheckIfError should be used to naively panic if an error is not nil.
func CheckIfError(err error) {
	if err == nil {
		return
	}

	fmt.Printf("\x1b[31;1m%s\x1b[0m\n", fmt.Sprintf("error: %s", err))
	os.Exit(1)
}

// CheckArgs should be used to ensure the right command line arguments are
// passed before executing.
func CheckArgs(arg ...string) {
	if len(os.Args) < len(arg)+1 {
		Warning("Usage: %s %s", os.Args[0], strings.Join(arg, " "))
		os.Exit(1)
	}
}

// Warning should be used to display a warning
func Warning(format string, args ...interface{}) {
	fmt.Printf("\x1b[36;1m%s\x1b[0m\n", fmt.Sprintf(format, args...))
}

gvn.js

const fs = require("fs");
const git = require("isomorphic-git");


// Equivalent of git show -s --abbrev=12 --format=%cd-%h HEAD --date=format:'%y%m%d-%H%M'
// PARAMETERS - CHANGE THESE FOR YOUR CODE
const dir = ".";

(async () => {
  const commits = await git.log({ fs, dir, depth: 1, ref: "HEAD" });

  let lastSHA = null;
  let lastTimestamp = null;
  const commitsThatMatter = [];
  for (const commit of commits) {
    lastSHA = commit.oid;
    lastTimestamp = commit.commit.committer.timestamp;
  }
  console.log(
    dateFormat(new Date(lastTimestamp * 1000)) + lastSHA.substring(0, 12)
  );
})();

const pad = (amount) => `00${amount}`.slice(-2);

const dateFormat = (date) => {
  yy = date.getFullYear();
  mm = 1 + date.getMonth();
  dd = date.getDate();
  HH = date.getHours();
  MM = date.getMinutes();
  return `${pad(yy)}${pad(mm)}${pad(dd)}-${pad(HH)}${pad(MM)}-`;
};