make a build.json with git history.

write-build.js

#!/usr/bin/env node
"use strict";

var child_process = require("child_process");
var fs = require("fs");
var path = require("path");
var strftime = require("strftime");
var util = require("util");

var pjson = JSON.parse(fs.readFileSync("package.json", "utf8"));

function main(argv) {
  getGitHistory(function (history) {
    var build = {};
    build.version = pjson.version;
    build.history = history;
    build.date = strftime("%Y-%m-%d %H:%M:%S %Z", new Date());
    build.timestamp = Math.floor(Date.now() / 1000);

    fs.writeFileSync("./build.json", JSON.stringify(build, null, 2));
  })
}

function getGitHistory(callback) {
  child_process.exec("git log --decorate --oneline HEAD~10..HEAD", function (error, stdout, stderr) {
    if (error) {
      console.log("Couldn't get 10 commits: " + stderr);
      // sometimes there aren't enough commits, and git will explode. just use all commits then.
      child_process.exec("git log --decorate --oneline", function (error, stdout) {
        if (error) {
          console.log("Error running git log: " + error.stack);
          process.exit(1);
        }
        return callback(stdout);
      });
    } else {
      return callback(stdout);
    }
  });
}

main(process.argv.slice(2));