Add Dockerflow standard endpoints about blurts-server

[pdehaan]

This may be a decent enough starting point:

"use strict";

const fs = require("fs");
const path = require("path");
const router = require("express").Router();

let commmit;
try {
  commit = require("git-rev-sync").short();
} catch (err) {
  // ignore
}

const { version, homepage } = require("../package.json");

const versionJsonPath = path.join(__dirname, "..", "public", "version.json");
const versionJson = {
  commit,
  source: homepage,
  version,
};

fs.writeFileSync(versionJsonPath, JSON.stringify(versionJson, null, 2) + "\n");

router.get("/__version__", (req, res) => {
  return res.sendFile(versionJsonPath);
});

router.get("/__heartbeat__", (req, res) => {
  return res.send("OK");
});

router.get("/__lbheartbeat__", (req, res) => {
  return res.send("OK");
});

module.exports = router;

This should create a ./public/version.json file which gets generated at startup and then visiting /__version__ will just return that static file. By wrapping it in a try..catch, I think it should also work if the target stage/production server doesn't have Git installed but OPs or somebody manually creates a ./public/version.json file during their build process.

We'd also need to do npm i git-rev-sync -D and add ./public/version.json to the .gitignore.

Or, I'm way off and this is just stupid. 🤷‍♀️