routes.js

var express = require('express');
var router = express.Router();
const log = require('barelog')
const fs = require('fs')
const { spawn } = require('child_process');
var tmp = require('tmp');
const { urlencoded } = require('body-parser')
const { Readable } = require("stream")

const jbin = process.env.JSONNET_BIN;
const jlib = process.env.JSONNET_LIB;
const jfile = process.env.JSONNET_FILE;

let counter = 0;

router.get('/count', (req, res) => {

  res.status(500).json({ count: counter });

});

router.post('/processRaw', (req, res) => {

  const now = new Date().toISOString().
  replace(/T/, ' ').      // replace T with a space
  replace(/\..+/, '')     // delete the dot and everything after
  + ' UTC';

  res.setHeader('Content-Type', 'application/json');
  return processRequestRaw(req, res, now);
});

router.post('/download', urlencoded(), (req, res) => {

  const now = new Date().toISOString().
  replace(/T/, ' ').      // replace T with a space
  replace(/\..+/, '')     // delete the dot and everything after
  + ' UTC';


  res.setHeader('Content-disposition', 'attachment; filename=microprofile-grafana-dashboard.' + now + '.json');
  res.setHeader('Content-type', 'application/octet-stream');
  processRequestRaw(Readable.from(req.body.metrics), res, now);

});

function processRequestRaw(stream, res, dateStr) {
    const tmpobj = tmp.fileSync();
    var fstream = fs.createWriteStream(null, {fd: tmpobj.fd});

    stream.pipe(fstream);

    const child = spawn(jbin,
      ['-J', jlib,
       '--ext-code-file', 'src=' + tmpobj.name,
       jfile]);


    child.stdout.on('data', (data) => {
      res.write(data.toString().replace(new RegExp(/%TIMESTAMP%/, 'g'), dateStr));
      res.status(200);
    });
    child.stderr.on('data', (data) => {
      res.setHeader('Content-Type', 'text/plain');

      log('child err:' + data.toString());
      res.statusMessage = data.toString().replace(new RegExp(/[^a-zA-Z0-9 ]/, 'g'), ' ');
      log("sending back: " + res.statusMessage);
      res.status(400).end();
    });

    child.stdout.on('error', (data) => {
      res.setHeader('Content-Type', 'text/plain');

      log('child fail:' + data.toString());
      res.statusMessage = data.toString().replace(new RegExp(/[^a-zA-Z0-9 ]/, 'g'), ' ');
      log("sending back: " + res.statusMessage);
      res.status(400).end();

    });

    child.on('exit', function (code, signal) {
      log('child process exited with ' +
                  'code ' + code + ' and signal ' + signal);
      counter++;
      res.status(200);
      res.end();
    });
}


module.exports = router;