helper-server.js

var http = require('http')
var fs = require('fs')
var server = http.createServer(function(request, response) {
  var req = request
  response.writeHead(200, {'Content-Type': 'textplain'})
  if (req.method === 'POST') {
    var body = ''
    req.on('data', function(data) {
      body += data
    })
    req.on('end', function() {
      console.log('Body: ' + body)
      fs.writeFile(`/tmp/android-timings/${new Date().toISOString()}.json`, body, function(err, data) {
        if (err) {
          console.log('err writing', err)
        }
      })
    })
    response.writeHead(200, {'Content-Type': 'text/html'})
    response.end('post received')
  }

  response.end('Undefined request .')
})