Ngrok is a great tool which creates introspectible tunnels, however its sometimes a pain to tell your app the name of its tunnel, so here we set it via javascript

set_ngrok_env.js

var request = require('request-promise');

request('http://127.0.0.1:4040/api/tunnels')
  .then( function(res){
    var tunnels = JSON.parse(res).tunnels;
    for(var i in tunnels){
      console.log( 'setting NGROK_HOST_'+i+'=' + tunnels[i].public_url);
      process.env['NGROK_HOST_'+i] = tunnels[i].public_url;
    }
});