Node.js request module can't POST to external URL

Question

I have a web app that collects data from sensors. Sensors send data through POST requests to my webapp at example.com .

For debugging purposes, I need to create an extra layer between the sensors and the webapp.

I have created an extra little webapp that all that does is to take the incoming POST requests to example.com and forward it to the webapp, now responding to a different URL, say example2.com .

So, before it was:

sensors -> example.com (webapp)

now it is:

sensors -> example.com -> example2.com (webapp)

In this way I am able to see what's the webapp response to the sensors and log it.

In order to make this work I have used the request module . Everything works fine when I am testing it on my local machine (my extra layer listens on localhost:3000 and the webapp listens on localhost:3001 ), but as soon as I make it point to an external URL the answer I get back is a 404 Not Found , even though if I POST directly to example2.com everything works as expected.

Here is my module:

var express = require('express');
var app = express();
var request = require('request');
var bodyParser = require('body-parser');
var cuid = require('cuid');
var url = require('url');
app.use(bodyParser.text({ type: '*/*' }));

app.post('/', function (req, res) {

  // immediately send 200 OK to the client
  res.send('ok');

  // add a unique ID
  if (!req.headers['x-request-cuid']) {
    req.headers['x-request-cuid'] = cuid();
  }

  var log_string = req.headers['x-request-cuid'] + "," + new Date().toISOString();

  // filter empty requests
  var reqbody = req.body;
  if(typeof reqbody !== 'string'){
    return res.send('empty body');
  }
  // Configure the request
  var options = {
    method: 'POST',
    url: 'http://example.com', // <- if I put localhost:3001 (the port I put my webapp to listen on) here, it works
    headers: req.headers,
    body: reqbody
  };

  // Start the request
  request(options, function (error, response, body) {

    log_string += "," + new Date().toISOString() + "," + response.statusCode + "," + response.statusMessage + "," + response.body;
    console.log(log_string);
  });

});

app.listen(3000, function () {
  console.log('Example app listening on port 3000!');
});

If it helps, I am working on Google App Engine, so everything gets deployed to Google App Engine.

EDIT: clarification on "does not work"

Answer 1

According to this documentation , your app has to listen to port 8080 .

The App Engine front end will route incoming requests to the appropriate module on port 8080. You must be sure that your application code is listening on 8080.