cannot app.get('foo') (Express/Node JS)

I am currently working on adding a real-time chat into a particular website. I am using Express JS package and the initialization information (i.e. start/listen server, etc.) is located in 'www/bin' (by default).

So, this is my init file (i.e. 'www/bin'):

 /**
 * Module dependencies.
 */

var app = require('../app');
var debug = require('debug')('nodeblog:server');
var http = require('http');

/**
 * Get port from environment and store in Express.
 */

var port = normalizePort(process.env.PORT || '3000');
app.set('port', port);

/**
 * Create HTTP server.
 */

var server = http.createServer(app);

/**
  * Listen to Sockets
  */
var io = require('socket.io').listen(server);
app.set('socketio', io); // FIXME: Cannot app.get('socketio') w/out req


/**
 * Listen on provided port, on all network interfaces.
 */

server.listen(port);
server.on('error', onError);
server.on('listening', onListening);

And the thing is that I cannot 'get' this SocketIO declaration as I need in one of the router files to exchange messages between client/server.

Here is this route file:

var express = require('express');
var router = express.Router();
var app = express();
// Models
var auth = require('../models/auth');

var io = app.get('socketio');

router.get('/', auth.ensureAuthenticated, function(req, res, next) {
  res.render('chat', {
    title: 'Chat'
  });
});

io.on('connection', function(socket){
  console.log('a user connected');

  socket.on('chat message', function(msg) {
    io.emit('chat message', msg);
  });

  socket.on('disconnect', function(){
    console.log('user disconnected');
  });
});

module.exports = router;

So, when I try to app.get('socketio)' it returns undefined

Do you know how do I need to correctly declare this app.get('socketio',io) so that I can access it anywhere (but not into the request methods)

via alwaysone