Deploying a Node.js(+MongoDB) app with Heroku, always Local Port - node.js

Question

I've searched and tried a lot of things, and I can't get my deployment to work.
My node.js app works locally, but doesn't work when deployed on heroku. The problem is the port I'm using, I believe.
In my app.js,I have:
1) a server+port:
var server = require('http').createServer();
var port = process.env.PORT || 5000;
2) The port I want to listen to: (I do think this part is wrong)
server.listen(port, function() {
console.log("Listening on " + port);
});
app.listen(port);
// app.listen(process.env.PORT || 5000);
module.exports = app;
3) And some other stuff
var app = express();
app.use(express.static(path.join(__dirname, 'public')));
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
//app.use(express.static(__dirname + '/'))
// var routes = require('./routes/index');
var routes = require('./routes/index')(passport);
var users = require('./routes/users');
// make db accessible to the router
app.use(function(req,res,next){
req.db = db;
next();
});
app.use('/', routes);
app.use('/users', users);
// app.use('/api', api);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
// error handlers
//development error handler
//will print stacktrace
if (app.get('env') === 'development') {
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: err
});
});
}
// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: {}
});
});
When I'm on my deployed app, and here you can see it says it will redirect to the place I want (at the bottom left)
the frozen-fortress.../login/facebook..etc
however, when i actually click on it, it gives me
localhost:3000/login/facebook...etc
This happens with some of my others links too, but NOT all the links.
What can I do the change the port? I have tried things like app.listen(port) as well.
Thank you in advance! (Also I apologize if the format of my question looks funky, this is my first time on stackoverflow).

Answer 1

I might be wrong, but
look at this part of code:
var server = require('http').createServer();
var port = process.env.PORT || 5000;
// ...
server.listen(port, function() {
console.log("Listening on " + port);
});
app.listen(port);
You create two servers here: server and Express' app. Both will try to listen on the same port and one of them will fail. I mean, Express already has http server inside, you don't need another one:
var port = process.env.PORT || 5000;
app = express()
app.listen(port)
app.use(...)
app.get('/', function(...){
// there you go
})
Here's doc about listen() and other Express things