Heroku is giving me a 503 when trying to open my web app, works on local host

I am trying to deploy to heroku but get a 503 even though it runs on localhost. I am curious as to if my server is set up correctly as I am newer to programming. I hope anyone can point me in the correct direction as to where to look or provide a suggestion as I have spent countless hours on google to this point spanning a couple of weeks.

My main question is if I have set up my server correctly? I am not sure my listener will work for heroku and my .get are used for debugging on localhost when it was initially set up.

Also my full project is available here:

https://github.com/dirkdir/DerekDevSite

var express = require('express');
var app = express();
var path = require('path');


app.use(express.static(path.join(__dirname, 'public')));


app.get('/json', function(req, res) {
    console.log("GET the json");
    res
        .status(200)
        .json( {"jsonData" : true} );
});

app.get('/file', function(req, res) {
    console.log("GET the file");
    res
        .status(200)
        .sendFile(path.join(__dirname, 'app.js'));
});



    var server = app.listen(process.env.PORT || 5000), function() {
        var port = server.address().port;
        console.log("Express is working on port " + port);
});

via Derek Dyer