Heroku is rejecting you binding the port to 3000. Change your mongo.js server code to be
var server = app.listen(process.env.PORT || 3000, function() {
var host = server.address().address
var port = server.address().port
console.log('App listening at http://%s:%s', host, port)
});
the process.env.PORT lets heroku pick its own port.
Heroku is rejecting you binding the port to 3000. Change your mongo.js server code to be
the process.env.PORT lets heroku pick its own port.