How to use one port for Webpack AND api server for HEROKU?

Hi,

trying to deploy my build to heroku. this repository uses two ports, one webpack and one for api. but as i know, heroku just has one PORT option which gets self assigned with env port variable.

i cannot figure out how to combine the two services. how should i handle this big problem ?

https://myapp.herokuapp.com/ws/?EIO=3&transport=polling&t=LMr9Nni -> 
app[web.1]: [0] proxy error { [Error: connect ECONNREFUSED 127.0.0.1:3030]