How to setup proxy

How To
1 
The app is not listening on the expected address and will not be reachable by fly-proxy.
You can fix this by configuring your app to listen on the following addresses:
  - 0.0.0.0:3000

How can I fix this warning?

2

You should configure your server to listen on 0.0.0.0:3000. What language/framework is your app using?

3

It is using NodeJS

4

Then your code should look something like this:

app.listen(3000);