I am just getting into Express, operating using Cloud Functions and I am caught in an issue. I know that when running on my local machine, I can use:
app.lis
You don't get a dedicated IP address with Cloud Functions. The resolved IP address for your project's functions may change over time. You function may be running on many server instances at the same time, under the control of Cloud Functions.
You can't listen on some port in Cloud Functions. For HTTP type functions, Cloud Functions manages the listening for you, and you just handle the incoming requests.
If you want to write HTTP functions, you should start with the documentation.