How to check running host and port on Phoenix
If you can't figure out why the web server is running but ingress returns 503 for every single request, try run a bash session in your problematic pod and run this command to get the running configuration for your web endpoint:
Application.get_env(:my_app, MyAppWeb.Endpoint)
You may get some surprising info which exposes that the host and the port isn't matching what's being expected.