How can you run multiple applications on one BEAM instance with MainProxy?

You probably don’t have this part in your config/runtime.exs:

config :main_proxy,
  server: true,
  http: [
    port: 8080,
    ip: {0, 0, 0, 0}
  ],
  # ...

Change the port accordingly.

Hey @stefanluptak thanks for the suggestion. I had port already in config/config.exs and I’ve added ip (tried them in both config.exs and runtime.exs), but I’m still running into the same error logs.

Two suspects:

1. Are you starting MyApp.Proxy (or whatever you called it) in your application.ex in the supervision tree? This is this step in the readme:

children = [
  # ... other children
  MyApp.Proxy,
]

This should be done in one of the applications you have in app/. In my case I created a separate application just to serve that.

2. Are you including and starting the application mentioned in the paragraph above (may be your “ui” or “web” app too if you don’t use dedicated one for proxy) in the release configuration?

You should have something like this in the top-level mix.exs of your project

deps: deps(),
releases: releases()
...

defp releases do
  [
    my_app: [
      applications: [
         proxy: :permanent
         ...
       ]
    ]
  end

I strongly suspect you’re not doing 1 or 2 or both and the OTP application that should have main proxy as a child either does not start at all, or does not start the child.

I am also suspecting not exposing ports in Docker, if it is being used.

Hey @hubertlepicki thanks! #2 fixed the release locally and I’m now seeing the other two apps when I start it. The app deployed correctly and I’m no longer seeing the No open HTTP ports detected logs. Unfortunately the admin apps still aren’t being served according to the backends I defined in MyApp.Proxy. What could I be doing wrong there?

I’m not using Docker.

Do you include these admin apps in the release as well? They both should have entries with :permanent just like your main app does.

Yea one entry for the main app, one each for the admin apps, and now one for the proxy app.

And it’s broken as well on the local release and when you deploy, or only when you deploy?

But it works when you start with iex -S mix ?

Also: what does it mean it’s broken. It renders 404 page out of the main app?

Only when I deploy. The local release is starting normally and I can access the admin apps from the domains defined in backends. On the deployed version I’m seeing a “This site can’t provide a secure connection my-shop-admin.my-app-lhrl.onrender.com uses an unsupported protocol.” page (ERR_SSL_VERSION_OR_CIPHER_MISMATCH). It doesn’t actually produce a log with more information.