I have a quite the setup (with HAProxy backed by Apache servers, good postgresql server) so I don’t have the need of yet another dependency of nginx.
Question then becomes why is there no container that only has the app itself without nginx? It would simplify things quite a lot as if the ruby and app itself portion is the annoyance most of the time, it wouldn’t be then.
It would simplify things a lot for you.
For a lot of people configuring nginx correctly can be an annoyance as well.
You can always choose to make the simple modification of exposing unicorn to the outside of the containter and have Apache connect to it?
Because the nginx setup that Discourse needs is tightly integrated, quite complex, and might change without warning. It adds very little overhead. They run haproxy on front of their infrastructure, so you will be ok. But if you want, you can remove the web template from your app.yml and try your luck.