How to isolate application code and production configuration?

So I have developed a Phoenix (with Ecto) application as an internal project at my work, and it is nearing time to deploy it.

I would like to keep the repository public and deployment/company agnostic and am wondering if there are any patterns in the community for isolating production configuration from the rest of the application code?

I haven’t yet decided if I will be deploying a release or running it with mix as of yet.


Long read, but worth it: Rethinking app env. If you follow that way, you should be able to provide minimum set of relevant config from outside of the app.