Env variables are considered best practice (factor 3): https://developer.ibm.com/articles/creating-a-12-factor-appl...

If I would avoid env then i need to put it in some kind of conf file and configure the app to read this file (e.g. mount into container). If I use a fault then i need some kind of credentials to receive the credentials.

So again what do I gain if I avoid env variables in containers?