[foobar33333]

>You should never login to the shell of a container for config

I absolutely do this and think it works great. Fedora has built a tool called "toolbox" which is basically a wrapper on podman which can create and enter containers where you can install development tools without touching your actual OS.

I basically do all of my development inside a container where the source code is volume mounted in but git/ruby/etc only exist in the container.

This has the benefit of letting me very quickly create a fresh env to test something out. Recently I wanted to try doing a git pull using project access tokens on gitlab and containers let me have a copy of git which does not have my ssh keys in it.

This is somewhat of an edge case though, for a server deployment, yes you shouldn't rely on anything changed inside the container and should use volume mounts or modify the image.