Determine configuration method for CNG containers
Need to spend some time thinking about how to configure the containers at runtime.
Currently I am relying on mounting their existing config files as volumes, and some of the containers, (ie the rails containers) have existing support for some variables being configured via the environment.
This may be good enough (it's enough for our helm charts to easily use)
But it's possible we may want to make things like the external_url easy to configure from the environment variables. This may make the container easier and useful for use in CI in their respective projects.