[yebyen]

> you need to have your CM tool or whatever other supporting files/scripts installed in the image

This pattern is maybe even more helpful than harmful, for making your dev environment more closely match production, when your final deploy target is not a docker container.

(You are obviously going to want to see those build scripts running in test, if not earlier; certainly once, before they should kick off in a production environment.) You could do more individual steps in the docker file, just like you could store your token credentials and database handles in the git repository. Neither way is "completely wrong" but there is a trade-off.