Possible duplicate of Do Docker Hub image repositories contain the environment variables from .env file?. Opening anyways as it doesn't look like there has been a definitive answer.
So I've written a docker setup made of different processes with docker-composer. The docker-compose.yml file injects environment variables from an uncommitted .env file. Since the build takes a while, my colleagues asked me to upload prebuilt containers + volumes for the project. I'm wondering wether the .env variables from my machine will be saved into the backups or, as I would expect, they wont and they will need to set their own environment variables (eg. secret api keys and such).
Unfortunately I couldn't find a concise explanation and manually inspecting the backups doesn't seem like a foolproof method to verify no sensitive data is committed.