Permissions issue with Docker volumes

Question

I want to start using Docker for my Rails development, so I'm trying to put together a skeleton I can use for all my apps.

However, I've run into an issue with Docker volumes and permissions.

I want to bind-mount the app's directory into the container, so that any changes get propagated to the container without the need to re-build it.

But if I define it as a volume in my docker-compose.yml, I can't chown the directory anymore. I need the directory and all its contents to be owned by the app user in order for Passenger to work correctly.

I read that it's not possible to chown volumes.

Do you know of any workarounds?

Answer 1

You could try to run the chown instead by CMD. Like:

CMD chown -R app:app /home/app/webapp && /sbin/my_init

RUN statements are only executed during built time of your image. But there you do not have mounted volumes, yet.

CMD instead is executed during runtime of the container when the volumes are mounted already. So that would have the effect that you want.