I am working with Docker, and I want to mount a dynamic folder that changes a lot (so I would not have to make a Docker image for each execution, which would be too costly), but I want that folder to be read-only. Changing the folder owner to someone else works. However, `chown` requires `root` access, which I would prefer not to expose to an application. 

When I use `-v` flag to mount, it gives whatever the username I give, I created a non-root user inside the docker image, however, all the files in the volume with the owner as the user that ran docker, changes into the user I give from the command line, so I cannot make read-only files and folders. How can I prevent this? 

I also added `mustafa ALL=(docker) NOPASSWD: /usr/bin/docker`, so I could change to another user via terminal, but still, the files have permissions for my user.