User inside docker

I built a Docker image that has a user named “appuser” and this user has a defined uid of 1001. On my test server, the account I’m using is named “marc”, and it also has the uid of 1001. When I start the container, the sleep command executes as appuser, because the Dockerfile contains the line “USER appuser”. But this really doesn’t make it run as appuser, it makes it run as the uid of the user that the Docker images knows as appuser.

https://medium.com/@mccode/understanding-how-uid-and-gid-work-in-docker-containers-c37a01d01cf