After reading this link Understanding how uid and gid work in Docker containers | by Marc Campbell | Medium my understanding is that the kernel is the sole entity responsible for assigning uid numbers.
Therefore I would expect that running useradd inside a docker container would create a new uid for the newly created container user.
However what I see is that it will start returning uid starting from 1000 which is already existing.
Check existing users and uid’s:
Run docker container interactively
docker run -it archlinux:latest /bin/bash
Check test_user’s uid
cat /etc/passwd | grep test_user
Can someone enlighten me on what is going on?
Edit: Maybe I should add that my host is archlinux as well.