The Dockerfiles for minion has the instructions to create a user called minion. This user is identified inside /etc/passwd with UID 997.
At runtime, the UID of the main process is 1001, and for consistency, it should be 997. Alternatively, creating the minion user to have UID 1001 would work as well.
Also, it would be useful and more professional to copy the /etc/skel/ files to /opt/minion to have a better prompt when accessing the container.