Dockerfile: chown group error

[jdkent]

Docker version 19.03.12, build 48a66213fe

When building the Docker Image, I got the error (or something close to this error):

unable to convert uid/gid chown string to host mapping: can't find gid for group pliers: no such group

which occurs during COPY --from=builder --chown=pliers /opt/venv /opt/venv because if a group is not specified in --chown, the version of docker I'm using assumes the group is the same as the user (e.g., pliers), but since RUN useradd --no-user-group --create-home --shell /bin/bash pliers specifies that a group should not be added, then the error occurs since the pliers group does not exist.

I can fix it by removing the option --no-user-group, but I do not know what unintended side effects I'm incurring.

@kaczmarj: looks like you wrote those lines, would you know if removing --no-user-group is a bad idea?

[kaczmarj]

@jdkent - to my knowledge, removing --no-user-group should be fine. That syntax comes from neurodocker, where --no-user-group is added to useradd. I might have to take a look at that again and consider removing it... thanks for letting me know.