Minimize the image size of RHEL-based containers

[vkhodygo]

The base image I download using wwctl container import docker://ghcr.io/warewulf/warewulf-rockylinux:9 rocky-9.5 --syncuser is 940.0 MiB, but we could do better by dropping dnf/yum and using microdnf like here: https://github.com/krestomatio/container_builder/blob/master/rocky/rocky9-minimal/Dockerfile

In the context of bare-metal HPC configurations having system-wide python or any other interpreter pre-installed on compute nodes leads to user confusion; it also takes a noticeable amount of space/memory.

[mslacken]

Although the SUSE images are smaller, see

wwctl image list -s
IMAGE NAME  NODES  SIZE
----------  -----  ----
leap15.6    4      589.1 MiB
rocky9      0      855.0 MiB

and contain no python, they are still nearly 600Mb big due to the fact they include a lot of kernel drivers like the rocky image.
You can still can delete these drivers form the image, if you know your hardware doesn't need them.

[vkhodygo]

You can still can delete these drivers form the image, if you know your hardware doesn't need them.

Neat, I'll take a look. Still, that's about 30% less space without python that's needed only for one package.