Problems installing libvirt on centos-bootc

[spmfox]

Hello - I'm sorry if this is not the correct place to report this problem. I don't think this is a problem regarding bootc itself, but rather how the container image is working. I am trying to create a hypervisor bootc image, nothing fancy just kvm/libvirt on top of centos-bootc - however the resulting libvirt installation is broken.

To reproduce this:

host# podman run --rm -d quay.io/centos-bootc/centos-bootc:stream9 /bin/bash
container# dnf install -y libvirt

Results in:

  Running scriptlet: libvirt-daemon-driver-qemu-10.0.0-7.el9.x86_64                                                                   79/80 
useradd: group 'kvm' does not exist

  Installing       : libvirt-daemon-driver-qemu-10.0.0-7.el9.x86_64                                                                   79/80 
warning: user qemu does not exist - using root

This does not fail though, and if you build a bootc container with libvirt it will succeed however kvm/libvirt will be broken in several places due to the qemu user being missing. I think I can workaround this, if I can figure out exactly what users/groups need to be created and if any directories need to be chown'ed - but I have not had success yet.

Digging into this, trying to create the user manually results in:

container# groupadd kvm
groupadd: group 'kvm' already exists

So it looks like the group exists already, its referenced in /lib/group. I'm not familiar enough with how this altfile structure works but it looks like the installer for libvirt doesn't understand it.

Thanks in advance for the assistance.

[shi2wei3]

coreos/fedora-coreos-tracker#155

[spmfox]

I took another look at this thinking perhaps the problem is easier than I originally thought.

https://containers.github.io/bootc/filesystem.html?highlight=merge#etc
https://docs.fedoraproject.org/en-US/packaging-guidelines/UsersAndGroups/

After reading the bootc manual again, and better understanding the 3-way merge, I realized the error was misleading. The /real/ issue was that the qemu user was missing, and it could not be created because the group already existed (in /lib/group). So based on the Fedora reference of static UIDs, and seeing the GID matched and was already defined, I simply added this to my build process (before libvirt install):

echo "qemu:x:107:107:qemu user:/:/sbin/nologin" >> /etc/passwd

And that completely solved the problem for me. I think I understand now why all those users and groups are predefined - so I'm not sure why the qemu user was missing but the group was not - either way this solved it for me.