Can RHEL7 VM run remote libvirt commands to Fedora36 host?

[Martin Kletzander]

On Thu, Jul 28, 2022 at 02:14:30PM -0400, Carol Bouchard wrote:
>I have a test environment that use to work but no longer does. My
>laptop is Fedora36 (libvirt version 8.1.0.2) while the VMs it spawns are
>RHEL7 (max libvirt version is 4.5.0). The source of my problem
>seems to be that RHEL7 libvirt needs rw socket /var/run/libvirt/libvirt-sock
>which no longer exists in fedora36.
>
>The following is successful from RHEL7 VM to laptop:
>virsh -d0 --connect
>'qemu+ssh://192.168.120.1/system?*socket*=/var/run/libvirt/libvirt-sock-ro'
>domstate beaker-test-vm1.beaker
>
>If I change the action from domstate to start, it fails on
>error: Failed to start domain beaker-test-vm1.beaker
>error: operation forbidden: read only access prevents virDomainCreate
>which made me realize ro stands for read-only; however, there is no
>libvirt-sock. I tried some of the other socket files without success.
>Is there a work-around?
>

It is pretty weird that something is listening on the libvirt-sock-ro and not on
libvirt-sock.  Could you run a quick lsof to figure out who's listening on
libvirt-sock?  If it is systemd, then you have socket activation set up for the
read-only socket *only* and you need to also enable libvirtd.socket.  Something
along the lines of:

     systemctl enable --now libvirtd.socket libvirtd-ro.socket
     systemctl stop libvirtd.service

should suffice.

You might also be running in the newer split daemon scenario and you have
virtqemud running instead.  The service listening to libvirt socket might be for
virtproxyd[0] instead and you might need to do the following instead:

     systemctl enable --now virtproxyd.socket virtproxyd-ro.socket
     systemctl stop virtproxyd.service

To make sure try figuring out which systemd service/socket is associated with
the socket, by running `systemctl status libvirtd virtproxyd`.

Martin

[0] https://libvirt.org/manpages/virtproxyd.html
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