Re: Can RHEL7 VM run remote commands to Fedora36 host?

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On Wed, Jul 27, 2022 at 01:18:00PM -0400, Carol Bouchard wrote:
> I have a Fedora36 laptop which hosts VMs with RHEL7 using libvirt.  One of
> the RHEL7 VMs, runs remote commands (as root) to 'start' another VM by
> way of my laptop.  In other words,  the following command is run:
> virsh --connect 'qemu+ssh://' start
> beaker-test-vm1.beaker
> If I run non-remote version of the command on the laptop, it is successful.
> For example,
> virsh --connect qemu:///system start beaker-test-vm1.beaker  <-- Successful
> on laptop.
> If I do a query like the following *(notice socket use)*, it is successful.
> virsh -d0 --connect
> 'qemu+ssh://*socket*=/var/run/libvirt/libvirt-sock-ro'
> domstate beaker-test-vm1.beaker
> Without socket, I get the following error:
> *error: failed to connect to the hypervisor*
> *error: End of file while reading data: Ncat: No such file or directory.:
> Input/output error*
> This does not work for 'start' because I believe this is a read-only socket
> since I see the error:
> error: Failed to start domain beaker-test-vm1.beaker
> error: operation forbidden: read only access prevents virDomainCreate
> When I look at my laptop, there is no /var/run/libvirt/libvirt-sock.
> So.....I've been wondering
> whether RHEL7 virsh/libvirt is compatible with Fedora36.  Is there a
> work-around?  I can't
> change the distros on my laptop or VMs.

since Fedora 35 libvirt has used the modular daemons architecture. What this
means for you (and appears very confusing) is that when you try starting a VM
locally on your F36 laptop, your virsh client doesn't connect to libvirt-sock
anymore, there's a dedicated connection socket for each of the daemons now and
instead will connect to virtqemud-sock.
Now, old virsh clients like the one you have on your RHEL7 don't know about
this and expect to connect to libvirt-sock instead. In order to create that
socket and restore functionality for old clients you need to start and enable
the virtproxyd.socket systemd unit which proxies old client connections to the
new sockets we have. Why the virtproxyd socket isn't running by default unless
you disabled it beats me, since:

$ systemctl status virtproxyd
Loaded: loaded (/usr/lib/systemd/system/virtproxyd.socket; enabled; vendor preset: enabled)

is set correctly after installation.
Anyhow, just do:
$ sudo systemctl enable --now virtproxyd.socket

on your laptop and you're good to go


So, if you don't have the libvirt-sock created that means the virtproxyd.socket
systemd unit isn't active. Just enable the socket and try again.

Here, I simulated it for you with my VMs:

$ cat /etc/os-release
NAME="Fedora Linux"
VERSION="36 (Thirty Six)"


> Carol

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