[virt-tools-list] [PATCH 22/22] spice: hook into QMP port

[Daniel P. Berrangé]

On Tue, Aug 07, 2018 at 12:52:46PM +0200, Marc-André Lureau wrote:
> Hi
> 
> On Tue, Aug 7, 2018 at 12:01 PM, Daniel P. Berrangé <berrange at redhat.com> wrote:
> > I would suggest it should use libvirt for these actions, but that
> > kind of defeats the goal of what you're trying to achieve by providing
> > a UI that is usable by standalone QEMU.
> >
> > The other thing that occurs to me is that the idea of remote power
> > control is interesting / useful for pretty much all uses of SPICE and
> > VNC with QEMU, even when libvirt is managing QEMU.
> >
> > As it stands we would not want to expose the monitor over SPICE in
> > many cases as it gives the SPICE user way too high privileges, but
> > remote power control is useful especially for cloud users. A way
> > to force a reboot of a dead/hung guest from the SPICE client instad
> > of having to jump out to openstack CLI API for example.
> >
> > In VNC there was a 3rd party extension defined to allow remote power
> > control actions over VNC.
> >
> > Thus I think SPICE could define a remote power control extension of
> > its own that could be safely enabled in all cases, even where the
> > remote user is unprivileged. This is portable to all SPICE server
> > side impls that care to provide it since it would not be QMP.
> 
> If we have to define a new channel, new protocol messages etc, this
> will overlap with what QMP is already providing.
> 
> Qemu or Spice could filter/limit the QMP monitor to a subset of
> commands/events.

Relying on layering QMP over the chardev channel means the entire
thing it essentially opaque from Spice POV. We have virt-viewer
implementing a QEMU protocol directly. Someone who wires up Spice
to a non-QEMU backend may provide a different way to do the same
thing since nothing is standardized as part of Spice.

IMHO spice-server library should provide some callbacks hooks for
power control that QEMU can provide the impl for server side, while
spice-gtk should provide some APIs for power control client side.
virt-viewer shouldn't see a wire protocol at all.

Regards,
Daniel
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