[libvirt] [RFC] Unify KVM kernel-space and user-space code into a single project

Daniel P. Berrange berrange at redhat.com
Fri Apr 9 09:17:19 UTC 2010

On Thu, Apr 08, 2010 at 11:27:46PM +0100, Antoine Martin wrote:
> Hi,
> I am moving this thread here as this seems more appropriate.
> Sorry it has taken so long..
> Here are 2 things that really get in the way of moving my existing
> installations to libvirt:
> * I tend to store much meta data with each VM instance: it can be things
> like ownership (contact details as text), monitoring info (sms phone
> numbers), backup (list of paths), firewall rules (custom syntax, with
> failover rules, etc), etc.
> At the moment, these extra bits of information consist of just a few
> optional lines of shell in each VM's definition file. I can extend these
> whenever I need, enumerate the VMs using the standard mechanism and
> trigger my specific actions as needed (firewall rules, backup or whatever).
> I see no way of doing this with libvirt. But please correct me if I am
> wrong.

We fairly recently added a free-form text


element in the domain XML that you can stuff whatever you like into.

The 0.8.0 release will also have support for explicitly managing firewall
rules associated with a VM. It is fairly flexible, so there's a good
chance that it would cope with at least some of your needs there.

> * not everything is exposed via libvirt:
> virsh can retrieve vncdisplay
> but libvirt (or at least the python bindings) does not. How come?
> This happens to be one thing I need for writing a libvirt backend for my
> virtual desktop software.

The 'virsh vncdisplay' command is simply fetching the XML doc for the
guest and then extracting the VNC port using a xpath expression


So for python you'd want to just get an XML handling module and do similar.

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