Re: [libvirt] [RFC] Unify KVM kernel-space and user-space code into a single project
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.
One of the things I'm gonna do post 0.8.0 is allow to bundle comments
and elements from a foreign namespace in the libvirt XML definition.
Currently libvirt will happilly consume such a definition but all the
extra are lost, basically at parse time we just extract the informations
we know about, and everything else is lost. I want to provide clean ways
to add metadata coming from the user and preserve them. I will probably
limit the places where such metadata will be allowed:
1/ to avoid the full complexity of an XML structured editor within
libvirt
2/ to not have to completely modify our configuration reading and
saving code, but add this as an extra layer
3/ to be able to modify the Relax-NG schemas in a reasonnable way
to allow those elements from foreign namespaces
It's not a piece of cake, there will have to be some limitation and
heuristics to avoid the extreme complexity and changes that a full tree
preservation system would requires, but I think that should be
sufficient for your kind of use case,
Daniel
--
Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
daniel(a)veillard.com | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library http://libvirt.org/