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,