Open Stack

On 6/20/2015 3:35 PM, Daniel P. Berrange wrote:
> On Sat, Jun 20, 2015 at 01:50:53PM -0500, Matt Riedemann wrote:
>> Waking up from a rare nap opportunity on a Saturday, this is what was
>> bothering me:
>>
>> The proposal in the etherpad assumes that we are just getting bulk
>> host/domain/guest VM stats from the hypervisor and sending those in a
>> notification, but how do we go about filtering those out to only instances
>> that were booted through Nova?
>
> In general I would say that is an unsupported deployment scenario to
> have other random virt guests running on a nova compute node.
>
> Having said that, when nova uses libguestfs, it will create some temp
> guests via libvirt, so we do have to consider that possibility.
>
> Even today with the general list domains virt driver call, we could be
> getting domains that weren't launched by Nova I believe.
>
>> Jason pointed out the ceilometer code gets all of the non-error state
>> instances from nova first [1] and then for each of those it does the domain
>> lookup from libvirt, filtering out any that are in SHUTOFF state [2].
>>
>> When talking about the new virt driver API for bulk stats, danpb said to use
>> virConnectGetAllDomainStats with libvirt [3] but I'm not aware of that being
>> able to filter out instances that weren't created by nova.  I don't think we
>> want a notification from nova about the hypervisor stats to include things
>> that were created outside nova, like directly through virsh or vCenter.
>>
>> For at least libvirt, if virConnectGetAllDomainStats returns the domain
>> metadata then we can filter those since there is nova-specific metadata in
>> the domains created through nova [4] but I'm not sure that's true about the
>> other virt types in nova (I think the vCenter driver tags VMs somehow as
>> being created by OpenStack/Nova, but not sure about xen/hyper-v/ironic).
>
> The nova database hsa a list of domains that it owns, so if you query the
> database for a list of valid UUIDs for the host, you can use that to filter
> the domains that libvirt reports by comparing UUIDs.
>
> Regards,
> Daniel
>

Dan, is virsh domstats using virConnectGetAllDomainStats?  I have 
libvirt 1.2.8 on RHEL 7.1, created two m1.tiny instances through nova 
and got this from virsh domstats:

http://paste.openstack.org/show/310874/

Is that similar to what we'd see from virConnectGetAllDomainStats?  I 
haven't yet written any code in the libvirt driver to use 
virConnectGetAllDomainStats to see what that looks like.

-- 

Thanks,

Matt Riedemann