[openstack-dev] [Ceilometer] [Metering] BP for new Ceilometer Agent(less) framework ...

Doug Hellmann doug.hellmann at dreamhost.com
Wed Jan 30 18:12:31 UTC 2013

On Wed, Jan 30, 2013 at 8:04 AM, Julien Danjou <julien at danjou.info> wrote:

> On Tue, Jan 29 2013, Sandy Walsh wrote:
> Hi Sandy,
> > https://blueprints.launchpad.net/ceilometer/+spec/new-ceilometer-agent
> >
> > Full spec: http://wiki.openstack.org/NewCeilometerAgent
> >
> > Video walkthrough of the StackTach worker (basis for proposal):
> http://www.youtube.com/watch?v=thaZcHuJXhM
> > (bump resolution and bandwidth, sorry for the um's)
> What you propose is to drop the ceilometer-compute-agent, not the
> central one, you should make this clearer I think.
> Dropping the central one is just not going to happen anytime soon, but
> that doesn't sound like a problem to me for now -- and it doesn't seem
> it's a problem for you too.
> IIUC your blueprint what you want to do is to retrieve data in a push
> model from notifications sent by Nova, rather than polling Nova+libvirt.
> As I already pointed out to you on IRC, this has already been discussed
> back in November, the thread is at:
> http://lists.openstack.org/pipermail/openstack-dev/2012-November/002791.html
> (I imagine you remember since it seems you participated)
> As far as I know, what we have currently in the compute agent is an
> implementation of the result of this thread, and Eoghan did the
> necessary work on abstracting the virt driver etc on our side rather
> than in Nova side.
> Now, if your blueprint is about implementing the necessary components
> into Nova to emit notifications with interesting information that
> Ceilometer wants (e.g. instance CPU or I/O usage) and use them from
> Ceilometer to drop the ceilometer-agent-compute, I don't think anybody
> -- from the Ceilometer side -- will be against this since, IIRC,
> Ceilometer crew were all for moving all the stuff into Nova back then.

I can certainly see nova allowing more notifications with more data for
instances, but I'm not sure they would include some of the other aspects we
want to eventually include about the host machine itself. Perhaps the data
collection being done for the scheduler now can also emit notifications?

> What you may want to do to start is likely to create a blueprint in Nova
> and get it validated. Changing stuff in Ceilometer then isn't likely to
> be a problem; as you know, we already consume a lot of notifications.

The worker processes described in the video sound a lot like the part of
the collector that processes the incoming notifications. I'm not sure
exactly what the new implementation buys us over what is already there. Can
you elaborate on that aspect, too?


> --
> Julien Danjou
> # Free Software hacker & freelance
> # http://julien.danjou.info
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> OpenStack-dev at lists.openstack.org
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