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On Tue, Feb 04, 2014 at 01:11:10PM -0800, Dan Smith wrote:
> >> Whats the underlying problem here? nova notifications aren't 
> >> versioned?  Nova should try to support ceilometer's use case so
> >> it sounds like there is may be a nova issue in here as well.
> > 
> > Oh you're far from it.
> > 
> > Long story short, the problem is that when an instance is detroyed,
> > we need to poll one last time for its CPU, IO, etc statistics to
> > send them to Ceilometer. The only way we found to do that in Nova
> > is to plug a special notification driver that intercepts the
> > deletion notification in Nova, run the pollsters, and then returns
> > to Nova execution.
> 
> Doesn't this just mean that Nova needs to do an extra poll and send an
> extra notification? Using a special notification driver, catching the
> delete notification, and polling one last time seems extremely fragile
> to me. It makes assumptions about the order things happen internally
> to nova, right?
> 
> What can be done to make Ceilometer less of a bolt-on? That seems like
> the thing worth spending time discussing...

We don't have to add a new notification, but we have to add some new
datas in the nova notifications.
At least for the delete instance notification to remove the ceilometer
nova notifier.

A while ago, I have registered a blueprint that explains which datas are
missing in the current nova notifications:

https://blueprints.launchpad.net/nova/+spec/usage-data-in-notification
https://wiki.openstack.org/wiki/Ceilometer/blueprints/remove-ceilometer-nova-notifier

Regards, 
-- 
Mehdi Abaakouk
mail: sileht at sileht.net
irc: sileht
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