Add periodic task to volume manger to report vol existance

[Ollie Leahy]

A periodic task is required in cinder/volume/manager.py to send audit notifications that volumes exist. So that operators can bill by volumes available as well as IO traffic to cinder volumes.

The periodic task could be modelled on the function _poll_volume_usage() in nova/compute/manager.py

[John Griffith (john-griffith)]

I'm not crazy about polling at this scale, I'd rather see an implementation of this via ceilometer, or even just provide the filters you need from the API and let the service provider decide how/when to use it that way.

Also as far as I can tell, the method you reference in nova is actually a dead method (grep doesn't show anything as calling it).

[Mike Perez (thingee)]

+1 ceilometer.

[Ollie Leahy (oliver-leahy-l)]

You're right that the function _poll_volume_usage() is never explicitly called, but because it has the decorator @periodic_task the manager class calls it every 'cycle of the periodic scheduler'.

_poll_volume_usage() is not a dead function, if it is enabled by setting volume_usage_poll_interval to a non zero value you will see logs from that function in the nova compute.log file.

While the ceilometer might be the correct way to go longer term it doesn't make sense to me that users should use two such different ways to get notifications for volume io usage and volume capacity usage.

[John Griffith (john-griffith)]

Right, sorry about my confusion on the decorator... but regardless.

I'm not crazy about adding this especially now that we're trying to get RC1 out. To clarify on the API call/filters, what I'm suggesting is an API call or extension that gives an admin the ability to pull this data if/when they want and to pull it with more or less details etc. Adding the ability to filter the results on specific parameters.

I believe this would solve your dilema as well as provide an interface for ceilometer to use. We'd need this for multiple things, not just volumes. I think it deserves some thought and design and not just thrown in at the last minute.