A question about this bug:
https://bugs.launchpad.net/ceilometer/+bug/1061817

In the billing program we are currently writing we've partly accounted for resetting of values in a given period for the cumulative metrics, but since we need high accuracy especially for metrics like network.incoming/outgoing, we are likely to lose chargeable data if someone resets a VM, or a VM goes down.

example:
10min pipeline interval, a reset/shutdown happens 7 mins after the last poll. The data for those 7 mins is gone. Even terminating a VM will mean we lose the data in that last interval.

Fixing the bug so resets don't happen is likely a lot of work, and I have a feeling will require work in Nova, and probably won't account for the terminate case.

On the other hand, would it be possible to setup a notification based metric that updates cumulative metrics, or triggers a poll right before the reset/shutdown/suspension/terminate, so we have an entry right before it resets and don't lose any data? This would pretty much solve the issue, and as long as it is documented that the cumulative metrics reset, this would solve most problems.

Since the 'process_notification' function only gets passed a 'message', I don't know if there is a way to pull the needed data out from nova using only what is in the message though.

Any thoughts, or suggestions as to where to start experimenting?

-Adrian Turjak


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