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Hi, Doug
	As a follow-up for the discussion on nova_notifier yesterday. I checked nova code, seems it support extra information as followed declaration.
    def _notify_about_instance_usage(self, context, instance, event_suffix,
                                     network_info=None, system_metadata=None,
                                     extra_usage_info=None):

So after we have the option #5 library in nova, we can pass the metering result as extra information to the listener in compute.instance.delete.start event. With this changes, I think we don't need the nova_notifier anymore. 

	Background: currently ceilometer provide a nova notification plugin to notify ceilometer when instance being deleted, see more information at https://bugs.launchpad.net/ceilometer/+bug/1005944. Discussed with Doug and possibly we can remove it if nova provides the metering information in the compute.instance.delete.start event notification.

Thanks
--jyh