Open Stack

Hello,

I am working on Watcher and we are currently changing how metrics are
retrieved from different datasources such as Monasca or Gnocchi. Because
of this major overhaul I would like to validate that everything is
working correctly.

Almost all of the optimization strategies in Watcher require the cpu
utilization of an instance as metric but with newer versions of
Ceilometer this has become unavailable.

On IRC I received the information that Gnocchi could be used to
configure an aggregate and this aggregate would then report cpu
utilization, however, I have been unable to find documentation on how to
achieve this.

I was also notified that cpu_util is something that could be computed
from other metrics. When reading
https://docs.openstack.org/ceilometer/rocky/admin/telemetry-measurements.html#openstack-compute
the documentation seems to agree on this as it states that cpu_util is
measured by using a 'rate of change' transformer. But I have not been
able to find how this can be computed.

I was hoping someone could spare the time to provide documentation or
information on how this currently is best achieved.

Kind Regards,
Corne Lukken (Dantali0n)