how to add cpu_util to metric list?

I am trying to setup autoscale stack using open stack. I am having problem reading cpu_util value from the instances.

Error:

Feb 26 07:21:43 rgupta-op-stack ceilometer-polling[8197]: 2019-02-26 07:21:43.146 8476 DEBUG ceilometer.compute.pollsters [-] 6e982e28-4cb4-42b2-b608-be4ec4ce1d35/cpu_util volume: Unavailable _stats_to_sample /opt/stack/ceilometer/ceilometer/compute/pollsters/__init__.py:113
Feb 26 07:21:43 rgupta-op-stack ceilometer-polling[8197]: 2019-02-26 07:21:43.146 8476 WARNING ceilometer.compute.pollsters [-] cpu_util statistic in not available for instance 6e982e28-4cb4-42b2-b608-be4ec4ce1d35: NoVolumeException

rgupta@rgupta-op-stack:~$ openstack --version
openstack 3.17.0

rgupta@rgupta-op-stack:~$ openstack metric list | grep cpu
| 70b2d180-6902-42b7-abaf-e34f89aafd2e | ceilometer-low | cpu | ns | 6e982e28-4cb4-42b2-b608-be4ec4ce1d35 |
| fa3239df-9bfe-4cf4-a267-106f23fbcb0b | ceilometer-low | vcpus | vcpu | 5fce3174-40ab-484d-8da1-6ccbc8017cc6 |

How do I add a new metric cpu_util to this list? Can someone point to a documentation with example.
I have read through the metrics.yaml documentation but not sure how to see the parameters that are part of payload?

Thanks
Rahul