We are trying to get openstack metrics to Prometheus for further accounting data processing with cloudkitty.
However, when I query prometheus metrics from openstack exporter

openstack_nova_server_status field flavor_id is always returning <nil> in prometheus openstack exporter.

For example:

openstack_nova_server_status{address_ipv4="",address_ipv6="",availability_zone="nova",flavor_id="<nil>",host_id="34473036769974153a388fb747e773fd7aa6095e48c6e23096b105c1",h
ypervisor_hostname="bm-compute01-lm",id="4177d13c-d42b-499c-a917-c76d2dc75226",name="demo-jhtest",status="ACTIVE",tenant_id="960168fa6ffd4b1d8d6007c3f234fa6c",user_id="d4fe
783e96a743fdba7d207b519802c7",uuid="4177d13c-d42b-499c-a917-c76d2dc75226"} 0

It seems that Prometheus is aware of flavors because direct query
curl 'http://prometheus_host:9091/api/v1/label/flavor_id/values
returns list where values correspond to existing flavor ids in OpenStack.

Our OpenStack instance is currently on Wallaby release and is based on Kolla-Ansible.

Looking forward for suggestions or a fix because we really need the flavor_id in downstream accounting processing.