Goal:

• Aetos when installed through the devstack plugin creates a keystone endpoint labeled "prometheus". Admins can register a plain prometheus into keystone with a single command too. The observabilityclient should be able to use that to discover the prometheus / aetos endpoint. The current options (/etc/openstack/prometheus.yaml file and env variables) should stay and since they seem a bit more explicit, they should have higher priority (so when a keystone endpoint exists and a /etc/openstack/prometheus.yaml exists as well, the file will be used. When env variable is defined, it'll get used instead of any of the previous two).

Acceptance Criteria:

• A patch to enable observabilityclient discover prometheus or aetos from keystone endpoints exists and is merged.