Description of problem: For some reason this was included in nova::compute and nova::scheduler but never included in nova::api eventhough bug #1529065 specifically calls out the fact that it is missing. Looking at the code - nova-api definitely requires it. E.g the server create request handler sets the target AZ to CONF.default_schedule_zone if none https://github.com/openstack/nova/blob/stable/queens/nova/api/openstack/compute/servers.py#L486 and the az request handler skips the internal_service_availabily_zone when listing AZs https://github.com/openstack/nova/blob/stable/queens/nova/api/openstack/compute/availability_zone.py#L38 nova-conductor also requires it as it calls availability_zones.get_host_availability_zone which defaults to CONF.default_availability_zone
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHEA-2020:0283