Comment 4 for bug 1833542

nova-status upgrade <something> seems like a reasonable place to put it.

I think we only need to wait for nova-compute services, since this seems to be the only one that gets capped.

A very simple implementation could be to replicate the logic here:
 https://github.com/openstack/nova/blob/7ecdee01ed0efcecc4b448118a412d2c6554a27d/nova/compute/rpcapi.py#L412.

It could compare this with the latest version:

https://github.com/openstack/nova/blob/7ecdee01ed0efcecc4b448118a412d2c6554a27d/nova/objects/service.py#L34

Then exit 0 if there is no cap required. The only argument necessary might be something to choose the branch of 'if CONF.api_database.connection:'.

Your suggestion of a report output could be useful for debugging, particularly without an API to determine this information.