Today we've got the principle of "don't do that," which we've expressed in the docs: https://docs.openstack.org/nova/latest/admin/configuration/schedulers.html#compute-capabilities-as-traits Trying to enforce those principles programmatically beyond what we've already done is going to be tricky, and as long as operators behave and read the docs (even if it's after we've marked their bug report as Invalid with the above link), mork work than benefit. So I'm going to vote "do nothing for now". efried .