[nova] Applying custom policies at VM creation time

Hello

I'd like to reject VM creation or mutate the request depending on custom (business) logic

for example

- reject duplicate names within the same neutron network(s) - change the VM name to append a number or increase it (VM-1 requested, VM-1 already exists so it gets created as VM-2) - reject some values for particular keys on metadata (role=db rejected for project foo)

How can I accomplish this? I really don't want to patch nova

thanks

PS: I found https://github.com/roaet/wafflehaus but it looks it hasn't been touched in years