We would like to have a nova-manage command that can take existing quota limits in the nova database and convert/populate them as keystone unified limits.

The idea is to provide an optional tool for operators to help them migrate from legacy quota limits to unified limits. This tooling is not required for operators to use unified limits – they can call the keystone API to set their unified limits however they like.

The command should look for limits in the same order in which they are used by nova for checking quota [1]:

• Project-scoped limits
  • nova_api.quotas (aka "project" limits) => keystone limits
• Default limits
  1. nova_api.quota_classes (aka "default" limits) => keystone registered limits
  2. If there is no nova_api.quota_classes record for a resource:
     • Limits in nova.conf [quota] config options => keystone registered limits

Some approaches:

• nova-manage export limits + keystone-manage import limits
  • can be done entirely offline
• nova-manage calling keystone API to create unified limits from the local nova limits in the database
  • would not require tooling on the keystone side

[1] https://docs.openstack.org/nova/latest/admin/quotas.html