features:
  - |
    New configuration options ``[quota]unified_limits_resource_strategy`` and
    ``[quota]unified_limits_resource_list`` have
    been added to enable operators to specify a list of resources that are
    either required or ignored to have registered limits set. The default
    strategy is ``require`` and the default resource list contains ``servers``.
    The configured list is only used when ``[quota]driver`` is set to the
    ``UnifiedLimitsDriver``.

    When ``unified_limits_resource_strategy = require``, if a resource in
    ``unified_limits_resource_list`` is requested and has no registered limit
    set, the quota limit for that resource will be considered to be 0 and all
    requests to allocate that resource will be rejected for being over quota.
    Any resource not in the list will be considered to have unlimited quota.

    When ``unified_limits_resource_strategy = ignore``, if a resource in
    ``unified_limits_resource_list`` is requested and has no registered limit
    set, the quota limit for that resource will be considered to be unlimited
    and all requests to allocate that resource will be accepted. Any resource
    not in the list will be considered to have 0 quota.

    The options should be configured for the :program:`nova-api` and
    :program:`nova-conductor` services. The :program:`nova-conductor` service
    performs quota enforcement when ``[quota]recheck_quota`` is ``True`` (the
    default).

    The ``unified_limits_resource_list`` list can also be set to an empty list.
upgrade:
  - |
    When the ``[quota]driver`` configuration option is set to the
    ``UnifiedLimitsDriver``, a limit of ``-1`` in Keystone will now be
    considered as unlimited and the ``servers`` resource will be considered to
    be required to have a registered limit set in Keystone because of the
    values for ``[quota]unified_limits_resource_strategy`` and
    ``unified_limits_resource_strategy``.