---
features:
  - |
    Microversion 2.64 is added and enables users to define rules on server
    group policy to meet more advanced policy requirements. This microversion
    brings the following changes in server group APIs:

    * Add ``policy`` and ``rules`` fields in the request of POST
      ``/os-server-groups``. The ``policy`` represents the name of policy. The
      ``rules`` field, which is a dict, can be applied to the policy, which
      currently only supports ``max_server_per_host`` for ``anti-affinity``
      policy.
    * The ``policy`` and ``rules`` fields will be returned in response
      body of POST, GET ``/os-server-groups`` API and GET
      ``/os-server-groups/{server_group_id}`` API.
    * The ``policies`` and ``metadata`` fields have been removed from the
      response body of POST, GET ``/os-server-groups`` API and GET
      ``/os-server-groups/{server_group_id}`` API.