---
upgrade:
  - Ironic no longer supports agent lookup/heartbeats as vendor passthru
    methods. All out-of-tree drivers must be updated to use
    ``AgentDeployMixin`` classes directly without relying on
    ``BaseAgentVendor`` class and other classes that were inheriting from it
    (e.g. ``agent.AgentVendorInterface`` and ``iscsi_deploy.VendorPassthru``).

    This means that ironic is incompatible with deploy ramdisks based on Ironic
    Python Agent (IPA) < 1.5.0. Operators must update their IPA-based deploy
    ramdisks in this case. Operators using non-IPA based deploy ramdisks which
    use ironic lookup/heartbeats functionality must update their ramdisks to
    use the top level ironic lookup/heartbeats REST API, available since ironic
    API v1.22.
