---
upgrade:
  - |
    The ``NovaHWMachineType`` parameter now defaults ``x86_64`` based instances
    to the unversioned ``q35`` machine type. The remaining architecture machine
    type defaults being provided directly by OpenStack Nova.

    A ``environments/nova-hw-machine-type-upgrade.yaml`` environment file has
    been provided to pin ``NovaHWMachineType`` to the previous versioned
    machine type defaults during an upgrade.

    When the upgrade of the overcloud is complete the following OpenStack Nova
    documentation should then be used to ensure a machine type is recorded for
    all existing instances before the new ``NovaHWMachineType`` default can be
    used in the environment.

    https://docs.openstack.org/nova/latest/admin/hw-machine-type.html#update