---
upgrade:

  - A new ``use_neutron`` option is introduced for configuring Nova to
    use Neutron for its network backend. This replaces the deprecated
    ``network_api_class`` and ``security_group_api`` options, which are
    confusing to use and error prone. The default for this new value
    is ``False`` to match existing defaults, however if
    ``network_api_class`` and/or ``security_group_api`` are set to
    known Neutron values, Neutron networking will still be used as
    before. Installations are encouraged to set this config option soon
    after upgrade as the legacy options will be removed by the Newton
    release.

deprecations:

  - Deprecate ``volume_api_class`` and ``network_api_class`` config
    options. We only have one sensible backend for either of
    these. These options will be removed and turned into constants in
    Newton.