Settings restrictions¶

Plugin functionality can depend on some core features of Fuel or on the features of other plugins. You can provide only some subset of the functionality when some core feature is disabled and, vice versa, the full functionality. You can also provide different functions depending on what kind of hypervisor the user selects. Settings restrictions provide a way to dynamically change the settings provided by a plugin. The general information on the settings restrictions is in Developer Guide -> Extending OpenStack Settings -> Restrictions.

Settings restrictions are defined in environment_config.yaml and can be applied not only to any specific setting but also for a plugin as a whole. In this case, the restrictions should be applied to plugin metadata.

This is an example of using restrictions in Fuel Xenserver plugin:

attributes:
 metadata:
  restrictions:
    - "settings:common.libvirt_type.value == 'kvm'"
    - "settings:storage.volumes_ceph.value == true"
    - "settings:storage.images_ceph.value == true"
    - "settings:storage.ephemeral_ceph.value == true"
    - "settings:storage.objects_ceph.value == true"
    - "settings:additional_components.sahara.value == true"
    - "settings:additional_components.murano.value == true"
    - "settings:additional_components.ceilometer.value == true"
    - "settings:additional_components.mongo.value == true"
    - "settings:additional_components.ironic.value == true"

If any of the listed settings are enabled, then the user cannot enable the plugin. The restrictions are bidirectional, i.e. if you enable the plugin, you cannot enable any of the listed settings without disabling the plugin first.

You can use other entry points to the Fuel API besides settings as context. Some of the valid contexts are networking_parameters, version, and cluster. Settings restrictions are used extensively for the core Fuel settings. To examine them, use the command fuel --env 38 settings --default to download the default settings from one of the existing environments and look for the substring restrictions in the resulting file.