Neutron shared routines and utilities.
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neutron-lib/neutron_lib/api/extensions.py

269 lines
9.5 KiB

# Copyright 2011 OpenStack Foundation.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import abc
import six
from neutron_lib._i18n import _
from neutron_lib import constants
_UNSET = constants.Sentinel()
def is_extension_supported(plugin, alias):
"""Validate that the extension is supported.
:param plugin: The plugin class.
:param alias: The alias to check.
:returns: True if the alias is supported else False.
"""
return alias in getattr(plugin, "supported_extension_aliases", [])
@six.add_metaclass(abc.ABCMeta)
class ExtensionDescriptor(object):
"""Base class that defines the contract for extensions."""
@abc.abstractmethod
def get_name(self):
"""The name of the extension.
e.g. 'Fox In Socks'
"""
@abc.abstractmethod
def get_alias(self):
"""The alias for the extension.
e.g. 'FOXNSOX'
"""
@abc.abstractmethod
def get_description(self):
"""Friendly description for the extension.
e.g. 'The Fox In Socks Extension'
"""
@abc.abstractmethod
def get_updated(self):
"""The timestamp when the extension was last updated.
e.g. '2011-01-22T13:25:27-06:00'
"""
# NOTE(justinsb): Not sure of the purpose of this is, vs the XML NS
def get_resources(self):
"""List of extensions.ResourceExtension extension objects.
Resources define new nouns, and are accessible through URLs.
"""
return []
def get_actions(self):
"""List of extensions.ActionExtension extension objects.
Actions are verbs callable from the API.
"""
return []
def get_request_extensions(self):
"""List of extensions.RequestExtension extension objects.
Request extensions are used to handle custom request data.
"""
return []
def get_extended_resources(self, version):
"""Retrieve extended resources or attributes for core resources.
Extended attributes are implemented by a core plugin similarly
to the attributes defined in the core, and can appear in
request and response messages. Their names are scoped with the
extension's prefix. The core API version is passed to this
function, which must return a
map[<resource_name>][<attribute_name>][<attribute_property>]
specifying the extended resource attribute properties required
by that API version.
Extension can add resources and their attr definitions too.
The returned map can be integrated into RESOURCE_ATTRIBUTE_MAP.
"""
return {}
def get_plugin_interface(self):
"""Returns an abstract class which defines contract for the plugin.
The abstract class should inherit from
neutron_lib.services.base.ServicePluginBase.
Methods in this abstract class should be decorated as abstractmethod
"""
def get_required_extensions(self):
"""Return list of extensions required for processing this descriptor.
Without these extensions present in a neutron deployment, the
introduced extension cannot load or function properly.
"""
return []
def get_optional_extensions(self):
"""Returns a list of optionally required extensions.
Unlike get_required_extensions. This will not fail the loading of
the extension if one of these extensions is not present. This is
useful for an extension that extends multiple resources across
other extensions that should still work for the remaining extensions
when one is missing.
"""
return []
def update_attributes_map(self, extended_attributes,
extension_attrs_map=None):
"""Update attributes map for this extension.
This is default method for extending an extension's attributes map.
An extension can use this method and supplying its own resource
attribute map in extension_attrs_map argument to extend all its
attributes that needs to be extended.
If an extension does not implement update_attributes_map, the method
does nothing and just return.
"""
if not extension_attrs_map:
return
for resource, attrs in extension_attrs_map.items():
extended_attrs = extended_attributes.get(resource)
if extended_attrs:
attrs.update(extended_attrs)
def get_pecan_resources(self):
"""List of PecanResourceExtension extension objects.
Resources define new nouns, and are accessible through URLs.
The controllers associated with each instance of
extensions.ResourceExtension should be a subclass of
neutron.pecan_wsgi.controllers.utils.NeutronPecanController.
If a resource is defined in both get_resources and get_pecan_resources,
the resource defined in get_pecan_resources will take precedence.
"""
return []
class APIExtensionDescriptor(ExtensionDescriptor):
"""Base class that defines the contract for extensions.
Concrete implementations of API extensions should first provide
an API definition in neutron_lib.api.definitions. The API
definition module (object reference) can then be specified as a
class level attribute on the concrete extension.
For example::
from neutron_lib.api.definitions import provider_net
from neutron_lib.api import extensions
class Providernet(extensions.APIExtensionDescriptor):
api_definition = provider_net
# nothing else needed if default behavior is acceptable
If extension implementations need to override the default behavior of
this class they can override the respective method directly.
"""
api_definition = _UNSET
@classmethod
def _assert_api_definition(cls, attr=None):
if cls.api_definition == _UNSET:
raise NotImplementedError(
_("Extension module API definition not set."))
if attr and getattr(cls.api_definition, attr, _UNSET) == _UNSET:
raise NotImplementedError(_("Extension module API definition "
"does not define '%s'") % attr)
@classmethod
def get_name(cls):
"""The name of the API definition."""
cls._assert_api_definition('NAME')
return cls.api_definition.NAME
@classmethod
def get_alias(cls):
"""The alias for the API definition."""
cls._assert_api_definition('ALIAS')
return cls.api_definition.ALIAS
@classmethod
def get_description(cls):
"""Friendly description for the API definition."""
cls._assert_api_definition('DESCRIPTION')
return cls.api_definition.DESCRIPTION
@classmethod
def get_updated(cls):
"""The timestamp when the API definition was last updated."""
cls._assert_api_definition('UPDATED_TIMESTAMP')
return cls.api_definition.UPDATED_TIMESTAMP
@classmethod
def get_extended_resources(cls, version):
"""Retrieve the extended resource map for the API definition.
:param version: The API version to retrieve the resource attribute
map for.
:returns: The extended resource map for the underlying API definition
if the version is 2.0. The extended resource map returned includes
both the API definition's RESOURCE_ATTRIBUTE_MAP and
SUB_RESOURCE_ATTRIBUTE_MAP where applicable. If the version is
not 2.0, an empty dict is returned.
"""
if version == "2.0":
cls._assert_api_definition('RESOURCE_ATTRIBUTE_MAP')
cls._assert_api_definition('SUB_RESOURCE_ATTRIBUTE_MAP')
# support api defs that use None for sub attr map
sub_attrs = cls.api_definition.SUB_RESOURCE_ATTRIBUTE_MAP or {}
return dict(
list(cls.api_definition.RESOURCE_ATTRIBUTE_MAP.items()) +
list(sub_attrs.items()))
else:
return {}
@classmethod
def get_required_extensions(cls):
"""Returns the API definition's required extensions."""
cls._assert_api_definition('REQUIRED_EXTENSIONS')
return cls.api_definition.REQUIRED_EXTENSIONS
@classmethod
def get_optional_extensions(cls):
"""Returns the API definition's optional extensions."""
cls._assert_api_definition('OPTIONAL_EXTENSIONS')
return cls.api_definition.OPTIONAL_EXTENSIONS
@classmethod
def update_attributes_map(cls, attributes, extension_attrs_map=None):
"""Update attributes map for this extension.
Behaves like ExtensionDescriptor.update_attributes_map(), but
if extension_attrs_map is not given the dict returned from
self.get_extended_resources('2.0') is used.
"""
if extension_attrs_map is None:
extension_attrs_map = cls.get_extended_resources('2.0')
super(APIExtensionDescriptor, cls()).update_attributes_map(
attributes, extension_attrs_map=extension_attrs_map)