149 lines
4.7 KiB
Python
149 lines
4.7 KiB
Python
# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import abc
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import six
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import stevedore
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from keystoneauth1 import exceptions
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PLUGIN_NAMESPACE = 'keystoneauth1.plugin'
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__all__ = ('get_available_plugin_names',
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'get_available_plugin_loaders',
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'get_plugin_loader',
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'get_plugin_options',
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'BaseLoader',
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'PLUGIN_NAMESPACE')
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def get_available_plugin_names():
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"""Get the names of all the plugins that are available on the system.
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This is particularly useful for help and error text to prompt a user for
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example what plugins they may specify.
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:returns: A list of names.
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:rtype: frozenset
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"""
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mgr = stevedore.ExtensionManager(namespace=PLUGIN_NAMESPACE)
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return frozenset(mgr.names())
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def get_available_plugin_loaders():
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"""Retrieve all the plugin classes available on the system.
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:returns: A dict with plugin entrypoint name as the key and the plugin
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loader as the value.
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:rtype: dict
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"""
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mgr = stevedore.ExtensionManager(namespace=PLUGIN_NAMESPACE,
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invoke_on_load=True,
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propagate_map_exceptions=True)
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return dict(mgr.map(lambda ext: (ext.entry_point.name, ext.obj)))
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def get_plugin_loader(name):
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"""Retrieve a plugin class by its entrypoint name.
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:param str name: The name of the object to get.
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:returns: An auth plugin class.
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:rtype: :py:class:`keystoneauth1.loading.BaseLoader`
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:raises keystoneauth1.exceptions.auth_plugins.NoMatchingPlugin:
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if a plugin cannot be created.
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"""
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try:
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mgr = stevedore.DriverManager(namespace=PLUGIN_NAMESPACE,
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invoke_on_load=True,
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name=name)
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except RuntimeError:
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raise exceptions.NoMatchingPlugin(name)
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return mgr.driver
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def get_plugin_options(name):
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"""Get the options for a specific plugin.
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This will be the list of options that is registered and loaded by the
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specified plugin.
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:returns: A list of :py:class:`keystoneauth1.loading.Opt` options.
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:raises keystoneauth1.exceptions.auth_plugins.NoMatchingPlugin:
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if a plugin cannot be created.
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"""
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return get_plugin_loader(name).get_options()
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@six.add_metaclass(abc.ABCMeta)
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class BaseLoader(object):
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@abc.abstractproperty
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def plugin_class(self):
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raise NotImplemented()
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@abc.abstractmethod
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def get_options(self):
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"""Return the list of parameters associated with the auth plugin.
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This list may be used to generate CLI or config arguments.
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:returns: A list of Param objects describing available plugin
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parameters.
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:rtype: list
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"""
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return []
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def load_from_options(self, **kwargs):
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"""Create a plugin from the arguments retrieved from get_options.
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A client can override this function to do argument validation or to
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handle differences between the registered options and what is required
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to create the plugin.
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"""
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missing_required = [o for o in self.get_options()
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if o.required and kwargs.get(o.dest) is None]
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if missing_required:
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raise exceptions.MissingRequiredOptions(missing_required)
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return self.plugin_class(**kwargs)
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def load_from_options_getter(self, getter, **kwargs):
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"""Load a plugin from getter function that returns appropriate values.
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To handle cases other than the provided CONF and CLI loading you can
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specify a custom loader function that will be queried for the option
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value.
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The getter is a function that takes a
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:py:class:`keystoneauth1.loading.Opt` and returns a value to load with.
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:param getter: A function that returns a value for the given opt.
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:type getter: callable
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:returns: An authentication Plugin.
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:rtype: :py:class:`keystoneauth1.plugin.BaseAuthPlugin`
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"""
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for opt in (o for o in self.get_options() if o.dest not in kwargs):
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val = getter(opt)
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if val is not None:
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val = opt.type(val)
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kwargs[opt.dest] = val
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return self.load_from_options(**kwargs)
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