Add the plugin framework from common; use and test.
For blueprint novaplugins. Change-Id: Id4a5ae3ebb91f941956e2f73ecfd9ea1d290a235
This commit is contained in:
Andrew Bogott
parent
500ee77121
commit
a30ed72967
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@ -18,6 +18,7 @@
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from nova.api.openstack import extensions as base_extensions
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from nova import flags
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from nova.openstack.common import log as logging
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from nova.openstack.common.plugin import pluginmanager
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LOG = logging.getLogger(__name__)
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@ -29,5 +30,9 @@ class ExtensionManager(base_extensions.ExtensionManager):
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LOG.audit(_('Initializing extension manager.'))
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self.cls_list = FLAGS.osapi_compute_extension
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self.PluginManager = pluginmanager.PluginManager('nova',
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'compute-extensions')
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self.PluginManager.load_plugins()
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self.cls_list.append(self.PluginManager.plugin_extension_factory)
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self.extensions = {}
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self._load_extensions()
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@ -246,8 +246,11 @@ class ExtensionManager(object):
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LOG.debug(_("Loading extension %s"), ext_factory)
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# Load the factory
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factory = importutils.import_class(ext_factory)
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if isinstance(ext_factory, basestring):
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# Load the factory
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factory = importutils.import_class(ext_factory)
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else:
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factory = ext_factory
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# Call it
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LOG.debug(_("Calling extension factory %s"), ext_factory)
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@ -30,4 +30,5 @@ class ExtensionManager(base_extensions.ExtensionManager):
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self.cls_list = FLAGS.osapi_volume_extension
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self.extensions = {}
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self.plugins = []
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self._load_extensions()
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@ -56,6 +56,7 @@ This module provides Manager, a base class for managers.
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from nova.db import base
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from nova import flags
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from nova.openstack.common import log as logging
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from nova.openstack.common.plugin import pluginmanager
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from nova.openstack.common.rpc import dispatcher as rpc_dispatcher
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from nova.scheduler import rpcapi as scheduler_rpcapi
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from nova import version
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@ -138,8 +139,13 @@ class Manager(base.Base):
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if not host:
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host = FLAGS.host
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self.host = host
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self.load_plugins()
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super(Manager, self).__init__(db_driver)
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def load_plugins(self):
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pluginmgr = pluginmanager.PluginManager('nova', self.__class__)
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pluginmgr.load_plugins()
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def create_rpc_dispatcher(self):
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'''Get the rpc dispatcher for this manager.
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@ -205,6 +211,10 @@ class SchedulerDependentManager(Manager):
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self.scheduler_rpcapi = scheduler_rpcapi.SchedulerAPI()
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super(SchedulerDependentManager, self).__init__(host, db_driver)
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def load_plugins(self):
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pluginmgr = pluginmanager.PluginManager('nova', self.service_name)
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pluginmgr.load_plugins()
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def update_service_capabilities(self, capabilities):
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"""Remember these capabilities to send on next periodic update."""
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self.last_capabilities = capabilities
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@ -0,0 +1,14 @@
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# Copyright 2012 OpenStack LLC.
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# All Rights Reserved.
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#
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# 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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@ -0,0 +1,93 @@
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# Copyright 2012 OpenStack LLC.
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# All Rights Reserved.
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#
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# 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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from nova.openstack.common import log as logging
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from nova.openstack.common.plugin import plugin
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LOG = logging.getLogger(__name__)
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class _CallbackNotifier(object):
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"""Manages plugin-defined notification callbacks.
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For each Plugin, a CallbackNotifier will be added to the
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notification driver list. Calls to notify() with appropriate
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messages will be hooked and prompt callbacks.
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A callback should look like this:
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def callback(context, message, user_data)
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"""
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def __init__(self):
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self._callback_dict = {}
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def _add_callback(self, event_type, callback, user_data):
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callback_list = self._callback_dict.get(event_type, [])
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callback_list.append({'function': callback,
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'user_data': user_data})
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self._callback_dict[event_type] = callback_list
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def _remove_callback(self, callback):
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for callback_list in self._callback_dict.values():
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for entry in callback_list:
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if entry['function'] == callback:
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callback_list.remove(entry)
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def notify(self, context, message):
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if message.get('event_type') not in self._callback_dict:
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return
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for entry in self._callback_dict[message.get('event_type')]:
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entry['function'](context, message, entry.get('user_data'))
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def callbacks(self):
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return self._callback_dict
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class CallbackPlugin(plugin.Plugin):
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""" Plugin with a simple callback interface.
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This class is provided as a convenience for producing a simple
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plugin that only watches a couple of events. For example, here's
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a subclass which prints a line the first time an instance is created.
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class HookInstanceCreation(CallbackPlugin):
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def __init__(self, _service_name):
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super(HookInstanceCreation, self).__init__()
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self._add_callback(self.magic, 'compute.instance.create.start')
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def magic(self):
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print "An instance was created!"
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self._remove_callback(self, self.magic)
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"""
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def __init__(self, service_name):
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super(CallbackPlugin, self).__init__(service_name)
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self._callback_notifier = _CallbackNotifier()
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self._add_notifier(self._callback_notifier)
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def _add_callback(self, callback, event_type, user_data=None):
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"""Add callback for a given event notification.
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Subclasses can call this as an alternative to implementing
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a fullblown notify notifier.
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"""
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self._callback_notifier._add_callback(event_type, callback, user_data)
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def _remove_callback(self, callback):
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"""Remove all notification callbacks to specified function."""
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self._callback_notifier._remove_callback(callback)
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@ -0,0 +1,87 @@
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# Copyright 2012 OpenStack LLC.
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# All Rights Reserved.
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#
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# 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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from nova.openstack.common import log as logging
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from nova.openstack.common.notifier import list_notifier
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LOG = logging.getLogger(__name__)
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class Plugin(object):
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"""Defines an interface for adding functionality to an OpenStack service.
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A plugin interacts with a service via the following pathways:
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- An optional set of notifiers, managed by calling add_notifier()
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or by overriding _notifiers()
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- A set of api extensions, managed via add_api_extension_descriptor()
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- Direct calls to service functions.
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- Whatever else the plugin wants to do on its own.
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This is the reference implementation.
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"""
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# The following functions are provided as convenience methods
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# for subclasses. Subclasses should call them but probably not
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# override them.
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def _add_api_extension_descriptor(self, descriptor):
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"""Subclass convenience method which adds an extension descriptor.
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Subclass constructors should call this method when
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extending a project's REST interface.
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Note that once the api service has loaded, the
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API extension set is more-or-less fixed, so
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this should mainly be called by subclass constructors.
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"""
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self._api_extension_descriptors.append(descriptor)
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def _add_notifier(self, notifier):
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"""Subclass convenience method which adds a notifier.
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Notifier objects should implement the function notify(message).
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Each notifier receives a notify() call whenever an openstack
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service broadcasts a notification.
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Best to call this during construction. Notifiers are enumerated
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and registered by the pluginmanager at plugin load time.
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"""
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self._notifiers.append(notifier)
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# The following methods are called by OpenStack services to query
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# plugin features. Subclasses should probably not override these.
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def _notifiers(self):
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"""Returns list of notifiers for this plugin."""
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return self._notifiers
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notifiers = property(_notifiers)
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def _api_extension_descriptors(self):
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"""Return a list of API extension descriptors.
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Called by a project API during its load sequence.
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"""
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return self._api_extension_descriptors
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api_extension_descriptors = property(_api_extension_descriptors)
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# Most plugins will override this:
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def __init__(self, service_name):
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self._notifiers = []
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self._api_extension_descriptors = []
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@ -0,0 +1,95 @@
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# Copyright 2012 OpenStack LLC.
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# All Rights Reserved.
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#
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# 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 imp
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import os
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import pkg_resources
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from nova.openstack.common import cfg
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from nova.openstack.common import log as logging
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from nova.openstack.common.notifier import list_notifier
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CONF = cfg.CONF
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LOG = logging.getLogger(__name__)
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class PluginManager(object):
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"""Manages plugin entrypoints and loading.
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For a service to implement this plugin interface for callback purposes:
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- Make use of the openstack-common notifier system
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- Instantiate this manager in each process (passing in
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project and service name)
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For an API service to extend itself using this plugin interface,
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it needs to query the plugin_extension_factory provided by
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the already-instantiated PluginManager.
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"""
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def __init__(self, project_name, service_name):
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""" Construct Plugin Manager; load and initialize plugins.
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project_name (e.g. 'nova' or 'glance') is used
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to construct the entry point that identifies plugins.
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The service_name (e.g. 'compute') is passed on to
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each plugin as a raw string for it to do what it will.
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"""
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self._project_name = project_name
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self._service_name = service_name
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self.plugins = []
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def _force_use_list_notifier(self):
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if (CONF.notification_driver !=
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'nova.openstack.common.notifier.list_notifier'):
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if not hasattr(CONF, "list_notifier_drivers"):
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CONF.list_notifier_drivers = []
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old_notifier = CONF.notification_driver
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drvstring = 'nova.openstack.common.notifier.list_notifier'
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CONF.notification_driver = drvstring
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if old_notifier:
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list_notifier.add_driver(old_notifier)
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def load_plugins(self):
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self.plugins = []
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for entrypoint in pkg_resources.iter_entry_points('%s.plugin' %
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self._project_name):
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try:
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pluginclass = entrypoint.load()
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plugin = pluginclass(self._service_name)
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self.plugins.append(plugin)
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except Exception, exc:
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LOG.error(_("Failed to load plugin %(plug)s: %(exc)s") %
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{'plug': entrypoint, 'exc': exc})
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# See if we need to turn on the list notifier
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for plugin in self.plugins:
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if plugin.notifiers:
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self._force_use_list_notifier()
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break
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# Register individual notifiers.
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for plugin in self.plugins:
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for notifier in plugin.notifiers:
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list_notifier.add_driver(notifier)
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def plugin_extension_factory(self, ext_mgr):
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for plugin in self.plugins:
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descriptors = plugin.api_extension_descriptors
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for descriptor in descriptors:
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ext_mgr.load_extension(descriptor)
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@ -0,0 +1,90 @@
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# Copyright 2011 OpenStack LLC.
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# All Rights Reserved.
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#
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# 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 pkg_resources
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import nova
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from nova.api.openstack.compute import extensions as computeextensions
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from nova.api.openstack import extensions
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from nova.openstack.common.plugin import plugin
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from nova.openstack.common.plugin import pluginmanager
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from nova import test
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class StubController(object):
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def i_am_the_stub(self):
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pass
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class StubControllerExtension(extensions.ExtensionDescriptor):
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"""This is a docstring. We need it."""
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name = 'stubextension'
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alias = 'stubby'
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def get_resources(self):
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resources = []
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res = extensions.ResourceExtension('testme',
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StubController())
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resources.append(res)
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return resources
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service_list = []
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class TestPluginClass(plugin.Plugin):
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def __init__(self, service_name):
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super(TestPluginClass, self).__init__(service_name)
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self._add_api_extension_descriptor(StubControllerExtension)
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service_list.append(service_name)
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class MockEntrypoint(pkg_resources.EntryPoint):
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def load(self):
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return TestPluginClass
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class APITestCase(test.TestCase):
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"""Test case for the plugin api extension interface"""
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def test_add_extension(self):
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def mock_load(_s):
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return TestPluginClass()
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def mock_iter_entry_points(_t):
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return [MockEntrypoint("fake", "fake", ["fake"])]
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self.stubs.Set(pkg_resources, 'iter_entry_points',
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mock_iter_entry_points)
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global service_list
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service_list = []
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# Marking out the default extension paths makes this test MUCH faster.
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self.flags(osapi_compute_extension=[])
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self.flags(osapi_volume_extension=[])
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found = False
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mgr = computeextensions.ExtensionManager()
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for res in mgr.get_resources():
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# We have to use this weird 'dir' check because
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# the plugin framework muddies up the classname
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# such that 'isinstance' doesn't work right.
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if 'i_am_the_stub' in dir(res.controller):
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found = True
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self.assertTrue(found)
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self.assertEqual(len(service_list), 1)
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self.assertEqual(service_list[0], 'compute-extensions')
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@ -1,7 +1,7 @@
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[DEFAULT]
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# The list of modules to copy from openstack-common
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modules=cfg,context,excutils,gettextutils,importutils,iniparser,jsonutils,local,log,notifier,policy,setup,timeutils,rpc
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modules=cfg,context,excutils,gettextutils,importutils,iniparser,jsonutils,local,log,notifier,plugin,policy,setup,timeutils,rpc
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# The base module to hold the copy of openstack.common
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base=nova
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