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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2011 Nicira Networks, Inc
# 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
# 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.
# @author: Somik Behera, Nicira Networks, Inc.
Quantum's Manager class is responsible for parsing a config file and
instantiating the correct plugin that concretely implement quantum_plugin_base
The caller should make sure that QuantumManager is a singleton.
import gettext
import logging
import os
gettext.install('quantum', unicode=1)
from quantum.common import utils
from quantum.common.config import find_config_file
from quantum.common.exceptions import ClassNotFound
from quantum_plugin_base import QuantumPluginBase
LOG = logging.getLogger('quantum.manager')
CONFIG_FILE = "plugins.ini"
LOG = logging.getLogger('quantum.manager')
def find_config(basepath):
for root, dirs, files in os.walk(basepath):
if CONFIG_FILE in files:
return os.path.join(root, CONFIG_FILE)
return None
class QuantumManager(object):
_instance = None
def __init__(self, options=None, config_file=None):
# If no options have been provided, create an empty dict
if not options:
options = {}
if config_file:
config_file = [config_file]
self.configuration_file = find_config_file(options, config_file,
if not 'plugin_provider' in options:
options['plugin_provider'] = \
LOG.debug("Plugin location:%s", options['plugin_provider'])
# If the plugin can't be found let them know gracefully
plugin_klass = utils.import_class(options['plugin_provider'])
except ClassNotFound:
raise Exception("Plugin not found. You can install a " \
"plugin with: pip install <plugin-name>\n" \
"Example: pip install quantum-sample-plugin")
if not issubclass(plugin_klass, QuantumPluginBase):
raise Exception("Configured Quantum plug-in " \
"didn't pass compatibility test")
LOG.debug("Successfully imported Quantum plug-in." \
"All compatibility tests passed")
self.plugin = plugin_klass()
def get_plugin(cls, options=None, config_file=None):
if cls._instance is None:
cls._instance = cls(options, config_file)
return cls._instance.plugin