171 lines
4.8 KiB
Python
171 lines
4.8 KiB
Python
# Copyright (c) 2013 Mirantis Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import abc
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import inspect
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from oslo.config import cfg
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from savanna import config
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from savanna.openstack.common import importutils
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from savanna.openstack.common import log as logging
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from savanna.utils import resources
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LOG = logging.getLogger(__name__)
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opts = [
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cfg.ListOpt('plugins',
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default=[],
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help='List of plugins to be loaded'),
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]
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CONF = cfg.CONF
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CONF.register_opts(opts)
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class PluginInterface(resources.BaseResource):
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__metaclass__ = abc.ABCMeta
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__resource_name__ = 'plugin'
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name = 'plugin_interface'
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def get_plugin_opts(self):
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"""Plugin can expose some options that should be specified in conf file
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For example:
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def get_plugin_opts(self):
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return [
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cfg.StrOpt('mandatory-conf', required=True),
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cfg.StrOpt('optional_conf', default="42"),
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]
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"""
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return []
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def setup(self, conf):
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"""Plugin initialization
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:param conf: plugin-specific configurations
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"""
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pass
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@abc.abstractmethod
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def get_title(self):
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"""Plugin title
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For example:
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"Vanilla Provisioning"
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"""
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pass
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def get_description(self):
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"""Optional description of the plugin
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This information is targeted to be displayed in UI.
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"""
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pass
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def to_dict(self):
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return {
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'name': self.name,
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'title': self.get_title(),
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'description': self.get_description(),
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}
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class PluginManager(object):
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def __init__(self):
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self.plugins = {}
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self._load_all_plugins()
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def _load_all_plugins(self):
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LOG.debug("List of requested plugins: %s" % CONF.plugins)
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if len(CONF.plugins) > len(set(CONF.plugins)):
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raise RuntimeError("plugins config contains non-unique entries")
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# register required 'plugin_factory' property for each plugin
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for plugin in CONF.plugins:
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opts = [
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cfg.StrOpt('plugin_class', required=True),
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]
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CONF.register_opts(opts, group='plugin:%s' % plugin)
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config.parse_configs()
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# register plugin-specific configs
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for plugin_name in CONF.plugins:
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self.plugins[plugin_name] = self._get_plugin_instance(plugin_name)
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config.parse_configs()
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titles = []
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for plugin_name in CONF.plugins:
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plugin = self.plugins[plugin_name]
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plugin.setup(CONF['plugin:%s' % plugin_name])
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title = plugin.get_title()
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if title in titles:
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# replace with specific error
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raise RuntimeError(
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"Title of plugin '%s' isn't unique" % plugin_name)
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titles.append(title)
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LOG.info("Plugin '%s' defined and loaded" % plugin_name)
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def _get_plugin_instance(self, plugin_name):
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plugin_path = CONF['plugin:%s' % plugin_name].plugin_class
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module_path, klass = [s.strip() for s in plugin_path.split(':')]
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if not module_path or not klass:
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# TODO(slukjanov): replace with specific error
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raise RuntimeError("Incorrect plugin_class: '%s'" %
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plugin_path)
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module = importutils.try_import(module_path)
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if not hasattr(module, klass):
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# TODO(slukjanov): replace with specific error
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raise RuntimeError("Class not found: '%s'" % plugin_path)
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plugin_class = getattr(module, klass)
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if not inspect.isclass(plugin_class):
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# TODO(slukjanov): replace with specific error
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raise RuntimeError("'%s' isn't a class" % plugin_path)
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plugin = plugin_class()
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plugin.name = plugin_name
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CONF.register_opts(plugin.get_plugin_opts(),
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group='plugin:%s' % plugin_name)
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return plugin
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def get_plugins(self, base):
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return [
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self.plugins[plugin] for plugin in self.plugins
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if not base or issubclass(self.plugins[plugin].__class__, base)
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]
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def get_plugin(self, plugin_name):
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return self.plugins.get(plugin_name)
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PLUGINS = None
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def setup_plugins():
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global PLUGINS
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PLUGINS = PluginManager()
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