5834af13d7
This updates oslo.config to be in-line with global-requirements, and renames all the old references of 'oslo.config' to the newer oslo_config. Change-Id: I68d8f67d37bca918ce1193c2a19e00f7ed4f6caa
68 lines
2.2 KiB
Python
68 lines
2.2 KiB
Python
# Copyright (c) 2014 Hewlett-Packard Development Company, L.P.
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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. 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 six
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from oslo_config import cfg
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from stevedore.enabled import EnabledExtensionManager
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CONF = cfg.CONF
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def is_enabled(ext):
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"""Check to see whether a plugin should be enabled. Assumes that the
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plugin extends PluginBase.
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:param ext: The extension instance to check.
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:return: True if it should be enabled. Otherwise false.
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"""
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return ext.obj.enabled()
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@six.add_metaclass(abc.ABCMeta)
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class PluginBase(object):
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"""Base class for all storyboard plugins.
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Every storyboard plugin will be provided an instance of the application
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configuration, and will then be asked whether it should be enabled. Each
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plugin should decide, given the configuration and the environment,
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whether it has the necessary resources to operate properly.
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"""
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def __init__(self, config):
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self.config = config
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@abc.abstractmethod
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def enabled(self):
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"""A method which indicates whether this plugin is properly
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configured and should be enabled. If it's ready to go, return True.
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Otherwise, return False.
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"""
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class StoryboardPluginLoader(EnabledExtensionManager):
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"""The storyboard plugin loader, a stevedore abstraction that formalizes
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our plugin contract.
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"""
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def __init__(self, namespace, on_load_failure_callback=None):
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super(StoryboardPluginLoader, self) \
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.__init__(namespace=namespace,
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check_func=is_enabled,
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invoke_on_load=True,
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invoke_args=(CONF,),
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on_load_failure_callback=on_load_failure_callback)
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