74 lines
2.4 KiB
Python
74 lines
2.4 KiB
Python
# (c) Copyright 2016 Hewlett-Packard Development Enterprise, 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 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 os
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from oslo_config import cfg
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from oslo_log import log
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from oslo_utils import importutils
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from freezer.exceptions import engine as engine_exceptions
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CONF = cfg.CONF
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LOG = log.getLogger(__name__)
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class EngineManager(object):
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"""
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EngineManager, this class handles engines.
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Lists all available engines
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Checks if an engine does exists or not
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Load an engine
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"""
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def __init__(self):
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"""
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This function does some initialization for the engine manager and
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register some variables from the CONF variable into the local class
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"""
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self.engine_name = CONF.engine_name
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self.engine_store = os.path.abspath(os.path.dirname(__file__))
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self.engines = self.list_engines()
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def load_engine(self, **kwargs):
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""" Check if the engine exists or not. If not raise EngineNotFound
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Error. If the engine exists then try to get an instance of this engine.
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"""
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if not self._check_engine_exists():
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raise engine_exceptions.EngineNotFound(
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"Engine {0} not found".format(self.engine_name)
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)
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return importutils.import_object(
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"freezer.engine.{0}.{0}.{1}Engine".format(
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self.engine_name,
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self.engine_name.capitalize()
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),
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**kwargs
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)
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def _check_engine_exists(self):
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if self.engine_name not in self.engines:
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return False
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return True
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def list_engines(self):
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"""
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Lists all engines in the engine directory
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:return:
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"""
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engines = [
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name for name in os.listdir(self.engine_store) if
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os.path.isdir(os.path.join(self.engine_store, name))
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]
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return engines
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