d8e0dc21e0
Add support to oslo.db to be used as a DB driver. The DB driver will be
used with API v2. When it's completely implemented, API V1 will be
deprecated and removed by the end of the cycle. Freezer-api will keep
supporting V2 with Elasticsearch, Sqlalchemy drivers.
This patch implements the follow:
* Abstract Base DB driver to be implemented by each driver
* Base driver; will return only access to the db engine, session
* SqlAlchemy driver;
* ElasticSearch driver;
* Implement both drivers in freezer-manage
Partially-Implements: blueprint oslo-db
Depends-On: I81e417155da48f46dd2113e5745fb3c21c96499f
Depends-On: I2e5724b1f1a75121952e2beb3844d2c489e4df68
Depends-On: Idb4ac050652d1d0107bf3fcd447d7cbedd811809
Depends-On: I81d46c89859752c0cbc21ef02de90db7f19f942c
Change-Id: I93ed1b909f538728a1a9bd5c8b07baf7aeddb705
66 lines
2.2 KiB
Python
66 lines
2.2 KiB
Python
"""
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(c) Copyright 2014,2015 Hewlett-Packard Development Company, L.P.
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(C) Copyright 2016-2018 Hewlett Packard Enterprise Development Company LP
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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"""
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import sys
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from oslo_log import log
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from oslo_utils import importutils
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from stevedore import driver
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LOG = log.getLogger(__name__)
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_DB_DRIVER_NAMESPACE = "freezer.db.backends"
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def _load_class_by_alias_or_classname(namespace, name):
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"""Load class using stevedore alias or the class name
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:param namespace: namespace where the alias is defined
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:param name: alias or class name of the class to be loaded
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:returns: class if calls can be loaded
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:raises ImportError if class cannot be loaded
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"""
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if not name:
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LOG.error("Alias or class name is not set")
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raise ImportError("Class not found.")
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try:
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# Try to resolve class by alias
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mgr = driver.DriverManager(
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namespace, name, warn_on_missing_entrypoint=False)
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class_to_load = mgr.driver
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except RuntimeError:
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e1_info = sys.exc_info()
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# Fallback to class name
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try:
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class_to_load = importutils.import_class(name)
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except (ImportError, ValueError):
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LOG.error("Error loading class by alias",
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exc_info=e1_info)
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LOG.error("Error loading class by class name",
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exc_info=True)
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raise ImportError("Class not found.")
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return class_to_load
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def get_db_driver(name, backend):
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"""
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Loads database driver
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:param name: name of the database driver.
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:return: Instance of the driver class
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"""
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driver_class = _load_class_by_alias_or_classname(_DB_DRIVER_NAMESPACE,
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name)
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return driver_class(backend=backend)
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