5fc7ee5f62
Provides a place for any drivers to potentially
setup graceful-shutdown code.
VMware driver's proper driver-lifecycle code included.
This is critical in environments where the the vmware
driver is setup and torn down at high frequency.
Prevents run-away vSphere by closing stateless
HTTP management sessions gracefully.
Change-Id: I67a91613643540243ab1210b333ed8e121f05802
related to bug: 1262288
Closes-bug: 1292583
117 lines
4.2 KiB
Python
117 lines
4.2 KiB
Python
# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# 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, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Base Manager class.
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Managers are responsible for a certain aspect of the system. It is a logical
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grouping of code relating to a portion of the system. In general other
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components should be using the manager to make changes to the components that
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it is responsible for.
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For example, other components that need to deal with volumes in some way,
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should do so by calling methods on the VolumeManager instead of directly
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changing fields in the database. This allows us to keep all of the code
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relating to volumes in the same place.
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We have adopted a basic strategy of Smart managers and dumb data, which means
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rather than attaching methods to data objects, components should call manager
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methods that act on the data.
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Methods on managers that can be executed locally should be called directly. If
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a particular method must execute on a remote host, this should be done via rpc
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to the service that wraps the manager
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Managers should be responsible for most of the db access, and
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non-implementation specific data. Anything implementation specific that can't
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be generalized should be done by the Driver.
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In general, we prefer to have one manager with multiple drivers for different
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implementations, but sometimes it makes sense to have multiple managers. You
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can think of it this way: Abstract different overall strategies at the manager
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level(FlatNetwork vs VlanNetwork), and different implementations at the driver
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level(LinuxNetDriver vs CiscoNetDriver).
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Managers will often provide methods for initial setup of a host or periodic
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tasks to a wrapping service.
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This module provides Manager, a base class for managers.
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"""
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from oslo.config import cfg
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from nova.db import base
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from nova.openstack.common import log as logging
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from nova.openstack.common import periodic_task
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from nova import rpc
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CONF = cfg.CONF
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CONF.import_opt('host', 'nova.netconf')
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LOG = logging.getLogger(__name__)
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class Manager(base.Base, periodic_task.PeriodicTasks):
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def __init__(self, host=None, db_driver=None, service_name='undefined'):
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if not host:
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host = CONF.host
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self.host = host
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self.backdoor_port = None
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self.service_name = service_name
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self.notifier = rpc.get_notifier(self.service_name, self.host)
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self.additional_endpoints = []
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super(Manager, self).__init__(db_driver)
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def periodic_tasks(self, context, raise_on_error=False):
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"""Tasks to be run at a periodic interval."""
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return self.run_periodic_tasks(context, raise_on_error=raise_on_error)
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def init_host(self):
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"""Hook to do additional manager initialization when one requests
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the service be started. This is called before any service record
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is created.
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Child classes should override this method.
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"""
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pass
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def cleanup_host(self):
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"""Hook to do cleanup work when the service shuts down.
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Child classes should override this method.
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"""
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pass
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def pre_start_hook(self):
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"""Hook to provide the manager the ability to do additional
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start-up work before any RPC queues/consumers are created. This is
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called after other initialization has succeeded and a service
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record is created.
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Child classes should override this method.
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"""
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pass
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def post_start_hook(self):
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"""Hook to provide the manager the ability to do additional
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start-up work immediately after a service creates RPC consumers
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and starts 'running'.
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Child classes should override this method.
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"""
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pass
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