neutron/neutron/service.py
Armando Migliaccio 17563a802e Adopt neutron-lib plugin directory
Neutron Manager is loaded at the very startup of the neutron
server process and with it plugins are loaded and stored for
lookup purposes as their references are widely used across the
entire neutron codebase.

Rather than holding these references directly in NeutronManager
this patch refactors the code so that these references are held
by a plugin directory.

This allows subprojects and other parts of the Neutron codebase
to use the directory in lieu of the manager. The result is a
leaner, cleaner, and more decoupled code.

Usage pattern [1,2] can be translated to [3,4] respectively.

[1] manager.NeutronManager.get_service_plugins()[FOO]
[2] manager.NeutronManager.get_plugin()
[3] directory.get_plugin(FOO)
[4] directory.get_plugin()

The more entangled part is in the neutron unit tests, where the
use of the manager can be simplified as mocking is typically
replaced by a call to the directory add_plugin() method. This is
safe as each test case gets its own copy of the plugin directory.
That said, unit tests that look more like API tests and that rely on
the entire plugin machinery, need some tweaking to avoid stumbling
into plugin loading failures.

Due to the massive use of the manager, deprecation warnings are
considered impractical as they cause logs to bloat out of proportion.

Follow-up patches that show how to adopt the directory in neutron
subprojects are tagged with topic:plugin-directory.

NeutronLibImpact

Partially-implements: blueprint neutron-lib

Change-Id: I7331e914234c5f0b7abe836604fdd7e4067551cf
2016-11-23 04:45:33 -07:00

423 lines
14 KiB
Python

# Copyright 2011 VMware, Inc
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import inspect
import os
import random
from neutron_lib.plugins import directory
from oslo_concurrency import processutils
from oslo_config import cfg
from oslo_log import log as logging
from oslo_messaging import server as rpc_server
from oslo_service import loopingcall
from oslo_service import service as common_service
from oslo_utils import excutils
from oslo_utils import importutils
from neutron._i18n import _LE, _LI
from neutron.callbacks import events
from neutron.callbacks import registry
from neutron.callbacks import resources
from neutron.common import config
from neutron.common import profiler
from neutron.common import rpc as n_rpc
from neutron.conf import service
from neutron import context
from neutron.db import api as session
from neutron import worker as neutron_worker
from neutron import wsgi
service.register_service_opts(service.service_opts)
LOG = logging.getLogger(__name__)
class WsgiService(object):
"""Base class for WSGI based services.
For each api you define, you must also define these flags:
:<api>_listen: The address on which to listen
:<api>_listen_port: The port on which to listen
"""
def __init__(self, app_name):
self.app_name = app_name
self.wsgi_app = None
def start(self):
self.wsgi_app = _run_wsgi(self.app_name)
def wait(self):
self.wsgi_app.wait()
class NeutronApiService(WsgiService):
"""Class for neutron-api service."""
def __init__(self, app_name):
profiler.setup('neutron-server', cfg.CONF.host)
super(NeutronApiService, self).__init__(app_name)
@classmethod
def create(cls, app_name='neutron'):
# Setup logging early
config.setup_logging()
service = cls(app_name)
return service
def serve_wsgi(cls):
try:
service = cls.create()
service.start()
except Exception:
with excutils.save_and_reraise_exception():
LOG.exception(_LE('Unrecoverable error: please check log '
'for details.'))
registry.notify(resources.PROCESS, events.BEFORE_SPAWN, service)
return service
class RpcWorker(neutron_worker.NeutronWorker):
"""Wraps a worker to be handled by ProcessLauncher"""
start_listeners_method = 'start_rpc_listeners'
def __init__(self, plugins, worker_process_count=1):
super(RpcWorker, self).__init__(
worker_process_count=worker_process_count
)
self._plugins = plugins
self._servers = []
def start(self):
super(RpcWorker, self).start()
for plugin in self._plugins:
if hasattr(plugin, self.start_listeners_method):
try:
servers = getattr(plugin, self.start_listeners_method)()
except NotImplementedError:
continue
self._servers.extend(servers)
def wait(self):
try:
self._wait()
except Exception:
LOG.exception(_LE('done with wait'))
raise
def _wait(self):
LOG.debug('calling RpcWorker wait()')
for server in self._servers:
if isinstance(server, rpc_server.MessageHandlingServer):
LOG.debug('calling wait on %s', server)
server.wait()
else:
LOG.debug('NOT calling wait on %s', server)
LOG.debug('returning from RpcWorker wait()')
def stop(self):
LOG.debug('calling RpcWorker stop()')
for server in self._servers:
if isinstance(server, rpc_server.MessageHandlingServer):
LOG.debug('calling stop on %s', server)
server.stop()
@staticmethod
def reset():
config.reset_service()
class RpcReportsWorker(RpcWorker):
start_listeners_method = 'start_rpc_state_reports_listener'
def _get_rpc_workers():
plugin = directory.get_plugin()
service_plugins = directory.get_plugins().values()
if cfg.CONF.rpc_workers < 1:
cfg.CONF.set_override('rpc_workers', 1)
# If 0 < rpc_workers then start_rpc_listeners would be called in a
# subprocess and we cannot simply catch the NotImplementedError. It is
# simpler to check this up front by testing whether the plugin supports
# multiple RPC workers.
if not plugin.rpc_workers_supported():
LOG.debug("Active plugin doesn't implement start_rpc_listeners")
if 0 < cfg.CONF.rpc_workers:
LOG.error(_LE("'rpc_workers = %d' ignored because "
"start_rpc_listeners is not implemented."),
cfg.CONF.rpc_workers)
raise NotImplementedError()
# passing service plugins only, because core plugin is among them
rpc_workers = [RpcWorker(service_plugins,
worker_process_count=cfg.CONF.rpc_workers)]
if (cfg.CONF.rpc_state_report_workers > 0 and
plugin.rpc_state_report_workers_supported()):
rpc_workers.append(
RpcReportsWorker(
[plugin],
worker_process_count=cfg.CONF.rpc_state_report_workers
)
)
return rpc_workers
def _get_plugins_workers():
# NOTE(twilson) get_plugins also returns the core plugin
plugins = directory.get_unique_plugins()
# TODO(twilson) Instead of defaulting here, come up with a good way to
# share a common get_workers default between NeutronPluginBaseV2 and
# ServicePluginBase
return [
plugin_worker
for plugin in plugins if hasattr(plugin, 'get_workers')
for plugin_worker in plugin.get_workers()
]
class AllServicesNeutronWorker(neutron_worker.NeutronWorker):
def __init__(self, services, worker_process_count=1):
super(AllServicesNeutronWorker, self).__init__(worker_process_count)
self._services = services
self._launcher = common_service.Launcher(cfg.CONF)
def start(self):
for srv in self._services:
self._launcher.launch_service(srv)
super(AllServicesNeutronWorker, self).start()
def stop(self):
self._launcher.stop()
def wait(self):
self._launcher.wait()
def reset(self):
self._launcher.restart()
def _start_workers(workers):
process_workers = [
plugin_worker for plugin_worker in workers
if plugin_worker.worker_process_count > 0
]
try:
if process_workers:
worker_launcher = common_service.ProcessLauncher(
cfg.CONF, wait_interval=1.0
)
# add extra process worker and spawn there all workers with
# worker_process_count == 0
thread_workers = [
plugin_worker for plugin_worker in workers
if plugin_worker.worker_process_count < 1
]
if thread_workers:
process_workers.append(
AllServicesNeutronWorker(thread_workers)
)
# dispose the whole pool before os.fork, otherwise there will
# be shared DB connections in child processes which may cause
# DB errors.
session.context_manager.dispose_pool()
for worker in process_workers:
worker_launcher.launch_service(worker,
worker.worker_process_count)
else:
worker_launcher = common_service.ServiceLauncher(cfg.CONF)
for worker in workers:
worker_launcher.launch_service(worker)
return worker_launcher
except Exception:
with excutils.save_and_reraise_exception():
LOG.exception(_LE('Unrecoverable error: please check log for '
'details.'))
def start_all_workers():
workers = _get_rpc_workers() + _get_plugins_workers()
return _start_workers(workers)
def start_rpc_workers():
rpc_workers = _get_rpc_workers()
LOG.debug('using launcher for rpc, workers=%s', cfg.CONF.rpc_workers)
return _start_workers(rpc_workers)
def start_plugins_workers():
plugins_workers = _get_plugins_workers()
return _start_workers(plugins_workers)
def _get_api_workers():
workers = cfg.CONF.api_workers
if workers is None:
workers = processutils.get_worker_count()
return workers
def _run_wsgi(app_name):
app = config.load_paste_app(app_name)
if not app:
LOG.error(_LE('No known API applications configured.'))
return
return run_wsgi_app(app)
def run_wsgi_app(app):
server = wsgi.Server("Neutron")
server.start(app, cfg.CONF.bind_port, cfg.CONF.bind_host,
workers=_get_api_workers())
LOG.info(_LI("Neutron service started, listening on %(host)s:%(port)s"),
{'host': cfg.CONF.bind_host, 'port': cfg.CONF.bind_port})
return server
class Service(n_rpc.Service):
"""Service object for binaries running on hosts.
A service takes a manager and enables rpc by listening to queues based
on topic. It also periodically runs tasks on the manager.
"""
def __init__(self, host, binary, topic, manager, report_interval=None,
periodic_interval=None, periodic_fuzzy_delay=None,
*args, **kwargs):
self.binary = binary
self.manager_class_name = manager
manager_class = importutils.import_class(self.manager_class_name)
self.manager = manager_class(host=host, *args, **kwargs)
self.report_interval = report_interval
self.periodic_interval = periodic_interval
self.periodic_fuzzy_delay = periodic_fuzzy_delay
self.saved_args, self.saved_kwargs = args, kwargs
self.timers = []
profiler.setup(binary, host)
super(Service, self).__init__(host, topic, manager=self.manager)
def start(self):
self.manager.init_host()
super(Service, self).start()
if self.report_interval:
pulse = loopingcall.FixedIntervalLoopingCall(self.report_state)
pulse.start(interval=self.report_interval,
initial_delay=self.report_interval)
self.timers.append(pulse)
if self.periodic_interval:
if self.periodic_fuzzy_delay:
initial_delay = random.randint(0, self.periodic_fuzzy_delay)
else:
initial_delay = None
periodic = loopingcall.FixedIntervalLoopingCall(
self.periodic_tasks)
periodic.start(interval=self.periodic_interval,
initial_delay=initial_delay)
self.timers.append(periodic)
self.manager.after_start()
def __getattr__(self, key):
manager = self.__dict__.get('manager', None)
return getattr(manager, key)
@classmethod
def create(cls, host=None, binary=None, topic=None, manager=None,
report_interval=None, periodic_interval=None,
periodic_fuzzy_delay=None):
"""Instantiates class and passes back application object.
:param host: defaults to cfg.CONF.host
:param binary: defaults to basename of executable
:param topic: defaults to bin_name - 'neutron-' part
:param manager: defaults to cfg.CONF.<topic>_manager
:param report_interval: defaults to cfg.CONF.report_interval
:param periodic_interval: defaults to cfg.CONF.periodic_interval
:param periodic_fuzzy_delay: defaults to cfg.CONF.periodic_fuzzy_delay
"""
if not host:
host = cfg.CONF.host
if not binary:
binary = os.path.basename(inspect.stack()[-1][1])
if not topic:
topic = binary.rpartition('neutron-')[2]
topic = topic.replace("-", "_")
if not manager:
manager = cfg.CONF.get('%s_manager' % topic, None)
if report_interval is None:
report_interval = cfg.CONF.report_interval
if periodic_interval is None:
periodic_interval = cfg.CONF.periodic_interval
if periodic_fuzzy_delay is None:
periodic_fuzzy_delay = cfg.CONF.periodic_fuzzy_delay
service_obj = cls(host, binary, topic, manager,
report_interval=report_interval,
periodic_interval=periodic_interval,
periodic_fuzzy_delay=periodic_fuzzy_delay)
return service_obj
def kill(self):
"""Destroy the service object."""
self.stop()
def stop(self):
super(Service, self).stop()
for x in self.timers:
try:
x.stop()
except Exception:
LOG.exception(_LE("Exception occurs when timer stops"))
self.timers = []
def wait(self):
super(Service, self).wait()
for x in self.timers:
try:
x.wait()
except Exception:
LOG.exception(_LE("Exception occurs when waiting for timer"))
def reset(self):
config.reset_service()
def periodic_tasks(self, raise_on_error=False):
"""Tasks to be run at a periodic interval."""
ctxt = context.get_admin_context()
self.manager.periodic_tasks(ctxt, raise_on_error=raise_on_error)
def report_state(self):
"""Update the state of this service."""
# Todo(gongysh) report state to neutron server
pass