OpenStack library for messaging
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# Copyright 2011 OpenStack Foundation.
# All Rights Reserved.
# Copyright 2013 Red Hat, Inc.
#
# 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 abc
import logging
import uuid
from oslo.config import cfg
import six
from stevedore import named
from oslo.messaging.openstack.common import timeutils
from oslo.messaging import serializer as msg_serializer
_notifier_opts = [
cfg.MultiStrOpt('notification_driver',
default=[],
help='Driver or drivers to handle sending notifications.'),
cfg.ListOpt('notification_topics',
default=['notifications', ],
deprecated_name='topics',
deprecated_group='rpc_notifier2',
help='AMQP topic used for OpenStack notifications.'),
]
_LOG = logging.getLogger(__name__)
@six.add_metaclass(abc.ABCMeta)
class _Driver(object):
def __init__(self, conf, topics, transport):
self.conf = conf
self.topics = topics
self.transport = transport
@abc.abstractmethod
def notify(self, ctxt, msg, priority, retry):
pass
class Notifier(object):
"""Send notification messages.
The Notifier class is used for sending notification messages over a
messaging transport or other means.
Notification messages follow the following format::
{'message_id': six.text_type(uuid.uuid4()),
'publisher_id': 'compute.host1',
'timestamp': timeutils.utcnow(),
'priority': 'WARN',
'event_type': 'compute.create_instance',
'payload': {'instance_id': 12, ... }}
A Notifier object can be instantiated with a transport object and a
publisher ID:
notifier = notifier.Notifier(get_transport(CONF), 'compute')
and notifications are sent via drivers chosen with the notification_driver
config option and on the topics chosen with the notification_topics config
option.
Alternatively, a Notifier object can be instantiated with a specific
driver or topic::
notifier = notifier.Notifier(RPC_TRANSPORT,
'compute.host',
driver='messaging',
topic='notifications')
Notifier objects are relatively expensive to instantiate (mostly the cost
of loading notification drivers), so it is possible to specialize a given
Notifier object with a different publisher id using the prepare() method::
notifier = notifier.prepare(publisher_id='compute')
notifier.info(ctxt, event_type, payload)
"""
def __init__(self, transport, publisher_id=None,
driver=None, topic=None,
serializer=None, retry=None):
"""Construct a Notifier object.
:param transport: the transport to use for sending messages
:type transport: oslo.messaging.Transport
:param publisher_id: field in notifications sent, e.g. 'compute.host1'
:type publisher_id: str
:param driver: a driver to lookup from oslo.messaging.notify.drivers
:type driver: str
:param topic: the topic which to send messages on
:type topic: str
:param serializer: an optional entity serializer
:type serializer: Serializer
:param retry: an connection retries configuration
None or -1 means to retry forever
0 means no retry
N means N retries
:type retry: int
"""
transport.conf.register_opts(_notifier_opts)
self.transport = transport
self.publisher_id = publisher_id
self.retry = retry
self._driver_names = ([driver] if driver is not None
else transport.conf.notification_driver)
self._topics = ([topic] if topic is not None
else transport.conf.notification_topics)
self._serializer = serializer or msg_serializer.NoOpSerializer()
self._driver_mgr = named.NamedExtensionManager(
'oslo.messaging.notify.drivers',
names=self._driver_names,
invoke_on_load=True,
invoke_args=[transport.conf],
invoke_kwds={
'topics': self._topics,
'transport': self.transport,
}
)
_marker = object()
def prepare(self, publisher_id=_marker, retry=_marker):
"""Return a specialized Notifier instance.
Returns a new Notifier instance with the supplied publisher_id. Allows
sending notifications from multiple publisher_ids without the overhead
of notification driver loading.
:param publisher_id: field in notifications sent, e.g. 'compute.host1'
:type publisher_id: str
:param retry: an connection retries configuration
None or -1 means to retry forever
0 means no retry
N means N retries
:type retry: int
"""
return _SubNotifier._prepare(self, publisher_id, retry=retry)
def _notify(self, ctxt, event_type, payload, priority, publisher_id=None,
retry=None):
payload = self._serializer.serialize_entity(ctxt, payload)
ctxt = self._serializer.serialize_context(ctxt)
msg = dict(message_id=six.text_type(uuid.uuid4()),
publisher_id=publisher_id or self.publisher_id,
event_type=event_type,
priority=priority,
payload=payload,
timestamp=six.text_type(timeutils.utcnow()))
def do_notify(ext):
try:
ext.obj.notify(ctxt, msg, priority, retry or self.retry)
except Exception as e:
_LOG.exception("Problem '%(e)s' attempting to send to "
"notification system. Payload=%(payload)s",
dict(e=e, payload=payload))
if self._driver_mgr.extensions:
self._driver_mgr.map(do_notify)
def audit(self, ctxt, event_type, payload):
"""Send a notification at audit level.
:param ctxt: a request context dict
:type ctxt: dict
:param event_type: describes the event, e.g. 'compute.create_instance'
:type event_type: str
:param payload: the notification payload
:type payload: dict
:raises: MessageDeliveryFailure
"""
self._notify(ctxt, event_type, payload, 'AUDIT')
def debug(self, ctxt, event_type, payload):
"""Send a notification at debug level.
:param ctxt: a request context dict
:type ctxt: dict
:param event_type: describes the event, e.g. 'compute.create_instance'
:type event_type: str
:param payload: the notification payload
:type payload: dict
:raises: MessageDeliveryFailure
"""
self._notify(ctxt, event_type, payload, 'DEBUG')
def info(self, ctxt, event_type, payload):
"""Send a notification at info level.
:param ctxt: a request context dict
:type ctxt: dict
:param event_type: describes the event, e.g. 'compute.create_instance'
:type event_type: str
:param payload: the notification payload
:type payload: dict
:raises: MessageDeliveryFailure
"""
self._notify(ctxt, event_type, payload, 'INFO')
def warn(self, ctxt, event_type, payload):
"""Send a notification at warning level.
:param ctxt: a request context dict
:type ctxt: dict
:param event_type: describes the event, e.g. 'compute.create_instance'
:type event_type: str
:param payload: the notification payload
:type payload: dict
:raises: MessageDeliveryFailure
"""
self._notify(ctxt, event_type, payload, 'WARN')
warning = warn
def error(self, ctxt, event_type, payload):
"""Send a notification at error level.
:param ctxt: a request context dict
:type ctxt: dict
:param event_type: describes the event, e.g. 'compute.create_instance'
:type event_type: str
:param payload: the notification payload
:type payload: dict
:raises: MessageDeliveryFailure
"""
self._notify(ctxt, event_type, payload, 'ERROR')
def critical(self, ctxt, event_type, payload):
"""Send a notification at critical level.
:param ctxt: a request context dict
:type ctxt: dict
:param event_type: describes the event, e.g. 'compute.create_instance'
:type event_type: str
:param payload: the notification payload
:type payload: dict
:raises: MessageDeliveryFailure
"""
self._notify(ctxt, event_type, payload, 'CRITICAL')
def sample(self, ctxt, event_type, payload):
"""Send a notification at sample level.
Sample notifications are for high-frequency events
that typically contain small payloads. eg: "CPU = 70%"
Not all drivers support the sample level
(log, for example) so these could be dropped.
:param ctxt: a request context dict
:type ctxt: dict
:param event_type: describes the event, e.g. 'compute.create_instance'
:type event_type: str
:param payload: the notification payload
:type payload: dict
:raises: MessageDeliveryFailure
"""
self._notify(ctxt, event_type, payload, 'SAMPLE')
class _SubNotifier(Notifier):
_marker = Notifier._marker
def __init__(self, base, publisher_id, retry):
self._base = base
self.transport = base.transport
self.publisher_id = publisher_id
self.retry = retry
self._serializer = self._base._serializer
self._driver_mgr = self._base._driver_mgr
def _notify(self, ctxt, event_type, payload, priority):
super(_SubNotifier, self)._notify(ctxt, event_type, payload, priority)
@classmethod
def _prepare(cls, base, publisher_id=_marker, retry=_marker):
if publisher_id is cls._marker:
publisher_id = base.publisher_id
if retry is cls._marker:
retry = base.retry
return cls(base, publisher_id, retry=retry)