deb-ceilometer/ceilometer/plugin.py
Nejc Saje b6e1c7e5dc Migrate the rest of the central agent pollsters to use discoveries
Currently, not all the central agent pollsters use discoveries.
In order to enable horizontal scaling, all pollsters must use
discoveries so the resources can be partitioned across the pool
of running central agents.

For pollsters that don't poll specific resources, but only poll
general info from services, we treat the service endpoints as
resources. So in the case of Glance, there will be only one
resource available for all the pollsters (a Glance endpoint).
If there are multiple agents running, only one will be assigned
that endpoint and only one will poll Glance API.

DocImpact
Co-Authored-By: Dina Belova <dbelova@mirantis.com>
Closes-Bug: #1364352
Change-Id: I8f3b228db9aacf3a7cc4b719c50013cc30d5aa79
2014-09-08 13:38:10 -04:00

189 lines
6.7 KiB
Python

#
# Copyright 2012 New Dream Network, LLC (DreamHost)
#
# Author: Doug Hellmann <doug.hellmann@dreamhost.com>
#
# 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.
"""Base class for plugins.
"""
import abc
import collections
import fnmatch
import oslo.messaging
import six
from ceilometer import messaging
from ceilometer.openstack.common import context
from ceilometer.openstack.common.gettextutils import _
from ceilometer.openstack.common import log
LOG = log.getLogger(__name__)
ExchangeTopics = collections.namedtuple('ExchangeTopics',
['exchange', 'topics'])
class PluginBase(object):
"""Base class for all plugins."""
@six.add_metaclass(abc.ABCMeta)
class NotificationBase(PluginBase):
"""Base class for plugins that support the notification API."""
def __init__(self, pipeline_manager):
super(NotificationBase, self).__init__()
self.pipeline_manager = pipeline_manager
@abc.abstractproperty
def event_types(self):
"""Return a sequence of strings.
Strings are defining the event types to be given to this plugin.
"""
def get_targets(self, conf):
"""Return a sequence of oslo.messaging.Target.
Sequence is defining the exchange and topics to be connected for this
plugin.
:param conf: Configuration.
"""
# TODO(sileht): Backwards compatibility, remove in J+1
if hasattr(self, 'get_exchange_topics'):
LOG.warn(_('get_exchange_topics API of NotificationPlugin is'
'deprecated, implements get_targets instead.'))
targets = []
for exchange, topics in self.get_exchange_topics(conf):
targets.extend(oslo.messaging.Target(topic=topic,
exchange=exchange)
for topic in topics)
return targets
@abc.abstractmethod
def process_notification(self, message):
"""Return a sequence of Counter instances for the given message.
:param message: Message to process.
"""
@staticmethod
def _handle_event_type(event_type, event_type_to_handle):
"""Check whether event_type should be handled.
It is according to event_type_to_handle.
"""
return any(map(lambda e: fnmatch.fnmatch(event_type, e),
event_type_to_handle))
def info(self, ctxt, publisher_id, event_type, payload, metadata):
"""RPC endpoint for notification messages
When another service sends a notification over the message
bus, this method receives it.
:param ctxt: oslo.messaging context
:param publisher_id: publisher of the notification
:param event_type: type of notification
:param payload: notification payload
:param metadata: metadata about the notification
"""
notification = messaging.convert_to_old_notification_format(
'info', ctxt, publisher_id, event_type, payload, metadata)
self.to_samples_and_publish(context.get_admin_context(), notification)
def to_samples_and_publish(self, context, notification):
"""Return samples produced by *process_notification*.
Samples produced for the given notification.
:param context: Execution context from the service or RPC call
:param notification: The notification to process.
"""
# TODO(sileht): this will be moved into oslo.messaging
# see oslo.messaging bp notification-dispatcher-filter
if not self._handle_event_type(notification['event_type'],
self.event_types):
return
with self.pipeline_manager.publisher(context) as p:
p(list(self.process_notification(notification)))
@six.add_metaclass(abc.ABCMeta)
class PollsterBase(PluginBase):
"""Base class for plugins that support the polling API."""
@abc.abstractproperty
def default_discovery(self):
"""Default discovery to use for this pollster.
There are three ways a pollster can get a list of resources to poll,
listed here in ascending order of precedence:
1. from the per-agent discovery,
2. from the per-pollster discovery (defined here)
3. from the per-pipeline configured discovery and/or per-pipeline
configured static resources.
If a pollster should only get resources from #1 or #3, this property
should be set to None.
"""
@abc.abstractmethod
def get_samples(self, manager, cache, resources):
"""Return a sequence of Counter instances from polling the resources.
:param manager: The service manager class invoking the plugin.
:param cache: A dictionary to allow pollsters to pass data
between themselves when recomputing it would be
expensive (e.g., asking another service for a
list of objects).
:param resources: A list of resources the pollster will get data
from. It's up to the specific pollster to decide
how to use it. It is usually supplied by a discovery,
see ``default_discovery`` for more information.
"""
@six.add_metaclass(abc.ABCMeta)
class DiscoveryBase(object):
@abc.abstractmethod
def discover(self, param=None):
"""Discover resources to monitor.
:param param: an optional parameter to guide the discovery
"""
@property
def group_id(self):
"""Return group id of this discovery.
All running recoveries with the same group_id should return the same
set of resources at a given point in time. By default, a discovery is
put into a global group, meaning that all discoveries of its type
running anywhere in the cloud, return the same set of resources.
This property can be overridden to provide correct grouping of
localized discoveries. For example, compute discovery is localized
to a host, which is reflected in its group_id.
A None value signifies that this discovery does not want to be part
of workload partitioning at all.
"""
return 'global'