Refactor threshold evaluator

This change creates a base class for evaluator.

The alarm service load all evaluators.
A evaluator needs to implement abstract method of this base class.

The alarm service now check in alarm.type use the right extension to
evaluate the alarm.

The previous threshold evaluator code has been moved into the threshold
extension.

Related to blueprint alarming-logical-combination

Change-Id: If6057b7db1e894333e6e9f1edb41ab75bc2c4444

ceilometer/alarm/evaluator/__init__.py

@@ -0,0 +1,78 @@
+# -*- encoding: utf-8 -*-
+#
+# Copyright © 2013 eNovance <licensing@enovance.com>
+#
+# Authors: Mehdi Abaakouk <mehdi.abaakouk@enovance.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.
+
+
+import abc
+
+from oslo.config import cfg
+
+from ceilometerclient import client as ceiloclient
+
+from ceilometer.openstack.common import log
+from ceilometer.openstack.common.gettextutils import _
+
+LOG = log.getLogger(__name__)
+
+
+class Evaluator(object):
+    """Base class for alarm rule evaluator plugins."""
+
+    __metaclass__ = abc.ABCMeta
+
+    def __init__(self, notifier):
+        self.notifier = notifier
+        self.api_client = None
+
+    @property
+    def _client(self):
+        """Construct or reuse an authenticated API client."""
+        if not self.api_client:
+            auth_config = cfg.CONF.service_credentials
+            creds = dict(
+                os_auth_url=auth_config.os_auth_url,
+                os_tenant_name=auth_config.os_tenant_name,
+                os_password=auth_config.os_password,
+                os_username=auth_config.os_username,
+                cacert=auth_config.os_cacert,
+                endpoint_type=auth_config.os_endpoint_type,
+            )
+            self.api_client = ceiloclient.get_client(2, **creds)
+        return self.api_client
+
+    def _refresh(self, alarm, state, reason):
+        """Refresh alarm state."""
+        try:
+            previous = alarm.state
+            if previous != state:
+                LOG.info(_('alarm %(id)s transitioning to %(state)s because '
+                           '%(reason)s') % {'id': alarm.alarm_id,
+                                            'state': state,
+                                            'reason': reason})
+
+                self._client.alarms.update(alarm.alarm_id, **dict(state=state))
+            alarm.state = state
+            if self.notifier:
+                self.notifier.notify(alarm, previous, reason)
+        except Exception:
+            # retry will occur naturally on the next evaluation
+            # cycle (unless alarm state reverts in the meantime)
+            LOG.exception(_('alarm state update failed'))
+
+    @abc.abstractmethod
+    def evaluate(self, alarm):
+        pass

ceilometer/alarm/threshold_evaluation.py → ceilometer/alarm/evaluator/threshold.py

@@ -3,6 +3,7 @@
 # Copyright © 2013 Red Hat, Inc
 #
 # Author: Eoghan Glynn <eglynn@redhat.com>
+# Author: Mehdi Abaakouk <mehdi.abaakouk@enovance.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
@@ -19,11 +20,9 @@
 import datetime
 import operator
 
-from oslo.config import cfg
-
+from ceilometer.alarm import evaluator
 from ceilometer.openstack.common import log
 from ceilometer.openstack.common import timeutils
-from ceilometerclient import client as ceiloclient
 from ceilometer.openstack.common.gettextutils import _
 
 LOG = log.getLogger(__name__)
@@ -42,10 +41,7 @@
 ALARM = 'alarm'
 
 
-class Evaluator(object):
-    """This class implements the basic alarm threshold evaluation
-       logic.
-    """
+class ThresholdEvaluator(evaluator.Evaluator):
 
     # the sliding evaluation window is extended to allow
     # for reporting/ingestion lag
@@ -55,31 +51,6 @@ class Evaluator(object):
     # avoid unknown state
     quorum = 1
 
-    def __init__(self, notifier=None):
-        self.alarms = []
-        self.notifier = notifier
-        self.api_client = None
-
-    def assign_alarms(self, alarms):
-        """Assign alarms to be evaluated."""
-        self.alarms = alarms
-
-    @property
-    def _client(self):
-        """Construct or reuse an authenticated API client."""
-        if not self.api_client:
-            auth_config = cfg.CONF.service_credentials
-            creds = dict(
-                os_auth_url=auth_config.os_auth_url,
-                os_tenant_name=auth_config.os_tenant_name,
-                os_password=auth_config.os_password,
-                os_username=auth_config.os_username,
-                cacert=auth_config.os_cacert,
-                endpoint_type=auth_config.os_endpoint_type,
-            )
-            self.api_client = ceiloclient.get_client(2, **creds)
-        return self.api_client
-
     @classmethod
     def _bound_duration(cls, alarm, constraints):
         """Bound the duration of the statistics query."""
@@ -118,25 +89,6 @@ def _statistics(self, alarm, query):
             LOG.exception(_('alarm stats retrieval failed'))
             return []
 
-    def _refresh(self, alarm, state, reason):
-        """Refresh alarm state."""
-        try:
-            previous = alarm.state
-            if previous != state:
-                LOG.info(_('alarm %(id)s transitioning to %(state)s because '
-                           '%(reason)s') % {'id': alarm.alarm_id,
-                                            'state': state,
-                                            'reason': reason})
-
-                self._client.alarms.update(alarm.alarm_id, **dict(state=state))
-            alarm.state = state
-            if self.notifier:
-                self.notifier.notify(alarm, previous, reason)
-        except Exception:
-            # retry will occur naturally on the next evaluation
-            # cycle (unless alarm state reverts in the meantime)
-            LOG.exception(_('alarm state update failed'))
-
     def _sufficient(self, alarm, statistics):
         """Ensure there is sufficient data for evaluation,
            transitioning to unknown otherwise.
@@ -194,40 +146,27 @@ def _transition(self, alarm, statistics, compared):
             reason = self._reason(alarm, statistics, distilled, state)
             self._refresh(alarm, state, reason)
 
-    def evaluate(self):
-        """Evaluate the alarms assigned to this evaluator."""
-
-        LOG.info(_('initiating evaluation cycle on %d alarms') %
-                 len(self.alarms))
-
-        for alarm in self.alarms:
-
-            if not alarm.enabled:
-                LOG.debug(_('skipping alarm %s') % alarm.alarm_id)
-                continue
-            LOG.debug(_('evaluating alarm %s') % alarm.alarm_id)
-
-            query = self._bound_duration(
-                alarm,
-                alarm.rule['query']
-            )
-
-            statistics = self._sanitize(
-                alarm,
-                self._statistics(alarm, query)
-            )
-
-            if self._sufficient(alarm, statistics):
-
-                def _compare(stat):
-                    op = COMPARATORS[alarm.rule['comparison_operator']]
-                    value = getattr(stat, alarm.rule['statistic'])
-                    limit = alarm.rule['threshold']
-                    LOG.debug(_('comparing value %(value)s against threshold'
-                                ' %(limit)s') %
-                              {'value': value, 'limit': limit})
-                    return op(value, limit)
-
-                self._transition(alarm,
-                                 statistics,
-                                 list(map(_compare, statistics)))
+    def evaluate(self, alarm):
+        query = self._bound_duration(
+            alarm,
+            alarm.rule['query']
+        )
+
+        statistics = self._sanitize(
+            alarm,
+            self._statistics(alarm, query)
+        )
+
+        if self._sufficient(alarm, statistics):
+            def _compare(stat):
+                op = COMPARATORS[alarm.rule['comparison_operator']]
+                value = getattr(stat, alarm.rule['statistic'])
+                limit = alarm.rule['threshold']
+                LOG.debug(_('comparing value %(value)s against threshold'
+                            ' %(limit)s') %
+                          {'value': value, 'limit': limit})
+                return op(value, limit)
+
+            self._transition(alarm,
+                             statistics,
+                             map(_compare, statistics))

ceilometer/alarm/service.py

@@ -33,11 +33,13 @@
 
 
 OPTS = [
-    cfg.IntOpt('threshold_evaluation_interval',
+    cfg.IntOpt('evaluation_interval',
                default=60,
-               help='Period of threshold evaluation cycle, should'
+               help='Period of evaluation cycle, should'
                     ' be >= than configured pipeline interval for'
-                    ' collection of underlying metrics.'),
+                    ' collection of underlying metrics.',
+               deprecated_opts=[cfg.DeprecatedOpt(
+                   'threshold_evaluation_interval', group='alarm')])
 ]
 
 cfg.CONF.register_opts(OPTS, group='alarm')
@@ -49,54 +51,68 @@
 
 class SingletonAlarmService(os_service.Service):
 
-    ALARM_NAMESPACE = 'ceilometer.alarm'
+    EXTENSIONS_NAMESPACE = "ceilometer.alarm.evaluator"
 
     def __init__(self):
         super(SingletonAlarmService, self).__init__()
-        self.extension_manager = extension.ExtensionManager(
-            namespace=self.ALARM_NAMESPACE,
+        self.api_client = None
+        self.evaluators = extension.ExtensionManager(
+            self.EXTENSIONS_NAMESPACE,
             invoke_on_load=True,
-            invoke_args=(rpc_alarm.RPCAlarmNotifier(),)
-        )
+            invoke_args=(rpc_alarm.RPCAlarmNotifier(),))
+        self.supported_evaluators = [ext.name for ext in
+                                     self.evaluators.extensions]
 
     def start(self):
         super(SingletonAlarmService, self).start()
-        for ext in self.extension_manager.extensions:
-            if ext.name == 'threshold_eval':
-                self.threshold_eval = ext.obj
-                interval = cfg.CONF.alarm.threshold_evaluation_interval
-                args = [ext.obj, self._client()]
-                self.tg.add_timer(
-                    interval,
-                    self._evaluate_all_alarms,
-                    0,
-                    *args)
-                break
+        interval = cfg.CONF.alarm.evaluation_interval
+        self.tg.add_timer(
+            interval,
+            self._evaluate_all_alarms,
+            0)
         # Add a dummy thread to have wait() working
         self.tg.add_timer(604800, lambda: None)
 
-    @staticmethod
-    def _client():
-        auth_config = cfg.CONF.service_credentials
-        creds = dict(
-            os_auth_url=auth_config.os_auth_url,
-            os_tenant_name=auth_config.os_tenant_name,
-            os_password=auth_config.os_password,
-            os_username=auth_config.os_username,
-            cacert=auth_config.os_cacert,
-            endpoint_type=auth_config.os_endpoint_type,
-        )
-        return ceiloclient.get_client(2, **creds)
-
-    @staticmethod
-    def _evaluate_all_alarms(threshold_eval, api_client):
+    @property
+    def _client(self):
+        """Construct or reuse an authenticated API client."""
+        if not self.api_client:
+            auth_config = cfg.CONF.service_credentials
+            creds = dict(
+                os_auth_url=auth_config.os_auth_url,
+                os_tenant_name=auth_config.os_tenant_name,
+                os_password=auth_config.os_password,
+                os_username=auth_config.os_username,
+                cacert=auth_config.os_cacert,
+                endpoint_type=auth_config.os_endpoint_type,
+            )
+            self.api_client = ceiloclient.get_client(2, **creds)
+        return self.api_client
+
+    def _evaluate_all_alarms(self):
         try:
-            alarms = api_client.alarms.list()
-            threshold_eval.assign_alarms(alarms)
-            threshold_eval.evaluate()
+            alarms = self._client.alarms.list()
+            LOG.info(_('initiating evaluation cycle on %d alarms') %
+                     len(alarms))
+            for alarm in alarms:
+                self._evaluate_alarm(alarm)
         except Exception:
             LOG.exception(_('threshold evaluation cycle failed'))
 
+    def _evaluate_alarm(self, alarm):
+        """Evaluate the alarms assigned to this evaluator."""
+        if not alarm.enabled:
+            LOG.debug(_('skipping alarm %s: alarm disabled') %
+                      alarm.alarm_id)
+            return
+        if alarm.type not in self.supported_evaluators:
+            LOG.debug(_('skipping alarm %s: type unsupported') %
+                      alarm.alarm_id)
+            return
+
+        LOG.debug(_('evaluating alarm %s') % alarm.alarm_id)
+        self.evaluators[alarm.type].obj.evaluate(alarm)
+
 
 def singleton_alarm():
     prepare_service()

etc/ceilometer/ceilometer.conf.sample

@@ -610,10 +610,10 @@
 # Options defined in ceilometer.alarm.service
 #
 
-# Period of threshold evaluation cycle, should be >= than
-# configured pipeline interval for collection of underlying
-# metrics. (integer value)
-#threshold_evaluation_interval=60
+# Period of evaluation cycle, should be >= than configured
+# pipeline interval for collection of underlying metrics.
+# (integer value)
+#evaluation_interval=60
 
 
 #

setup.cfg

@@ -102,8 +102,8 @@ ceilometer.publisher =
     udp = ceilometer.publisher.udp:UDPPublisher
     file = ceilometer.publisher.file:FilePublisher
 
-ceilometer.alarm =
-    threshold_eval = ceilometer.alarm.threshold_evaluation:Evaluator
+ceilometer.alarm.evaluator =
+    threshold = ceilometer.alarm.evaluator.threshold:ThresholdEvaluator
 
 ceilometer.alarm.notifier =
     log = ceilometer.alarm.notifier.log:LogAlarmNotifier
@@ -129,6 +129,7 @@ ceilometer.dispatcher =
     database = ceilometer.collector.dispatcher.database:DatabaseDispatcher
     file = ceilometer.collector.dispatcher.file:FileDispatcher
 
+
 [build_sphinx]
 all_files = 1
 build-dir = doc/build