#
# 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.
#
from oslo_log import log
import six
import stevedore
from aodh import evaluator
from aodh.i18n import _
LOG = log.getLogger(__name__)
STATE_CHANGE = {evaluator.ALARM: 'outside their threshold.',
evaluator.OK: 'inside their threshold.',
evaluator.UNKNOWN: 'state evaluated to unknown.'}
[docs]class RuleTarget(object):
def __init__(self, rule, rule_evaluator, rule_name):
self.rule = rule
self.type = rule.get('type')
self.rule_evaluator = rule_evaluator
self.rule_name = rule_name
self.state = None
self.trending_state = None
self.statistics = None
self.evaluated = False
[docs] def evaluate(self):
# Evaluate a sub-rule of composite rule
if not self.evaluated:
LOG.debug('Evaluating %(type)s rule: %(rule)s',
{'type': self.type, 'rule': self.rule})
self.state, self.trending_state, self.statistics, __ = \
self.rule_evaluator.evaluate_rule(self.rule)
self.evaluated = True
[docs]class RuleEvaluationBase(object):
def __init__(self, rule_target):
self.rule_target = rule_target
def __str__(self):
return self.rule_target.rule_name
[docs]class OkEvaluation(RuleEvaluationBase):
def __bool__(self):
self.rule_target.evaluate()
return self.rule_target.state == evaluator.OK
__nonzero__ = __bool__
[docs]class AlarmEvaluation(RuleEvaluationBase):
def __bool__(self):
self.rule_target.evaluate()
return self.rule_target.state == evaluator.ALARM
__nonzero__ = __bool__
[docs]class AndOp(object):
def __init__(self, rule_targets):
self.rule_targets = rule_targets
def __bool__(self):
return all(self.rule_targets)
def __str__(self):
return '(' + ' and '.join(six.moves.map(str, self.rule_targets)) + ')'
__nonzero__ = __bool__
[docs]class OrOp(object):
def __init__(self, rule_targets):
self.rule_targets = rule_targets
def __bool__(self):
return any(self.rule_targets)
def __str__(self):
return '(' + ' or '.join(six.moves.map(str, self.rule_targets)) + ')'
__nonzero__ = __bool__
[docs]class CompositeEvaluator(evaluator.Evaluator):
def __init__(self, conf):
super(CompositeEvaluator, self).__init__(conf)
self.conf = conf
self._threshold_evaluators = None
self.rule_targets = []
self.rule_name_prefix = 'rule'
self.rule_num = 0
@property
def threshold_evaluators(self):
if not self._threshold_evaluators:
threshold_types = ('threshold', 'gnocchi_resources_threshold',
'gnocchi_aggregation_by_metrics_threshold',
'gnocchi_aggregation_by_resources_threshold')
self._threshold_evaluators = stevedore.NamedExtensionManager(
'aodh.evaluator', threshold_types, invoke_on_load=True,
invoke_args=(self.conf,))
return self._threshold_evaluators
def _parse_composite_rule(self, alarm_rule):
"""Parse the composite rule.
The composite rule is assembled by sub threshold rules with 'and',
'or', the form can be nested. e.g. the form of composite rule can be
like this:
{
"and": [threshold_rule0, threshold_rule1,
{'or': [threshold_rule2, threshold_rule3,
threshold_rule4, threshold_rule5]}]
}
"""
if (isinstance(alarm_rule, dict) and len(alarm_rule) == 1
and list(alarm_rule)[0] in ('and', 'or')):
and_or_key = list(alarm_rule)[0]
if and_or_key == 'and':
rules = (self._parse_composite_rule(r) for r in
alarm_rule['and'])
rules_alarm, rules_ok = zip(*rules)
return AndOp(rules_alarm), OrOp(rules_ok)
else:
rules = (self._parse_composite_rule(r) for r in
alarm_rule['or'])
rules_alarm, rules_ok = zip(*rules)
return OrOp(rules_alarm), AndOp(rules_ok)
else:
rule_evaluator = self.threshold_evaluators[alarm_rule['type']].obj
self.rule_num += 1
name = self.rule_name_prefix + str(self.rule_num)
rule = RuleTarget(alarm_rule, rule_evaluator, name)
self.rule_targets.append(rule)
return AlarmEvaluation(rule), OkEvaluation(rule)
def _reason(self, alarm, new_state, rule_target_alarm):
transition = alarm.state != new_state
reason_data = {
'type': 'composite',
'composition_form': str(rule_target_alarm)}
root_cause_rules = {}
for rule in self.rule_targets:
if rule.state == new_state:
root_cause_rules.update({rule.rule_name: rule.rule})
reason_data.update(causative_rules=root_cause_rules)
params = {'state': new_state,
'expression': str(rule_target_alarm),
'rules': ', '.join(sorted(root_cause_rules)),
'description': STATE_CHANGE[new_state]}
if transition:
reason = (_('Composite rule alarm with composition form: '
'%(expression)s transition to %(state)s, due to '
'rules: %(rules)s %(description)s') % params)
else:
reason = (_('Composite rule alarm with composition form: '
'%(expression)s remaining as %(state)s, due to '
'rules: %(rules)s %(description)s') % params)
return reason, reason_data
def _evaluate_sufficient(self, alarm, rule_target_alarm, rule_target_ok):
# Some of evaluated rules are unknown states or trending states.
for rule in self.rule_targets:
if rule.trending_state is not None:
if alarm.state == evaluator.UNKNOWN:
rule.state = rule.trending_state
elif rule.trending_state == evaluator.ALARM:
rule.state = evaluator.OK
elif rule.trending_state == evaluator.OK:
rule.state = evaluator.ALARM
else:
rule.state = alarm.state
alarm_triggered = bool(rule_target_alarm)
if alarm_triggered:
reason, reason_data = self._reason(alarm, evaluator.ALARM,
rule_target_alarm)
self._refresh(alarm, evaluator.ALARM, reason, reason_data)
return True
ok_result = bool(rule_target_ok)
if ok_result:
reason, reason_data = self._reason(alarm, evaluator.OK,
rule_target_alarm)
self._refresh(alarm, evaluator.OK, reason, reason_data)
return True
return False
[docs] def evaluate(self, alarm):
if not self.within_time_constraint(alarm):
LOG.debug('Attempted to evaluate alarm %s, but it is not '
'within its time constraint.', alarm.alarm_id)
return
LOG.debug("Evaluating composite rule alarm %s ...", alarm.alarm_id)
self.rule_targets = []
self.rule_num = 0
rule_target_alarm, rule_target_ok = self._parse_composite_rule(
alarm.rule)
sufficient = self._evaluate_sufficient(alarm, rule_target_alarm,
rule_target_ok)
if not sufficient:
for rule in self.rule_targets:
rule.evaluate()
sufficient = self._evaluate_sufficient(alarm, rule_target_alarm,
rule_target_ok)
if not sufficient:
# The following unknown situations is like these:
# 1. 'unknown' and 'alarm'
# 2. 'unknown' or 'ok'
reason, reason_data = self._reason(alarm, evaluator.UNKNOWN,
rule_target_alarm)
if alarm.state != evaluator.UNKNOWN:
self._refresh(alarm, evaluator.UNKNOWN, reason, reason_data)
else:
LOG.debug(reason)