b76881b8bc
There are cases where it takes a long time to create a new resource as requested by the scaling operation on an ASG resource, for instance, a nova server creation followed by a complex SoftwareDeployment. During this process, additional alarms may come in but failed to be blocked by the current cooldown checking mechanism because the very first timestamp has yet to be generated. This is leading to unexpected size adjustment to the ASG. This patch augments the existing cooldown checking mechanism with a scaling-in-progress test so that additional alarms arriving during the very first scaling operation will be ignored. Change-Id: Ib8aa83eed366df7097c9cbb9247eca866ae4b620 Closes-Bug: #1375156
64 lines
2.5 KiB
Python
64 lines
2.5 KiB
Python
#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from oslo_utils import timeutils
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import six
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class CooldownMixin(object):
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'''
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Utility class to encapsulate Cooldown related logic which is shared
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between AutoScalingGroup and ScalingPolicy. This logic includes both
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cooldown timestamp comparing and scaling in progress checking.
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'''
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def _cooldown_inprogress(self):
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inprogress = False
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try:
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# Negative values don't make sense, so they are clamped to zero
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cooldown = max(0, self.properties[self.COOLDOWN])
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except TypeError:
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# If not specified, it will be None, same as cooldown == 0
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cooldown = 0
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metadata = self.metadata_get()
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if metadata.get('scaling_in_progress'):
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return True
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if 'cooldown' not in metadata:
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# Note: this is for supporting old version cooldown checking
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if metadata and cooldown != 0:
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last_adjust = next(six.iterkeys(metadata))
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if not timeutils.is_older_than(last_adjust, cooldown):
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inprogress = True
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elif cooldown != 0:
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last_adjust = next(six.iterkeys(metadata['cooldown']))
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if not timeutils.is_older_than(last_adjust, cooldown):
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inprogress = True
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if not inprogress:
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metadata['scaling_in_progress'] = True
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self.metadata_set(metadata)
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return inprogress
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def _cooldown_timestamp(self, reason):
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# Save cooldown timestamp into metadata and clean the
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# scaling_in_progress state.
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# If we wanted to implement the AutoScaling API like AWS does,
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# we could maintain event history here, but since we only need
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# the latest event for cooldown, just store that for now
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metadata = self.metadata_get()
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metadata['cooldown'] = {timeutils.utcnow().isoformat(): reason}
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metadata['scaling_in_progress'] = False
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self.metadata_set(metadata)
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