68 lines
2.7 KiB
Python
68 lines
2.7 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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"""Utility class to encapsulate Cooldown related logic.
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This class is shared between AutoScalingGroup and ScalingPolicy.
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This logic includes both cooldown timestamp comparing and scaling in
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progress checking.
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"""
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def _is_scaling_allowed(self):
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metadata = self.metadata_get()
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if metadata.get('scaling_in_progress'):
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return 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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if cooldown != 0:
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try:
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if 'cooldown' not in metadata:
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# Note: this is for supporting old version cooldown logic
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if metadata:
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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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return False
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else:
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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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return False
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except ValueError:
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# occurs when metadata has only {scaling_in_progress: False}
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pass
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# Assumes _finished_scaling is called
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# after the scaling operation completes
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metadata['scaling_in_progress'] = True
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self.metadata_set(metadata)
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return True
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def _finished_scaling(self, cooldown_reason, size_changed=True):
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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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if size_changed:
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now = timeutils.utcnow().isoformat()
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metadata['cooldown'] = {now: cooldown_reason}
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metadata['scaling_in_progress'] = False
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self.metadata_set(metadata)
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