60 lines
2.1 KiB
Python
60 lines
2.1 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright (c) 2010 Openstack, LLC.
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# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# All Rights Reserved.
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#
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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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"""
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Availability Zone Scheduler implementation
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"""
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import random
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from nova.scheduler import driver
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from nova import db
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class ZoneScheduler(driver.Scheduler):
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"""Implements Scheduler as a random node selector."""
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def hosts_up_with_zone(self, context, topic, zone):
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"""Return the list of hosts that have a running service
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for topic and availability zone (if defined).
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"""
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if zone is None:
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return self.hosts_up(context, topic)
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services = db.service_get_all_by_topic(context, topic)
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return [service.host
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for service in services
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if self.service_is_up(service)
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and service.availability_zone == zone]
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def schedule(self, context, topic, *_args, **_kwargs):
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"""Picks a host that is up at random in selected
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availability zone (if defined).
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"""
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zone = _kwargs.get('availability_zone')
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hosts = self.hosts_up_with_zone(context, topic, zone)
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if not hosts:
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raise driver.NoValidHost(_("Scheduler was unable to locate a host"
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" for this request. Is the appropriate"
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" service running?"))
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return hosts[int(random.random() * len(hosts))]
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