86 lines
3.4 KiB
Python
86 lines
3.4 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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Chance (Random) Scheduler implementation
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"""
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import random
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from nova import exception
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from nova.scheduler import driver
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class ChanceScheduler(driver.Scheduler):
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"""Implements Scheduler as a random node selector."""
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def _filter_hosts(self, request_spec, hosts, **kwargs):
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"""Filter a list of hosts based on request_spec."""
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filter_properties = kwargs.get('filter_properties', {})
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ignore_hosts = filter_properties.get('ignore_hosts', [])
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hosts = [host for host in hosts if host not in ignore_hosts]
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return hosts
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def _schedule(self, context, topic, request_spec, **kwargs):
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"""Picks a host that is up at random."""
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elevated = context.elevated()
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hosts = self.hosts_up(elevated, topic)
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if not hosts:
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msg = _("Is the appropriate service running?")
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raise exception.NoValidHost(reason=msg)
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hosts = self._filter_hosts(request_spec, hosts, **kwargs)
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if not hosts:
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msg = _("Could not find another compute")
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raise exception.NoValidHost(reason=msg)
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return hosts[int(random.random() * len(hosts))]
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def schedule(self, context, topic, method, *_args, **kwargs):
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"""Picks a host that is up at random."""
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host = self._schedule(context, topic, None, **kwargs)
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driver.cast_to_host(context, topic, host, method, **kwargs)
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def schedule_run_instance(self, context, request_spec, reservations,
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*_args, **kwargs):
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"""Create and run an instance or instances"""
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num_instances = request_spec.get('num_instances', 1)
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instances = []
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for num in xrange(num_instances):
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host = self._schedule(context, 'compute', request_spec, **kwargs)
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request_spec['instance_properties']['launch_index'] = num
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instance = self.create_instance_db_entry(context, request_spec,
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reservations)
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driver.cast_to_compute_host(context, host,
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'run_instance', instance_uuid=instance['uuid'], **kwargs)
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instances.append(driver.encode_instance(instance))
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# So if we loop around, create_instance_db_entry will actually
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# create a new entry, instead of assume it's been created
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# already
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del request_spec['instance_properties']['uuid']
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return instances
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def schedule_prep_resize(self, context, request_spec, *args, **kwargs):
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"""Select a target for resize."""
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host = self._schedule(context, 'compute', request_spec, **kwargs)
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driver.cast_to_compute_host(context, host, 'prep_resize', **kwargs)
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