145 lines
5.7 KiB
Python
145 lines
5.7 KiB
Python
# Copyright (c) 2011 OpenStack Foundation
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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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The FilterScheduler is for creating instances locally.
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You can customize this scheduler by specifying your own Host Filters and
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Weighing Functions.
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"""
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import random
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from oslo_log import log as logging
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from six.moves import range
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import nova.conf
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from nova import exception
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from nova.i18n import _
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from nova import rpc
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from nova.scheduler import driver
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from nova.scheduler import scheduler_options
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CONF = nova.conf.CONF
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LOG = logging.getLogger(__name__)
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class FilterScheduler(driver.Scheduler):
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"""Scheduler that can be used for filtering and weighing."""
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def __init__(self, *args, **kwargs):
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super(FilterScheduler, self).__init__(*args, **kwargs)
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self.options = scheduler_options.SchedulerOptions()
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self.notifier = rpc.get_notifier('scheduler')
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def select_destinations(self, context, spec_obj):
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"""Selects a filtered set of hosts and nodes."""
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self.notifier.info(
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context, 'scheduler.select_destinations.start',
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dict(request_spec=spec_obj.to_legacy_request_spec_dict()))
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num_instances = spec_obj.num_instances
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selected_hosts = self._schedule(context, spec_obj)
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# Couldn't fulfill the request_spec
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if len(selected_hosts) < num_instances:
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# NOTE(Rui Chen): If multiple creates failed, set the updated time
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# of selected HostState to None so that these HostStates are
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# refreshed according to database in next schedule, and release
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# the resource consumed by instance in the process of selecting
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# host.
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for host in selected_hosts:
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host.obj.updated = None
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# Log the details but don't put those into the reason since
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# we don't want to give away too much information about our
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# actual environment.
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LOG.debug('There are %(hosts)d hosts available but '
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'%(num_instances)d instances requested to build.',
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{'hosts': len(selected_hosts),
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'num_instances': num_instances})
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reason = _('There are not enough hosts available.')
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raise exception.NoValidHost(reason=reason)
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dests = [dict(host=host.obj.host, nodename=host.obj.nodename,
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limits=host.obj.limits) for host in selected_hosts]
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self.notifier.info(
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context, 'scheduler.select_destinations.end',
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dict(request_spec=spec_obj.to_legacy_request_spec_dict()))
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return dests
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def _get_configuration_options(self):
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"""Fetch options dictionary. Broken out for testing."""
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return self.options.get_configuration()
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def _schedule(self, context, spec_obj):
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"""Returns a list of hosts that meet the required specs,
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ordered by their fitness.
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"""
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elevated = context.elevated()
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config_options = self._get_configuration_options()
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# Find our local list of acceptable hosts by repeatedly
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# filtering and weighing our options. Each time we choose a
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# host, we virtually consume resources on it so subsequent
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# selections can adjust accordingly.
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# Note: remember, we are using an iterator here. So only
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# traverse this list once. This can bite you if the hosts
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# are being scanned in a filter or weighing function.
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hosts = self._get_all_host_states(elevated)
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selected_hosts = []
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num_instances = spec_obj.num_instances
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# NOTE(sbauza): Adding one field for any out-of-tree need
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spec_obj.config_options = config_options
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for num in range(num_instances):
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# Filter local hosts based on requirements ...
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hosts = self.host_manager.get_filtered_hosts(hosts,
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spec_obj, index=num)
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if not hosts:
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# Can't get any more locally.
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break
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LOG.debug("Filtered %(hosts)s", {'hosts': hosts})
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weighed_hosts = self.host_manager.get_weighed_hosts(hosts,
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spec_obj)
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LOG.debug("Weighed %(hosts)s", {'hosts': weighed_hosts})
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host_subset_size = max(1, CONF.filter_scheduler.host_subset_size)
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if host_subset_size < len(weighed_hosts):
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weighed_hosts = weighed_hosts[0:host_subset_size]
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chosen_host = random.choice(weighed_hosts)
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LOG.debug("Selected host: %(host)s", {'host': chosen_host})
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selected_hosts.append(chosen_host)
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# Now consume the resources so the filter/weights
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# will change for the next instance.
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chosen_host.obj.consume_from_request(spec_obj)
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if spec_obj.instance_group is not None:
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spec_obj.instance_group.hosts.append(chosen_host.obj.host)
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# hosts has to be not part of the updates when saving
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spec_obj.instance_group.obj_reset_changes(['hosts'])
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return selected_hosts
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def _get_all_host_states(self, context):
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"""Template method, so a subclass can implement caching."""
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return self.host_manager.get_all_host_states(context)
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