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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright (c) 2010 OpenStack Foundation
# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Chance (Random) Scheduler implementation
"""
import random
from oslo.config import cfg
from nova.compute import rpcapi as compute_rpcapi
from nova import exception
from nova.scheduler import driver
CONF = cfg.CONF
CONF.import_opt('compute_topic', 'nova.compute.rpcapi')
class ChanceScheduler(driver.Scheduler):
"""Implements Scheduler as a random node selector."""
def __init__(self, *args, **kwargs):
super(ChanceScheduler, self).__init__(*args, **kwargs)
self.compute_rpcapi = compute_rpcapi.ComputeAPI()
def _filter_hosts(self, request_spec, hosts, filter_properties):
"""Filter a list of hosts based on request_spec."""
ignore_hosts = filter_properties.get('ignore_hosts', [])
hosts = [host for host in hosts if host not in ignore_hosts]
return hosts
def _schedule(self, context, topic, request_spec, filter_properties):
"""Picks a host that is up at random."""
elevated = context.elevated()
hosts = self.hosts_up(elevated, topic)
if not hosts:
msg = _("Is the appropriate service running?")
raise exception.NoValidHost(reason=msg)
hosts = self._filter_hosts(request_spec, hosts, filter_properties)
if not hosts:
msg = _("Could not find another compute")
raise exception.NoValidHost(reason=msg)
return random.choice(hosts)
def select_hosts(self, context, request_spec, filter_properties):
"""Selects a set of random hosts."""
hosts = [self._schedule(context, CONF.compute_topic,
request_spec, filter_properties)
for instance_uuid in request_spec.get('instance_uuids', [])]
if not hosts:
raise exception.NoValidHost(reason="")
return hosts
def select_destinations(self, context, request_spec, filter_properties):
"""Selects random destinations."""
num_instances = request_spec['num_instances']
# NOTE(alaski): Returns a list of tuples for compatibility with
# filter_scheduler
dests = [(self._schedule(context, CONF.compute_topic, request_spec,
filter_properties), None) for i in range(num_instances)]
if len(dests) < num_instances:
raise exception.NoValidHost(reason='')
return dests
def schedule_run_instance(self, context, request_spec,
admin_password, injected_files,
requested_networks, is_first_time,
filter_properties):
"""Create and run an instance or instances."""
instance_uuids = request_spec.get('instance_uuids')
for num, instance_uuid in enumerate(instance_uuids):
request_spec['instance_properties']['launch_index'] = num
try:
host = self._schedule(context, CONF.compute_topic,
request_spec, filter_properties)
updated_instance = driver.instance_update_db(context,
instance_uuid)
self.compute_rpcapi.run_instance(context,
instance=updated_instance, host=host,
requested_networks=requested_networks,
injected_files=injected_files,
admin_password=admin_password,
is_first_time=is_first_time,
request_spec=request_spec,
filter_properties=filter_properties)
except Exception as ex:
# NOTE(vish): we don't reraise the exception here to make sure
# that all instances in the request get set to
# error properly
driver.handle_schedule_error(context, ex, instance_uuid,
request_spec)
def schedule_prep_resize(self, context, image, request_spec,
filter_properties, instance, instance_type,
reservations):
"""Select a target for resize."""
host = self._schedule(context, CONF.compute_topic, request_spec,
filter_properties)
self.compute_rpcapi.prep_resize(context, image, instance,
instance_type, host, reservations)
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