nova/nova/scheduler/filters/isolated_hosts_filter.py
Dan Smith f7c688b8ef Refined fix for validating image on rebuild
This aims to fix the issue described in bug 1664931 where a rebuild
fails to validate the existing host with the scheduler when a new
image is provided. The previous attempt to do this could cause rebuilds
to fail unnecessarily because we ran _all_ of the filters during a
rebuild, which could cause usage/resource filters to prevent an otherwise
valid rebuild from succeeding.

This aims to classify filters as useful for rebuild or not, and only apply
the former during a rebuild scheduler check. We do this by using an internal
scheduler hint, indicating our intent. This should (a) filter out
all hosts other than the one we're running on and (b) be detectable by
the filtering infrastructure as an internally-generated scheduling request
in order to trigger the correct filtering behavior.

Closes-Bug: #1664931
Change-Id: I1a46ef1503be2febcd20f4594f44344d05525446
2017-11-27 15:52:45 -05:00

70 lines
2.8 KiB
Python

# Copyright (c) 2011-2012 OpenStack Foundation
# 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.
import nova.conf
from nova.scheduler import filters
CONF = nova.conf.CONF
class IsolatedHostsFilter(filters.BaseHostFilter):
"""Keep specified images to selected hosts."""
# The configuration values do not change within a request
run_filter_once_per_request = True
RUN_ON_REBUILD = True
def host_passes(self, host_state, spec_obj):
"""Result Matrix with 'restrict_isolated_hosts_to_isolated_images' set
to True::
| | isolated_image | non_isolated_image
| -------------+----------------+-------------------
| iso_host | True | False
| non_iso_host | False | True
Result Matrix with 'restrict_isolated_hosts_to_isolated_images' set
to False::
| | isolated_image | non_isolated_image
| -------------+----------------+-------------------
| iso_host | True | True
| non_iso_host | False | True
"""
# If the configuration does not list any hosts, the filter will always
# return True, assuming a configuration error, so letting all hosts
# through.
isolated_hosts = CONF.filter_scheduler.isolated_hosts
isolated_images = CONF.filter_scheduler.isolated_images
restrict_isolated_hosts_to_isolated_images = (
CONF.filter_scheduler.restrict_isolated_hosts_to_isolated_images)
if not isolated_images:
# As there are no images to match, return True if the filter is
# not restrictive otherwise return False if the host is in the
# isolation list.
return ((not restrict_isolated_hosts_to_isolated_images) or
(host_state.host not in isolated_hosts))
image_ref = spec_obj.image.id if spec_obj.image else None
image_isolated = image_ref in isolated_images
host_isolated = host_state.host in isolated_hosts
if restrict_isolated_hosts_to_isolated_images:
return (image_isolated == host_isolated)
else:
return (not image_isolated) or host_isolated