1# Copyright (c) 2011-2012 OpenStack Foundation.
2# All Rights Reserved.
3#
4#    Licensed under the Apache License, Version 2.0 (the "License"); you may
5#    not use this file except in compliance with the License. You may obtain
6#    a copy of the License at
7#
8#         http://www.apache.org/licenses/LICENSE-2.0
9#
10#    Unless required by applicable law or agreed to in writing, software
11#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13#    License for the specific language governing permissions and limitations
14#    under the License.
15
16from cinder.scheduler import filters
17
18
19class AvailabilityZoneFilter(filters.BaseBackendFilter):
20    """Filters Backends by availability zone."""
21
22    # Availability zones do not change within a request
23    run_filter_once_per_request = True
24
25    def backend_passes(self, backend_state, filter_properties):
26        spec = filter_properties.get('request_spec', {})
27        props = spec.get('resource_properties', {})
28        availability_zone = props.get('availability_zone')
29
30        if availability_zone:
31            return (availability_zone ==
32                    backend_state.service['availability_zone'])
33        return True
34