OpenStack Study: availability_zone_filter.py

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# 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

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# http://www.apache.org/licenses/LICENSE-2.0

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# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT

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from oslo.config import cfg

from nova import db

from nova.scheduler import filters

CONF = cfg.CONF

CONF.import_opt('default_availability_zone', 'nova.availability_zones')

**** CubicPower OpenStack Study ****

class AvailabilityZoneFilter(filters.BaseHostFilter):

"""Filters Hosts by availability zone.

Works with aggregate metadata availability zones, using the key

'availability_zone'

Note: in theory a compute node can be part of multiple availability_zones

"""

# Availability zones do not change within a request

run_filter_once_per_request = True

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    def host_passes(self, host_state, filter_properties):

        spec = filter_properties.get('request_spec', {})

        props = spec.get('instance_properties', {})

        availability_zone = props.get('availability_zone')

        if availability_zone:

            context = filter_properties['context'].elevated()

            metadata = db.aggregate_metadata_get_by_host(

                         context, host_state.host, key='availability_zone')

            if 'availability_zone' in metadata:

                return availability_zone in metadata['availability_zone']

            else:

                return availability_zone == CONF.default_availability_zone

        return True