208 lines
7.9 KiB
Python
208 lines
7.9 KiB
Python
# Copyright (c) 2012 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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"""Availability zone helper functions."""
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import collections
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import six
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from nova import cache_utils
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import nova.conf
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from nova import objects
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# NOTE(vish): azs don't change that often, so cache them for an hour to
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# avoid hitting the db multiple times on every request.
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AZ_CACHE_SECONDS = 60 * 60
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MC = None
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CONF = nova.conf.CONF
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def _get_cache():
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global MC
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if MC is None:
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MC = cache_utils.get_client(expiration_time=AZ_CACHE_SECONDS)
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return MC
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def reset_cache():
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"""Reset the cache, mainly for testing purposes and update
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availability_zone for host aggregate
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"""
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global MC
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MC = None
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def _make_cache_key(host):
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if six.PY2:
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host = host.encode('utf-8')
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return "azcache-%s" % host
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def _build_metadata_by_host(aggregates, hosts=None):
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if hosts and not isinstance(hosts, set):
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hosts = set(hosts)
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metadata = collections.defaultdict(set)
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for aggregate in aggregates:
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for host in aggregate.hosts:
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if hosts and host not in hosts:
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continue
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metadata[host].add(list(aggregate.metadata.values())[0])
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return metadata
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def set_availability_zones(context, services):
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# Makes sure services isn't a sqlalchemy object
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services = [dict(service) for service in services]
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hosts = set([service['host'] for service in services])
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aggregates = objects.AggregateList.get_by_metadata_key(context,
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'availability_zone', hosts=hosts)
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metadata = _build_metadata_by_host(aggregates, hosts=hosts)
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# gather all of the availability zones associated with a service host
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for service in services:
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az = CONF.internal_service_availability_zone
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if service['topic'] == "compute":
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if metadata.get(service['host']):
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az = u','.join(list(metadata[service['host']]))
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else:
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az = CONF.default_availability_zone
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# update the cache
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update_host_availability_zone_cache(context,
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service['host'], az)
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service['availability_zone'] = az
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return services
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def get_host_availability_zone(context, host):
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aggregates = objects.AggregateList.get_by_host(context, host,
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key='availability_zone')
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if aggregates:
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az = aggregates[0].metadata['availability_zone']
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else:
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az = CONF.default_availability_zone
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return az
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def update_host_availability_zone_cache(context, host, availability_zone=None):
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if not availability_zone:
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availability_zone = get_host_availability_zone(context, host)
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cache = _get_cache()
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cache_key = _make_cache_key(host)
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cache.delete(cache_key)
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cache.set(cache_key, availability_zone)
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def get_availability_zones(context, get_only_available=False,
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with_hosts=False, enabled_services=None,
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hostapi=None):
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"""Return available and unavailable zones on demand.
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:param get_only_available: flag to determine whether to return
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available zones only, default False indicates return both
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available zones and not available zones, True indicates return
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available zones only
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:param with_hosts: whether to return hosts part of the AZs
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:type with_hosts: bool
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:param enabled_services: list of enabled services to use; if None
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enabled services will be retrieved from all cells with zones set
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:param hostapi: nova.compute.api.HostAPI instance
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"""
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# TODO(mriedem): Make hostapi a required arg in a non-backportable FUP.
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if hostapi is None:
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# NOTE(danms): Avoid circular import
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from nova import compute
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hostapi = compute.HostAPI()
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if enabled_services is None:
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enabled_services = hostapi.service_get_all(
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context, {'disabled': False}, set_zones=True, all_cells=True)
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available_zones = []
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for (zone, host) in [(service['availability_zone'], service['host'])
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for service in enabled_services]:
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if not with_hosts and zone not in available_zones:
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available_zones.append(zone)
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elif with_hosts:
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_available_zones = dict(available_zones)
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zone_hosts = _available_zones.setdefault(zone, set())
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zone_hosts.add(host)
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# .items() returns a view in Py3, casting it to list for Py2 compat
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available_zones = list(_available_zones.items())
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if not get_only_available:
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# TODO(mriedem): We could probably optimize if we know that we're going
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# to get both enabled and disabled services and just pull them all from
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# the cell DBs at the same time and then filter into enabled/disabled
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# lists in python.
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disabled_services = hostapi.service_get_all(
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context, {'disabled': True}, set_zones=True, all_cells=True)
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not_available_zones = []
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azs = available_zones if not with_hosts else dict(available_zones)
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zones = [(service['availability_zone'], service['host'])
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for service in disabled_services
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if service['availability_zone'] not in azs]
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for (zone, host) in zones:
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if not with_hosts and zone not in not_available_zones:
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not_available_zones.append(zone)
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elif with_hosts:
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_not_available_zones = dict(not_available_zones)
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zone_hosts = _not_available_zones.setdefault(zone, set())
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zone_hosts.add(host)
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# .items() returns a view in Py3, casting it to list for Py2
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# compat
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not_available_zones = list(_not_available_zones.items())
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return (available_zones, not_available_zones)
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else:
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return available_zones
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def get_instance_availability_zone(context, instance):
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"""Return availability zone of specified instance."""
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host = instance.host if 'host' in instance else None
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if not host:
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# Likely hasn't reached a viable compute node yet so give back the
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# desired availability_zone in the instance record if the boot request
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# specified one.
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az = instance.get('availability_zone')
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return az
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cache_key = _make_cache_key(host)
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cache = _get_cache()
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az = cache.get(cache_key)
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az_inst = instance.get('availability_zone')
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if az_inst is not None and az != az_inst:
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# NOTE(sbauza): Cache is wrong, we need to invalidate it by fetching
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# again the right AZ related to the aggregate the host belongs to.
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# As the API is also calling this method for setting the instance
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# AZ field, we don't need to update the instance.az field.
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# This case can happen because the cache is populated before the
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# instance has been assigned to the host so that it would keep the
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# former reference which was incorrect. Instead of just taking the
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# instance AZ information for refilling the cache, we prefer to
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# invalidate the cache and fetch it again because there could be some
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# corner cases where this method could be called before the instance
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# has been assigned to the host also.
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az = None
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if not az:
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elevated = context.elevated()
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az = get_host_availability_zone(elevated, host)
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cache.set(cache_key, az)
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return az
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