64 lines
2.3 KiB
Python
64 lines
2.3 KiB
Python
# Copyright (c) 2011 Openstack, LLC.
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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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"""
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The Host Filter classes are a way to ensure that only hosts that are
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appropriate are considered when creating a new instance. Hosts that are
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either incompatible or insufficient to accept a newly-requested instance
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are removed by Host Filter classes from consideration. Those that pass
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the filter are then passed on for weighting or other process for ordering.
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Filters are in the 'filters' directory that is off the 'scheduler'
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directory of nova. Additional filters can be created and added to that
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directory; be sure to add them to the filters/__init__.py file so that
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they are part of the nova.schedulers.filters namespace.
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"""
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import types
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from nova import exception
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from nova import flags
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import nova.scheduler
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FLAGS = flags.FLAGS
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def _get_filters():
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# Imported here to avoid circular imports
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from nova.scheduler import filters
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def get_itm(nm):
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return getattr(filters, nm)
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return [get_itm(itm) for itm in dir(filters)
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if (type(get_itm(itm)) is types.TypeType)
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and issubclass(get_itm(itm), filters.AbstractHostFilter)
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and get_itm(itm) is not filters.AbstractHostFilter]
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def choose_host_filter(filter_name=None):
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"""Since the caller may specify which filter to use we need
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to have an authoritative list of what is permissible. This
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function checks the filter name against a predefined set
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of acceptable filters.
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"""
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if not filter_name:
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filter_name = FLAGS.default_host_filter
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for filter_class in _get_filters():
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if filter_class.__name__ == filter_name:
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return filter_class()
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raise exception.SchedulerHostFilterNotFound(filter_name=filter_name)
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