OpenStack Block Storage (Cinder)
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# Copyright (c) 2014 Hewlett-Packard Development Company, L.P.
# 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
# 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.
from oslo_log import log as logging
from cinder.scheduler.evaluator import evaluator
from cinder.scheduler import filters
LOG = logging.getLogger(__name__)
class DriverFilter(filters.BaseBackendFilter):
"""DriverFilter filters backend based on a 'filter function' and metrics.
DriverFilter filters based on volume backend's provided 'filter function'
and metrics.
def backend_passes(self, backend_state, filter_properties):
"""Determines if a backend has a passing filter_function or not."""
stats = self._generate_stats(backend_state, filter_properties)
LOG.debug("Checking backend '%s'",
result = self._check_filter_function(stats)
LOG.debug("Result: %s", result)
LOG.debug("Done checking backend '%s'",
return result
def _check_filter_function(self, stats):
"""Checks if a volume passes a backend's filter function.
Returns a tuple in the format (filter_passing, filter_invalid).
Both values are booleans.
if stats['filter_function'] is None:
LOG.debug("Filter function not set :: passing backend")
return True
filter_result = self._run_evaluator(stats['filter_function'],
except Exception as ex:
# Warn the admin for now that there is an error in the
# filter function.
LOG.warning("Error in filtering function "
"'%(function)s' : '%(error)s' :: failing backend",
{'function': stats['filter_function'],
'error': ex, })
return False
return filter_result
def _run_evaluator(self, func, stats):
"""Evaluates a given function using the provided available stats."""
backend_stats = stats['backend_stats']
backend_caps = stats['backend_caps']
extra_specs = stats['extra_specs']
qos_specs = stats['qos_specs']
volume_stats = stats['volume_stats']
LOG.debug('Running evaluator: extra_specs: %(extra)s\n'
'stats: %(stats)s\n'
'capabilities: %(capabilities)s\n'
'volume: %(volume)s\n'
'qos: %(qos)s', {'extra': extra_specs,
'stats': backend_stats,
'capabilities': backend_caps,
'volume': volume_stats,
'qos': qos_specs})
result = evaluator.evaluate(
return result
def _generate_stats(self, backend_state, filter_properties):
"""Generates statistics from backend and volume data."""
backend_stats = {
'cluster_name': backend_state.cluster_name,
'backend_id': backend_state.backend_id,
'volume_backend_name': backend_state.volume_backend_name,
'vendor_name': backend_state.vendor_name,
'driver_version': backend_state.driver_version,
'storage_protocol': backend_state.storage_protocol,
'QoS_support': backend_state.QoS_support,
'total_capacity_gb': backend_state.total_capacity_gb,
'allocated_capacity_gb': backend_state.allocated_capacity_gb,
'free_capacity_gb': backend_state.free_capacity_gb,
'reserved_percentage': backend_state.reserved_percentage,
'updated': backend_state.updated,
backend_caps = backend_state.capabilities
filter_function = None
if ('filter_function' in backend_caps and
backend_caps['filter_function'] is not None):
filter_function = str(backend_caps['filter_function'])
qos_specs = filter_properties.get('qos_specs', {})
volume_type = filter_properties.get('volume_type', {})
extra_specs = volume_type.get('extra_specs', {})
request_spec = filter_properties.get('request_spec', {})
volume_stats = request_spec.get('volume_properties', {})
stats = {
'backend_stats': backend_stats,
'backend_caps': backend_caps,
'extra_specs': extra_specs,
'qos_specs': qos_specs,
'volume_stats': volume_stats,
'volume_type': volume_type,
'filter_function': filter_function,
return stats