OpenStack Block Storage (Cinder)
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# Copyright (C) 2014 Hewlett-Packard Development Company, L.P.
# 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 weights
LOG = logging.getLogger(__name__)
class GoodnessWeigher(weights.BaseHostWeigher):
"""Goodness Weigher. Assign weights based on a host's goodness function.
Goodness rating is the following:
.. code-block:: none
0 -- host is a poor choice
50 -- host is a good choice
100 -- host is a perfect choice
def _weigh_object(self, host_state, weight_properties):
"""Determine host's goodness rating based on a goodness_function."""
stats = self._generate_stats(host_state, weight_properties)
LOG.debug("Checking host '%s'", stats['host_stats']['host'])
result = self._check_goodness_function(stats)
LOG.debug("Goodness weight for %(host)s: %(res)s",
{'res': result, 'host': stats['host_stats']['host']})
return result
def _check_goodness_function(self, stats):
"""Gets a host's goodness rating based on its goodness function."""
goodness_rating = 0
if stats['goodness_function'] is None:
LOG.warning("Goodness function not set :: defaulting to "
"minimal goodness rating of 0")
goodness_result = self._run_evaluator(
except Exception as ex:
LOG.warning("Error in goodness_function function "
"'%(function)s' : '%(error)s' :: Defaulting "
"to a goodness of 0",
{'function': stats['goodness_function'],
'error': ex, })
return goodness_rating
if type(goodness_result) is bool:
if goodness_result:
goodness_rating = 100
elif goodness_result < 0 or goodness_result > 100:
LOG.warning("Invalid goodness result. Result must be "
"between 0 and 100. Result generated: '%s' "
":: Defaulting to a goodness of 0",
goodness_rating = goodness_result
return goodness_rating
def _run_evaluator(self, func, stats):
"""Evaluates a given function using the provided available stats."""
host_stats = stats['host_stats']
host_caps = stats['host_caps']
extra_specs = stats['extra_specs']
qos_specs = stats['qos_specs']
volume_stats = stats['volume_stats']
result = evaluator.evaluate(
return result
def _generate_stats(self, host_state, weight_properties):
"""Generates statistics from host and volume data."""
host_stats = {
'volume_backend_name': host_state.volume_backend_name,
'vendor_name': host_state.vendor_name,
'driver_version': host_state.driver_version,
'storage_protocol': host_state.storage_protocol,
'QoS_support': host_state.QoS_support,
'total_capacity_gb': host_state.total_capacity_gb,
'allocated_capacity_gb': host_state.allocated_capacity_gb,
'free_capacity_gb': host_state.free_capacity_gb,
'reserved_percentage': host_state.reserved_percentage,
'updated': host_state.updated,
host_caps = host_state.capabilities
goodness_function = None
if ('goodness_function' in host_caps and
host_caps['goodness_function'] is not None):
goodness_function = str(host_caps['goodness_function'])
qos_specs = weight_properties.get('qos_specs', {}) or {}
volume_type = weight_properties.get('volume_type', {}) or {}
extra_specs = volume_type.get('extra_specs', {})
request_spec = weight_properties.get('request_spec', {}) or {}
volume_stats = request_spec.get('volume_properties', {})
stats = {
'host_stats': host_stats,
'host_caps': host_caps,
'extra_specs': extra_specs,
'qos_specs': qos_specs,
'volume_stats': volume_stats,
'volume_type': volume_type,
'goodness_function': goodness_function,
return stats