Weigh nodes by their ports quantity

The default is to preferably choose nodes with less ports.
If you prefer choosing more ports nodes, you can set the
'port_weight_multiplier' option to a positive number and
the weighing has the opposite effect of the default.

Change-Id: Ic936301a83658ebba5fb9a689505acb5a090aa71

mogan/conf/scheduler.py

@@ -41,7 +41,9 @@ opts = [
                 help=_('Which filter class names to use for filtering nodes '
                        'when not specified in the request.')),
     cfg.ListOpt('scheduler_default_weighers',
-                default=[],
+                default=[
+                    'PortWeigher',
+                ],
                 help=_('Which weigher class names to use for weighing '
                        'nodes.')),
     cfg.StrOpt('scheduler_weight_handler',
@@ -49,6 +51,9 @@ opts = [
                        'OrderedNodeWeightHandler',
                help=_('Which handler to use for selecting the node after '
                       'weighing')),
+    cfg.FloatOpt('port_weight_multiplier',
+                 default=-1.0,
+                 help=_('Node ports quantity weight multipler ratio.')),
 ]
 
 

mogan/engine/scheduler/weights/port.py

@@ -0,0 +1,41 @@
+# Copyright 2017 Huawei Technologies Co.,LTD.
+# 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
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    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.
+"""
+Port Weigher.  Weigh nodes by their ports quantity.
+
+The default is to preferably choose nodes with less ports. If you prefer
+choosing more ports nodes, you can set the 'port_weight_multiplier' option
+to a positive number and the weighing has the opposite effect of the default.
+"""
+
+from oslo_config import cfg
+
+from mogan.engine.scheduler import weights
+
+CONF = cfg.CONF
+
+
+class PortWeigher(weights.BaseNodeWeigher):
+    minval = 0
+
+    def weight_multiplier(self):
+        """Override the weight multiplier."""
+        return CONF.scheduler.port_weight_multiplier
+
+    def _weigh_object(self, node_state, weight_properties):
+        """Higher weights win. We want to choose less ports node to be the
+        default.
+        """
+        return len(node_state.ports)

setup.cfg

@@ -31,6 +31,8 @@ mogan.engine.scheduler.filters =
     CapabilitiesFilter = mogan.engine.scheduler.filters.capabilities_filter:CapabilitiesFilter
     PortsFilter = mogan.engine.scheduler.filters.ports_filter:PortsFilter
     JsonFilter = mogan.engine.scheduler.filters.json_filter:JsonFilter
+mogan.engine.scheduler.weights =
+    PortWeigher = mogan.engine.scheduler.weights.port:PortWeigher
 
 oslo.config.opts =
     mogan = mogan.conf.opts:list_opts