Venu & kashyap | added the filter used for cloud bursting

cloud_burst_filter.py

@@ -0,0 +1,46 @@
+# Copyright (c) 2014 ThoughtWorks
+# 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.
+
+from oslo.config import cfg
+from nova import db
+from nova.openstack.common import log as logging
+from nova.scheduler import filters
+
+opts = [
+    cfg.BoolOpt('cloud_burst',
+                help='Switch to enable could bursting'),
+    cfg.StrOpt('cloud_burst_availability_zone',
+                help='The availability zone of only compute hosts with the public cloud driver'),
+]
+CONF = cfg.CONF
+CONF.register_opts(opts)
+
+LOG = logging.getLogger(__name__)
+
+class CloudBurstFilter(filters.BaseHostFilter):
+    """Filter for cloud burst availability zone"""
+
+    run_filter_once_per_request = True
+
+    def host_passes(self, host_state, filter_properties):
+        context = filter_properties['context'].elevated()
+        metadata = db.aggregate_metadata_get_by_host(context, host_state.host, key='availability_zone')
+
+        if CONF.cloud_burst:
+                return CONF.cloud_burst_availability_zone in metadata['availability_zone']
+        else:
+            return CONF.cloud_burst_availability_zone not in metadata['availability_zone']
+
+        return True