Add agent scheduling for LBaaS namespace agent

- adds simple chance scheduling on create pool operation - adds PoolsLoadbalancerAgentBinding db table - adds lbaas_agentscheduler extension to list pools hosted by a particular agent and to get an agent hosting a particular pool - adds agent notifiers mapping to AgentSchedulerDbMixin to make it easier for services to add their agent notifiers to the core plugin Implements blueprint lbaas-agent-scheduler Change-Id: Id98649fd5c7873dcd5be1a2b117b8bed25f06cc2
2013-05-29 11:58:17 +04:00
parent 040c4e0b8b
commit 37581d55ab
9 changed files with 623 additions and 108 deletions
--- a/neutron/services/loadbalancer/agent_scheduler.py
+++ b/neutron/services/loadbalancer/agent_scheduler.py
@@ -0,0 +1,114 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright (c) 2013 OpenStack Foundation.
+# 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.
+
+import random
+
+import sqlalchemy as sa
+from sqlalchemy import orm
+from sqlalchemy.orm import joinedload
+
+from neutron.common import constants
+from neutron.db import agents_db
+from neutron.db import agentschedulers_db
+from neutron.db import model_base
+from neutron.extensions import lbaas_agentscheduler
+from neutron.openstack.common import log as logging
+
+LOG = logging.getLogger(__name__)
+
+
+class PoolLoadbalancerAgentBinding(model_base.BASEV2):
+    """Represents binding between neutron loadbalancer pools and agents."""
+
+    pool_id = sa.Column(sa.String(36),
+                        sa.ForeignKey("pools.id", ondelete='CASCADE'),
+                        primary_key=True)
+    agent = orm.relation(agents_db.Agent)
+    agent_id = sa.Column(sa.String(36), sa.ForeignKey("agents.id",
+                                                      ondelete='CASCADE'))
+
+
+class LbaasAgentSchedulerDbMixin(agentschedulers_db.AgentSchedulerDbMixin,
+                                 lbaas_agentscheduler
+                                 .LbaasAgentSchedulerPluginBase):
+
+    def get_lbaas_agent_hosting_pool(self, context, pool_id, active=None):
+        query = context.session.query(PoolLoadbalancerAgentBinding)
+        query = query.options(joinedload('agent'))
+        binding = query.get(pool_id)
+
+        if (binding and self.is_eligible_agent(
+                active, binding.agent)):
+            return {'agent': self._make_agent_dict(binding.agent)}
+
+    def get_lbaas_agents(self, context, active=None, filters=None):
+        query = context.session.query(agents_db.Agent)
+        query = query.filter_by(agent_type=constants.AGENT_TYPE_LOADBALANCER)
+        if active is not None:
+            query = query.filter_by(admin_state_up=active)
+        if filters:
+            for key, value in filters.iteritems():
+                column = getattr(agents_db.Agent, key, None)
+                if column:
+                    query = query.filter(column.in_(value))
+
+        return [agent
+                for agent in query
+                if self.is_eligible_agent(active, agent)]
+
+    def list_pools_on_lbaas_agent(self, context, id):
+        query = context.session.query(PoolLoadbalancerAgentBinding.pool_id)
+        query = query.filter_by(agent_id=id)
+        pool_ids = [item[0] for item in query]
+        if pool_ids:
+            return {'pools': self.get_pools(context, filters={'id': pool_ids})}
+        else:
+            return {'pools': []}
+
+
+class ChanceScheduler(object):
+    """Allocate a loadbalancer agent for a vip in a random way."""
+
+    def schedule(self, plugin, context, pool):
+        """Schedule the pool to an active loadbalancer agent if there
+        is no enabled agent hosting it.
+        """
+        with context.session.begin(subtransactions=True):
+            lbaas_agent = plugin.get_lbaas_agent_hosting_pool(
+                context, pool['id'])
+            if lbaas_agent:
+                LOG.debug(_('Pool %(pool_id)s has already been hosted'
+                            ' by lbaas agent %(agent_id)s'),
+                          {'pool_id': pool['id'],
+                           'agent_id': lbaas_agent['id']})
+                return
+
+            candidates = plugin.get_lbaas_agents(context, active=True)
+            if not candidates:
+                LOG.warn(_('No active lbaas agents for pool %s') % pool['id'])
+                return
+
+            chosen_agent = random.choice(candidates)
+            binding = PoolLoadbalancerAgentBinding()
+            binding.agent = chosen_agent
+            binding.pool_id = pool['id']
+            context.session.add(binding)
+            LOG.debug(_('Pool %(pool_id)s is scheduled to '
+                        'lbaas agent %(agent_id)s'),
+                      {'pool_id': pool['id'],
+                       'agent_id': chosen_agent['id']})
+            return chosen_agent