vmware-nsx/neutron/scheduler/l3_agent_scheduler.py
Sylvain Afchain 91a7697b1e Add LeastRouters Scheduler to Neutron L3 Agent
Allow scheduling of a virtual router on an L3 Agent node with the least
number of routers currently scheduled. This scheduler can be used
instead of the default random scheduler.

Also refactor the l3_agent_scheduler to allow for adding new schedulers.

Implement blueprint lessrouter-scheduler
Change-Id: Ie539c08bdc8a6e1430a106f77d08f15abd0903e7
2013-12-09 13:25:59 +01:00

193 lines
7.9 KiB
Python

# 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 abc
import random
import six
from sqlalchemy.orm import exc
from sqlalchemy.sql import exists
from neutron.common import constants
from neutron.db import agents_db
from neutron.db import l3_agentschedulers_db
from neutron.db import l3_db
from neutron.openstack.common import log as logging
LOG = logging.getLogger(__name__)
@six.add_metaclass(abc.ABCMeta)
class L3Scheduler(object):
@abc.abstractmethod
def schedule(self, plugin, context, router_id):
"""Schedule the router to an active L3 agent.
Schedule the router only if it is not already scheduled.
"""
pass
def auto_schedule_routers(self, plugin, context, host, router_ids):
"""Schedule non-hosted routers to L3 Agent running on host.
If router_ids is given, each router in router_ids is scheduled
if it is not scheduled yet. Otherwise all unscheduled routers
are scheduled.
Don't schedule the routers which are hosted already
by active l3 agents.
"""
with context.session.begin(subtransactions=True):
# query if we have valid l3 agent on the host
query = context.session.query(agents_db.Agent)
query = query.filter(agents_db.Agent.agent_type ==
constants.AGENT_TYPE_L3,
agents_db.Agent.host == host,
agents_db.Agent.admin_state_up == True)
try:
l3_agent = query.one()
except (exc.MultipleResultsFound, exc.NoResultFound):
LOG.debug(_('No enabled L3 agent on host %s'),
host)
return False
if agents_db.AgentDbMixin.is_agent_down(
l3_agent.heartbeat_timestamp):
LOG.warn(_('L3 agent %s is not active'), l3_agent.id)
# check if each of the specified routers is hosted
if router_ids:
unscheduled_router_ids = []
for router_id in router_ids:
l3_agents = plugin.get_l3_agents_hosting_routers(
context, [router_id], admin_state_up=True)
if l3_agents:
LOG.debug(_('Router %(router_id)s has already been'
' hosted by L3 agent %(agent_id)s'),
{'router_id': router_id,
'agent_id': l3_agents[0]['id']})
else:
unscheduled_router_ids.append(router_id)
if not unscheduled_router_ids:
# all (specified) routers are already scheduled
return False
else:
# get all routers that are not hosted
#TODO(gongysh) consider the disabled agent's router
stmt = ~exists().where(
l3_db.Router.id ==
l3_agentschedulers_db.RouterL3AgentBinding.router_id)
unscheduled_router_ids = [router_id_[0] for router_id_ in
context.session.query(
l3_db.Router.id).filter(stmt)]
if not unscheduled_router_ids:
LOG.debug(_('No non-hosted routers'))
return False
# check if the configuration of l3 agent is compatible
# with the router
routers = plugin.get_routers(
context, filters={'id': unscheduled_router_ids})
to_removed_ids = []
for router in routers:
candidates = plugin.get_l3_agent_candidates(router, [l3_agent])
if not candidates:
to_removed_ids.append(router['id'])
router_ids = set([r['id'] for r in routers]) - set(to_removed_ids)
if not router_ids:
LOG.warn(_('No routers compatible with L3 agent configuration'
' on host %s'), host)
return False
for router_id in router_ids:
self.bind_router(context, router_id, l3_agent)
return True
def get_candidates(self, plugin, context, sync_router):
"""Return L3 agents where a router could be scheduled."""
with context.session.begin(subtransactions=True):
# allow one router is hosted by just
# one enabled l3 agent hosting since active is just a
# timing problem. Non-active l3 agent can return to
# active any time
l3_agents = plugin.get_l3_agents_hosting_routers(
context, [sync_router['id']], admin_state_up=True)
if l3_agents:
LOG.debug(_('Router %(router_id)s has already been hosted'
' by L3 agent %(agent_id)s'),
{'router_id': sync_router['id'],
'agent_id': l3_agents[0]['id']})
return
active_l3_agents = plugin.get_l3_agents(context, active=True)
if not active_l3_agents:
LOG.warn(_('No active L3 agents'))
return
candidates = plugin.get_l3_agent_candidates(sync_router,
active_l3_agents)
if not candidates:
LOG.warn(_('No L3 agents can host the router %s'),
sync_router['id'])
return
return candidates
def bind_router(self, context, router_id, chosen_agent):
"""Bind the router to the l3 agent which has been chosen."""
with context.session.begin(subtransactions=True):
binding = l3_agentschedulers_db.RouterL3AgentBinding()
binding.l3_agent = chosen_agent
binding.router_id = router_id
context.session.add(binding)
LOG.debug(_('Router %(router_id)s is scheduled to '
'L3 agent %(agent_id)s'),
{'router_id': router_id,
'agent_id': chosen_agent.id})
class ChanceScheduler(L3Scheduler):
"""Randomly allocate an L3 agent for a router."""
def schedule(self, plugin, context, router_id):
with context.session.begin(subtransactions=True):
sync_router = plugin.get_router(context, router_id)
candidates = self.get_candidates(plugin, context, sync_router)
if not candidates:
return
chosen_agent = random.choice(candidates)
self.bind_router(context, router_id, chosen_agent)
return chosen_agent
class LeastRoutersScheduler(L3Scheduler):
"""Allocate to an L3 agent with the least number of routers bound."""
def schedule(self, plugin, context, router_id):
with context.session.begin(subtransactions=True):
sync_router = plugin.get_router(context, router_id)
candidates = self.get_candidates(plugin, context, sync_router)
if not candidates:
return
candidate_ids = [candidate['id'] for candidate in candidates]
chosen_agent = plugin.get_l3_agent_with_min_routers(
context, candidate_ids)
self.bind_router(context, router_id, chosen_agent)
return chosen_agent