neutron openvswitch agent源码分析

1.neutron-openvswitch-agent启动脚本定义在/usr/bin/neutron-openvswitch-agent中，它调用了ovs_neutron_agent中的main()方法。

启动命令:

usr/bin/python2 /usr/bin/neutron-openvswitch-agent --config-file /usr/share/neutron/neutron-dist.conf --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/plugins/ml2/openvswitch_agent.ini --config-dir /etc/neutron/conf.d/common --config-dir /etc/neutron/conf.d/neutron-openvswitch-agent --log-file /var/log/neutron/openvswitch-agent.log

2.该方法又调用了ovs agent中的main()方法。

neutron/cmd/eventlet/plugins/ovs_neutron_agent.py
def main():
    agent_main.main()

3.根据of_interface的配置，包含ovs-ofctl和native两种方式，执行具体的启动流程。

neutron/plugins/ml2/drivers/openvswitch/agent/main.py

def main():

    common_config.init(sys.argv[1:])

    driver_name = cfg.CONF.OVS.of_interface

    mod_name = _main_modules[driver_name]

    mod = importutils.import_module(mod_name)

    mod.init_config()

    common_config.setup_logging()

    profiler.setup("neutron-ovs-agent", cfg.CONF.host)

    mod.main()

4.根据neutron.conf中的默认配置，执行native中的mian()方法。

neutron/plugins/ml2/drivers/openvswitch/agent/openflow/native/main.py

def main():

    app_manager.AppManager.run_apps([

        'neutron.plugins.ml2.drivers.openvswitch.agent.'

        'openflow.native.ovs_ryuapp',

    ])

5.通过Ryu启动OVS应用，调用ovs agent的main()方法。

neutron/plugins/ml2/drivers/openvswitch/agent/openflow/native/ovs_ryuapp.py

def agent_main_wrapper(bridge_classes):

    try:

        ovs_agent.main(bridge_classes)

    except Exception:

        with excutils.save_and_reraise_exception():

            LOG.exception("Agent main thread died of an exception")

    finally:

        # The following call terminates Ryu's AppManager.run_apps(),

        # which is needed for clean shutdown of an agent process.

        # The close() call must be called in another thread, otherwise

        # it suicides and ends prematurely.

        hub.spawn(app_manager.AppManager.get_instance().close)



class OVSNeutronAgentRyuApp(app_manager.RyuApp):

    OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]



    def start(self):

        # Start Ryu event loop thread

        super(OVSNeutronAgentRyuApp, self).start()



        def _make_br_cls(br_cls):

            return functools.partial(br_cls, ryu_app=self)



        # Start agent main loop thread

        bridge_classes = {

            'br_int': _make_br_cls(br_int.OVSIntegrationBridge),

            'br_phys': _make_br_cls(br_phys.OVSPhysicalBridge),

            'br_tun': _make_br_cls(br_tun.OVSTunnelBridge),

        }

        return hub.spawn(agent_main_wrapper, bridge_classes, raise_error=True)

6.加载配置文件、插件，校验配置项，创建ovs agent实例，daemon_loop()方法定时更新端口信息。

neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py

def main(bridge_classes):

    prepare_xen_compute()

    ovs_capabilities.register()

    ext_manager.register_opts(cfg.CONF)



    ext_mgr = ext_manager.L2AgentExtensionsManager(cfg.CONF)



    # now that all extensions registered their options, we can log them

    n_utils.log_opt_values(LOG)



    validate_tunnel_config(cfg.CONF.AGENT.tunnel_types, cfg.CONF.OVS.local_ip)



    try:

        agent = OVSNeutronAgent(bridge_classes, ext_mgr, cfg.CONF)

        capabilities.notify_init_event(n_const.AGENT_TYPE_OVS, agent)

    except (RuntimeError, ValueError) as e:

        LOG.error("%s Agent terminated!", e)

        sys.exit(1)

    agent.daemon_loop()

OVSNeutronAgent的初始化方法中主要创建br-int、br-tun以及vlan和flat网络模式下与物理网络相关联的br-phys网桥，启动rpc服务，创建定时任务，定时向neutron server更新ovs agent的状态。

def setup_integration_br(self):

        '''Setup the integration bridge.



        '''

        # Ensure the integration bridge is created.

        # ovs_lib.OVSBridge.create() will run

        #   ovs-vsctl -- --may-exist add-br BRIDGE_NAME

        # which does nothing if bridge already exists.

        self.int_br.create()

        self.int_br.set_secure_mode()

        self.int_br.setup_controllers(self.conf)



        if self.conf.AGENT.drop_flows_on_start:

            # Delete the patch port between br-int and b