NeutronL3Agent之PrefixDelegation.md

Neutron L3 Agent 之 PrefixDelegation

neutron/agent/linux/pd.py

class PrefixDelegation(object)

    def __init__(self, context, pmon, intf_driver, notifier, pd_update_cb,
                 agent_conf):
        self.context = context
        self.pmon = pmon
        self.intf_driver = intf_driver
        self.notifier = notifier
        self.routers = {}
        self.pd_update_cb = pd_update_cb
        self.agent_conf = agent_conf
        self.pd_dhcp_driver = driver.DriverManager(
            namespace='neutron.agent.linux.pd_drivers',
            name=agent_conf.prefix_delegation_driver,
        ).driver
        registry.subscribe(add_router,
                           resources.ROUTER,
                           events.BEFORE_CREATE)
        registry.subscribe(remove_router,
                           resources.ROUTER,
                           events.AFTER_DELETE)
        self._get_sync_data()

1. 初始化一些属性
2. 加载 prefix_delegation_driver 驱动，默认为 dibbler（这里只是加载了，并没有实例化）
3. 通过回调系统注册感谢去资源
4. resourece : ROUTER ; event : BEFORE_CREATE ; callback : add_router
5. resourece : ROUTER ; event : AFTER_CREATE ; callback : remove_router
6. 调用 _get_sync_data 方法

neutron.agent.linux.pd_drivers =
    dibbler = neutron.agent.linux.dibbler:PDDibbler

def _get_sync_data(self)

我们暂时还未用到这里的功能，所以以后再进行分析

1. 调用 pd_dhcp_driver.get_sync_data 方法

def after_start(self)

l3 agent 启动后会调用

    def after_start(self):
        LOG.debug('SIGUSR1 signal handler set')
        signal.signal(signal.SIGUSR1, self._handle_sigusr1)

设定 _handle_sigusr1 来处理信号

def _handle_sigusr1(self, signum, frame)

    def _handle_sigusr1(self, signum, frame):
        """Update PD on receiving SIGUSR1.

        The external DHCPv6 client uses SIGUSR1 to notify agent
        of prefix changes.
        """
        self.pd_update_cb()

这个 pd_update_cb 就是在初始化时由 L3NATAgentWithStateReport 传递过来的 plugin_rpc.process_prefix_update 方法。