openstack neutron网络模块分析（二）--- APIRouter

最新推荐文章于 2025-07-05 16:43:06 发布

energysober

最新推荐文章于 2025-07-05 16:43:06 发布

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分类专栏： openstack neutron 文章标签： openstack neutron APIRouter分析

本文链接：https://blog.youkuaiyun.com/energysober/article/details/80390568

本文深入分析OpenStack Neutron的APIRouter，讲解其如何将HTTP请求路由到对应控制器，以及核心插件和服务插件的加载过程。涉及APIRouter的Mapper构造、service_plugins和服务插件的加载、extension的加载和映射，以及启动时的plugin与extension创建顺序。文章还提到了配置文件和相关源码分析。

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neutron APIRouter分析

环境:ocata版本，centos7
这篇文章主要分析的几个点：
一、 APIRouter究竟是如何将client端发来的http请求路由到指定的资源controller
二、 Plugin和extension的创建过程

APIRouter

代码目录：/neutron/api/v2/router.py

class APIRouter(base_wsgi.Router):

	@classmethod
	def factory(cls, global_config, **local_config):
	    return cls(**local_config)

这里是以工厂方法去构造一个APIRouter对象

 def __init__(self, **local_config):
        mapper = routes_mapper.Mapper()
        manager.init()
        plugin = directory.get_plugin()
        ext_mgr = extensions.PluginAwareExtensionManager.get_instance()
        ext_mgr.extend_resources("2.0", attributes.RESOURCE_ATTRIBUTE_MAP)

        col_kwargs = dict(collection_actions=COLLECTION_ACTIONS,
                          member_actions=MEMBER_ACTIONS)

        def _map_resource(collection, resource, params, parent=None):
            allow_bulk = cfg.CONF.allow_bulk
            controller = base.create_resource(
                collection, resource, plugin, params, allow_bulk=allow_bulk,
                parent=parent, allow_pagination=True,
                allow_sorting=True)
            path_prefix = None
            if parent:
                path_prefix = "/%s/{%s_id}/%s" % (parent['collection_name'],
                                                  parent['member_name'],
                                                  collection)
            mapper_kwargs = dict(controller=controller,
                                 requirements=REQUIREMENTS,
                                 path_prefix=path_prefix,
                                 **col_kwargs)
            return mapper.collection(collection, resource,
                                     **mapper_kwargs)

        mapper.connect('index', '/', controller=Index(RESOURCES))
        for resource in RESOURCES:
            _map_resource(RESOURCES[resource], resource,
                          attributes.RESOURCE_ATTRIBUTE_MAP.get(
                              RESOURCES[resource], dict()))
            resource_registry.register_resource_by_name(resource)

        for resource in SUB_RESOURCES:
            _map_resource(SUB_RESOURCES[resource]['collection_name'], resource,
                          attributes.RESOURCE_ATTRIBUTE_MAP.get(
                              SUB_RESOURCES[resource]['collection_name'],
                              dict()),
                          SUB_RESOURCES[resource]['parent'])

        # Certain policy checks require that the extensions are loaded
        # and the RESOURCE_ATTRIBUTE_MAP populated before they can be
        # properly initialized. This can only be claimed with certainty
        # once this point in the code has been reached. In the event
        # that the policies have been initialized before this point,
        # calling reset will cause the next policy check to
        # re-initialize with all of the required data in place.
        policy.reset()
        super(APIRouter, self).__init__(mapper)

上面的就是 APIRouter的核心代码了，下面详细分析：
**先看 **

mapper = routes_mapper.Mapper()

先声明一个routes Mapper，（Mapper的代码能从安装openstack的环境下的/usr/lib/python2.7/site-packages/routes下），

 def connect(self, *args, **kargs):
        """Create and connect a new Route to the Mapper.
        
        Usage:
        
        .. code-block:: python
        
            m = Mapper()
            m.connect(':controller/:action/:id')
            m.connect('date/:year/:month/:day', controller="blog", action="view")
            m.connect('archives/:page', controller="blog", action="by_page",
            requirements = { 'page':'\d{1,2}' })
            m.connect(