Neutron API 流转过程

1、Neutron core server

加载api接口，源码路径：/neutron/service.py

def _run_wsgi(app_name):
    app = config.load_paste_app(app_name)
    if not app:
        LOG.error('No known API applications configured.')
        return
    return run_wsgi_app(app)

load_paste_app代码如下：/neutron/common/config.py

def load_paste_app(app_name):
    """Builds and returns a WSGI app from a paste config file.
    :param app_name: Name of the application to load
    """
    loader = wsgi.Loader(cfg.CONF)
    app = loader.load_app(app_name)
    return app

load_app代码路径：oslo_service/wsgi.py
配置文件路径：/usr/share/neutron/api-paste.ini

[composite:neutron]
use = egg:Paste#urlmap
/: neutronversions_composite
/v2.0: neutronapi_v2_0

[composite:neutronapi_v2_0]
use = call:neutron.auth:pipeline_factory
noauth = cors http_proxy_to_wsgi request_id catch_errors extensions neutronapiapp_v2_0
keystone = cors http_proxy_to_wsgi request_id catch_errors authtoken keystonecontext extensions neutronapiapp_v2_0
[composite:neutron]
use = egg:Paste#urlmap
/: neutronversions_composite
/v2.0: neutronapi_v2_0

[composite:neutronapi_v2_0]
use = call:neutron.auth:pipeline_factory
noauth = cors http_proxy_to_wsgi request_id catch_errors extensions neutronapiapp_v2_0
keystone = cors http_proxy_to_wsgi request_id catch_errors authtoken keystonecontext extensions neutronapiapp_v2_0
省略。。。
[app:neutronversions]
paste.app_factory = neutron.api.versions:Versions.factory

[app:neutronapiapp_v2_0]
paste.app_factory = neutron.api.v2.router:APIRouter.factory

[filter:osprofiler]
paste.filter_factory = osprofiler.web:WsgiMiddleware.factory

Core service 的WSGI Application由：neutron.api.v2.router:APIRouter.factory创建，代码路径：/neutron/api/v2/router.py
这个是关键，这里定义了URL到处理函数的映射关系@@@@

class APIRouter(base_wsgi.Router):

    @classmethod
    def factory(cls, global_config, **local_config):
        if cfg.CONF.web_framework == 'pecan':
            return pecan_app.v2_factory(global_config, **local_config)
        return cls(**local_config)

码路径：/neutron/api/v2/attributes.py
这里定义了资源中字段的取值类型，是否是必须字段等信息。
总结：
资源名字定义：neutron_lib/api/definitions/资源.py （CORE_RESOURCES）
资源属性定义：/neutron/api/v2/attributes.py （RESOURCE_ATTRIBUTE_MAP）
资源对应的处理函数定义：/neutron/api/v2/base.py
把上面两个对象CORE_RESOURCES和RESOURCE_ATTRIBUTE_MAP传入到_map_resource中，构建api与处理函数之间的对应关系，如下：

class APIRouter(base_wsgi.Router):
    def __init__(self, **local_config):
            for resource in RESOURCES:
            _map_resource(RESOURCES[resource], resource,
                          attributes.RESOURCE_ATTRIBUTE_MAP.get(
                              RESOURCES[resource], dict()))
            resource_registry.register_resource_by_name(resource)

/neutron/api/v2/base.py
每个URL对应的处理函数构建

def create_resource(collection, resource, plugin, params, allow_bulk=False,
                    member_actions=None, parent=None, allow_pagination=False,
                    allow_sorting=False):
    controller = Controller(plugin, collection, resource, params, allow_bulk,
                            member_actions=member_actions, parent=parent,
                            allow_pagination=allow_pagination,
                            allow_sorting=allow_sorting)

    return wsgi_resource.Resource(controller, FAULT_MAP)

/neutron/api/v2/resource.py中

result = method(request=request, **args)

2、Neutron extension server

3、agent