Neutron分析（2）——neutron-server启动过程分析

neutron-server启动过程分析

1. /etc/init.d/neutron-server

DAEMON=/usr/bin/neutron-server
DAEMON_ARGS="--log-file=$LOGFILE"
DAEMON_DIR=/var/run
...
case $1 in
start)
test "$ENABLED" = "true" || exit 0
log_daemon_msg "Starting neutron server" "neutron-server"
start-stop-daemon -Sbmv --pidfile $PIDFILE --chdir $DAEMON_DIR --exec $DAEMON -- $DAEMON_ARGS
log_end_msg $?
;;
...
esac

2. /usr/bin/neutron-server

import sys
from neutron.server import main

if __name__ == "__main__":
sys.exit(main())

3. neutron.server.main

ef main():
# the configuration will be read into the cfg.CONF global data structure
config.init(sys.argv[1:])
if not cfg.CONF.config_file:
sys.exit(_("ERROR: Unable to find configuration file via the default"
" search paths (~/.neutron/, ~/, /etc/neutron/, /etc/) and"
" the '--config-file' option!"))
try:
pool = eventlet.GreenPool()

# 以协程方式启动Restful API
neutron_api = service.serve_wsgi(service.NeutronApiService)
api_thread = pool.spawn(neutron_api.wait)

# 启动RPC API
try:
neutron_rpc = service.serve_rpc()
except NotImplementedError:
LOG.info(_("RPC was already started in parent process by plugin."))
else:
rpc_thread = pool.spawn(neutron_rpc.wait)

# api and rpc should die together.  When one dies, kill the other.
rpc_thread.link(lambda gt: api_thread.kill())
api_thread.link(lambda gt: rpc_thread.kill())

pool.waitall()
except KeyboardInterrupt:
pass
except RuntimeError as e:
sys.exit(_("ERROR: %s") % e)

4. 先看neutron.service.serve_rpc()

neutron.service.serve_rpc()最重要的工作就是启动各个插件的RpcWorker

plugin = manager.NeutronManager.get_plugin()

try:
rpc = RpcWorker(plugin)

if cfg.CONF.rpc_workers < 1:
rpc.start()
return rpc
else:
launcher = common_service.ProcessLauncher(wait_interval=1.0)
launcher.launch_service(rpc, workers=cfg.CONF.rpc_workers)
return launcher

而RpcWorker最重要的工作是调用plugin的start_rpc_listeners来监听消息队列：

def start(self):
# We may have just forked from parent process.  A quick disposal of the
# existing sql connections avoids producing errors later when they are
# discovered to be broken.
session.get_engine().pool.dispose()
self._servers = self._plugin.start_rpc_listeners()

5. 再来看Rest API部分

service.serve_wsgi(service.NeutronApiService)

def serve_wsgi(cls):

try:
service = cls.create()
service.start()
except Exception:
with excutils.save_and_reraise_exception():
LOG.exception(_('Unrecoverable error: please check log '
'for details.'))

return service

service.start()

即为

self.wsgi_app = _run_wsgi(self.app_name)

，而该函数最重要的工作是从api-paste.ini中加载app并启动

def _run_wsgi(app_name):
app = config.load_paste_app(app_name)
if not app:
LOG.error(_('No known API applications configured.'))
return
server = wsgi.Server("Neutron")
server.start(app, cfg.CONF.bind_port, cfg.CONF.bind_host,
workers=cfg.CONF.api_workers)
# Dump all option values here after all options are parsed
cfg.CONF.log_opt_values(LOG, std_logging.DEBUG)
LOG.info(_("Neutron service started, listening on %(host)s:%(port)s"),
{'host': cfg.CONF.bind_host,
'port': cfg.CONF.bind_port})
return server

6. api-paste.ini

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

[composite:neutronapi_v2_0]
use = call:neutron.auth:pipeline_factory
noauth = request_id catch_errors extensions neutronapiapp_v2_0
keystone = request_id catch_errors authtoken keystonecontext extensions neutronapiapp_v2_0

[filter:request_id]
paste.filter_factory = neutron.openstack.common.middleware.request_id:RequestIdMiddleware.factory

[filter:catch_errors]
paste.filter_factory = neutron.openstack.common.middleware.catch_errors:CatchErrorsMiddleware.factory

[filter:keystonecontext]
paste.filter_factory = neutron.auth:NeutronKeystoneContext.factory

[filter:authtoken]
paste.filter_factory = keystoneclient.middleware.auth_token:filter_factory

[filter:extensions]
paste.filter_factory = neutron.api.extensions:plugin_aware_extension_middleware_factory

[app:neutronversions]
paste.app_factory = neutron.api.versions:Versions.factory

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

实例化neutron/api/v2/router.py中的APIRouter

class APIRouter(wsgi.Router):# 一个工厂类方法@classmethoddef factory(cls, global_config, **local_config):return cls(**local_config)# 真正调用的实例化方法def __init__(self, **local_config):...#获取NeutornManage的core_plugin，这个定义在/etc/neutron/neutron.conf,比如我的是#core_plugin = neutron.plugins.openvswitch.ovs_neutron_plugin.OVSNeutronPluginV2plugin = manager.NeutronManager.get_plugin()#扫描特定路径下的extensionsext_mgr = extensions.PluginAwareExtensionManager.get_instance()...#定义的局部方法def _map_resource(collection, resource, params, parent=None):...controller = base.create_resource(collection, resource, plugin, params, allow_bulk=allow_bulk,parent=parent, allow_pagination=allow_pagination,allow_sorting=allow_sorting)...# 将这些resource加进router中return mapper.collection(collection, resource, **mapper_kwargs)# 遍历 {'network': 'networks', 'subnet': 'subnets','port': 'ports'}# 添加controllerfor resource in RESOURCES:_map_resource(RESOURCES[resource], resource,attributes.RESOURCE_ATTRIBUTE_MAP.get(RESOURCES[resource], dict()))for resource in SUB_RESOURCES:...#其实操作和上面一个差不多，由这个可以看出，添加的controller类型主要分为三类：(其实只要你在neutron目录下grep一下，看哪里调用了

create_resource

方法即可)OVSNeutronPluginV2extensions/*.pyplugins/*.py针对前两途径加载resource的类，下面慢慢进行描述。至于第三种，则是在各个不同的plugin内部额外实现的，不是必须的。顺便简单的提一下，在

neutron/api/extensions.py

下的

get_instance

方法，这里其实也是和nova一样，是遍历目录下的py文件，来增加extension的...@classmethoddef get_instance(cls):if cls._instance is None:cls._instance = cls(get_extensions_path(),... NeutronManager.get_service_plugins())

Resource：OVSNeutronPluginV2的实现

看了代码的你肯定知道，

OVSNeutronPluginV2

这个类，作为

core_plugin

继承了好多的的类class OVSNeutronPluginV2(db_base_plugin_v2.NeutronDbPluginV2,external_net_db.External_net_db_mixin,extraroute_db.ExtraRoute_db_mixin,l3_gwmode_db.L3_NAT_db_mixin,sg_db_rpc.SecurityGroupServerRpcMixin,l3_agentschedulers_db.L3AgentSchedulerDbMixin,agentschedulers_db.DhcpAgentSchedulerDbMixin,portbindings_db.PortBindingMixin,extradhcpopt_db.ExtraDhcpOptMixin,addr_pair_db.AllowedAddressPairsMixin):

OVSNeutronPluginV2

基本上没有什么自己的method，全靠它的"爹们"了。随便抓两个来看下，比如

NeutronDbPluginV2

，他的method有

get_port

,

create_network

之类的，还有

L3_NAT_db_mixin

的

create_router

等。反正与db的操作，

OVSNeutronPluginV2

是不会管的，都在它的父类那边处理。再看看

OVSNeutronPluginV2

继承的这些父类们:#NeutronDbPluginV2继承自NeutronPluginBaseV2class NeutronDbPluginV2(neutron_plugin_base_v2.NeutronPluginBaseV2,CommonDbMixin):class NeutronPluginBaseV2(...) :@abstractmethoddef create_subnet(self, context, subnet):@abstractmethoddef update_subnet(self, context, id, subnet):@abstractmethoddef get_subnet(self, context, id, fields=None):@abstractmethoddef get_subnets(self, context, filters=None, fields=None,其类图如下:(仅展示部分)
基本上可以说有一个接口类(如图中的

NeutronPluginBaseV2

)，定义了抽象方法，然后一个具体的db类来实现(如

NeutronDbPluginV2

，这里是采用

SQLAlchemy

来完成db模型的)

plugin_aware_extension_middleware_factory

在请求进入APIRouter之前，会先经过RequestIdMiddleware（请求header中添加 openstack.request_id）、CatchErrorsMiddleware（错误处理）、keystone权限验证以及 plugin_aware_extension_middleware_factory等几个filter的处理，前三个filter比较直 观，plugin_aware_extension_middleware_factory初始化了Extension目录下的Resource：

class ExtensionMiddleware(wsgi.Middleware):
"""Extensions middleware for WSGI."""

def __init__(self, application,
ext_mgr=None):
self.ext_mgr = (ext_mgr
or ExtensionManager(get_extensions_path()))
mapper = routes.Mapper()

# extended resources ext_mgr.get_resources()其实在内部会调用每个extensions目录下的extension类的get_resources方法
for resource in self.ext_mgr.get_resources():
path_prefix = resource.path_prefix
if resource.parent:
path_prefix = (resource.path_prefix +
"/%s/{%s_id}" %
(resource.parent["collection_name"],
resource.parent["member_name"]))

LOG.debug(_('Extended resource: %s'),
resource.collection)
for action, method in resource.collection_actions.iteritems():
conditions = dict(method=[method])
path = "/%s/%s" % (resource.collection, action)
with mapper.submapper(controller=resource.controller,
action=action,
path_prefix=path_prefix,
conditions=conditions) as submap:
submap.connect(path)
submap.connect("%s.:(format)" % path)

mapper.resource(resource.collection, resource.collection,
controller=resource.controller,
member=resource.member_actions,
parent_resource=resource.parent,
path_prefix=path_prefix)

# extended actions
action_controllers = self._action_ext_controllers(application,
self.ext_mgr, mapper)
for action in self.ext_mgr.get_actions():
LOG.debug(_('Extended action: %s'), action.action_name)
controller = action_controllers[action.collection]
controller.add_action(action.action_name, action.handler)

# extended requests
req_controllers = self._request_ext_controllers(application,
self.ext_mgr, mapper)
for request_ext in self.ext_mgr.get_request_extensions():
LOG.debug(_('Extended request: %s'), request_ext.key)
controller = req_controllers[request_ext.key]
controller.add_handler(request_ext.handler)

self._router = routes.middleware.RoutesMiddleware(self._dispatch,
mapper)
super(ExtensionMiddleware, self).__init__(application)

比如在extensions下的

securitygroup

.py中的

get_resources

方法，看这个代码就知道其中可以处理

security_group

和

security_group_rule

两类请求了:

@classmethod
def get_resources(cls):
"""Returns Ext Resources."""
my_plurals = [(key, key[:-1]) for key in RESOURCE_ATTRIBUTE_MAP.keys()]
attr.PLURALS.update(dict(my_plurals))
exts = []
plugin = manager.NeutronManager.get_plugin()
for resource_name in ['security_group', 'security_group_rule']:
collection_name = resource_name.replace('_', '-') + "s"
params = RESOURCE_ATTRIBUTE_MAP.get(resource_name + "s", dict())
quota.QUOTAS.register_resource_by_name(resource_name)
controller = base.create_resource(collection_name,
resource_name,
plugin, params, allow_bulk=True,
allow_pagination=True,
allow_sorting=True)

ex = extensions.ResourceExtension(collection_name,
controller,
attr_map=params)
exts.append(ex)

return exts

如此，

Neutron-Server

就已经基本上启动了，无外乎就是加载配置，router各种resource，然后就等待请求了。其中router哪些resource完全是由配置文件来决定的。 当然，在启动的过程中也会初始化db，这也就是为何在安装

neutron

的时候无需像

nova

，

glance

等要执行

db sync

的原因了。

参考资料

Neutron网络简介 http://blog.ustack.com/blog/neutron_intro/
http://www.lnmpy.com/neutron-server-how-to-start/