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

  1. class APIRouter(wsgi.Router):
  2. # 一个工厂类方法
  3. @classmethod
  4. def factory(cls, global_config, **local_config):
  5. return cls(**local_config)
  6. # 真正调用的实例化方法
  7. def __init__(self, **local_config):
  8. ...
  9. #获取NeutornManage的core_plugin,这个定义在/etc/neutron/neutron.conf,比如我的是
  10. #core_plugin = neutron.plugins.openvswitch.ovs_neutron_plugin.OVSNeutronPluginV2
  11. plugin = manager.NeutronManager.get_plugin()
  12. #扫描特定路径下的extensions
  13. ext_mgr = extensions.PluginAwareExtensionManager.get_instance()
  14. ...
  15. #定义的局部方法
  16. def _map_resource(collection, resource, params, parent=None):
  17. ...
  18. controller = base.create_resource(
  19. collection, resource, plugin, params, allow_bulk=allow_bulk,
  20. parent=parent, allow_pagination=allow_pagination,
  21. allow_sorting=allow_sorting)
  22. ...
  23. # 将这些resource加进router中
  24. return mapper.collection(collection, resource, **mapper_kwargs)
  25. # 遍历 {'network': 'networks', 'subnet': 'subnets','port': 'ports'}
  26. # 添加controller
  27. for resource in RESOURCES:
  28. _map_resource(RESOURCES[resource], resource,
  29. attributes.RESOURCE_ATTRIBUTE_MAP.get(
  30. RESOURCES[resource], dict()))
  31. for resource in SUB_RESOURCES:
  32. ...
  33. #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)

  1. OVSNeutronPluginV2
  2. extensions/*.py
  3. plugins/*.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

  1. ...
  2. @classmethod
  3. def get_instance(cls):
  4. if cls._instance is None:
  5. cls._instance = cls(get_extensions_path(),
  6. ... 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

  1. class OVSNeutronPluginV2(db_base_plugin_v2.NeutronDbPluginV2,
  2. external_net_db.External_net_db_mixin,
  3. extraroute_db.ExtraRoute_db_mixin,
  4. l3_gwmode_db.L3_NAT_db_mixin,
  5. sg_db_rpc.SecurityGroupServerRpcMixin,
  6. l3_agentschedulers_db.L3AgentSchedulerDbMixin,
  7. agentschedulers_db.DhcpAgentSchedulerDbMixin,
  8. portbindings_db.PortBindingMixin,
  9. extradhcpopt_db.ExtraDhcpOptMixin,
  10. 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_mixincreate_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:

  1. #NeutronDbPluginV2继承自NeutronPluginBaseV2
  2. class NeutronDbPluginV2(neutron_plugin_base_v2.NeutronPluginBaseV2,
  3. CommonDbMixin):
  4. class NeutronPluginBaseV2(...) :
  5. @abstractmethod
  6. def create_subnet(self, context, subnet):
  7. @abstractmethod
  8. def update_subnet(self, context, id, subnet):
  9. @abstractmethod
  10. def get_subnet(self, context, id, fields=None):
  11. @abstractmethod
  12. def get_subnets(self, context, filters=None, fields=None,

其类图如下:(仅展示部分) Neutron分析(2)——neutron-server启动过程分析

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_groupsecurity_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novaglance等要执行db sync的原因了。



参考资料

上一篇:[LOJ#2326]「清华集训 2017」简单数据结构


下一篇:mapgis处理编辑属性结构时 死机问题