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概述:
這篇博客關注的問題就是:
請求信息如何通過swift-proxy服務實現轉發;
這裏應用網上找到的一幅圖片來看看swift-proxy服務在swift系統中的作用(多謝作者);
簡單說,請求過來之後,通過swift-proxy服務的服務入口點,調用swift-proxy服務上的相關方法,實現通過給定的請求來確定具體要獲取的控制器(ObjectController、ContainerController、AccountController),並進一步調用控制器下的具體方法,實現到相應存儲服務(Object-server、Container-server、Account-server)的連接,並具體調用相應的方法來實現請求;
下面來看看代碼的實現:
def __call__(self, env, start_response):
"""
調用WSGI服務的入口點;
"""
try:
# 獲取緩存信息;
# 在env中獲取'swift.cache'的值,如果爲none,則報錯誤提示;
# 注:env:表示wsgi環境的字典;
if self.memcache is None:
self.memcache = cache_from_env(env)
req = self.update_request(Request(env))
return self.handle_request(req)(env, start_response)
except UnicodeError:
err = HTTPPreconditionFailed(request=req, body='Invalid UTF8 or contains NULL')
return err(env, start_response)
except (Exception, Timeout):
start_response('500 Server Error',[('Content-Type', 'text/plain')])
return ['Internal server error.\n']
方法handle_request實現了對HTTP傳遞過來的請求進行具體的處理和執行,來看方法handle_request的實現:
def handle_request(self, req):
"""
代理服務的入口點;
對HTTP請求進行具體的處理和執行等操作;
"""
try:
self.logger.set_statsd_prefix('proxy-server')
if req.content_length and req.content_length < 0:
self.logger.increment('errors')
return HTTPBadRequest(request=req, body='Invalid Content-Length')
try:
if not check_utf8(req.path_info):
self.logger.increment('errors')
return HTTPPreconditionFailed(request=req, body='Invalid UTF8 or contains NULL')
except UnicodeError:
self.logger.increment('errors')
return HTTPPreconditionFailed(request=req, body='Invalid UTF8 or contains NULL')
try:
# 根據給定的HTTP的請求路徑path獲取控制器來處理請求;
# 如果account, container, object都存在,則獲取ObjectController控制器;
# 如果account, container存在,object不存在,則獲取ContainerController控制器;
# 如果account存在,container, object不存在,則獲取AccountController控制器;
# 返回值:
# path_parts:version, account, container, object等值的字典;
# controller:具體的控制器類實例化對象;
controller, path_parts = self.get_controller(req.path)
# req.path = /v1/AUTH_2a8cbfbb8ad7411c8465f57311527937/testcontainer2/ceph9
# controller = <class 'swift.proxy.controllers.obj.ObjectController'>
# path_parts = {'object_name': 'ceph9', 'version': 'v1',
# 'account_name': 'AUTH_2a8cbfbb8ad7411c8465f57311527937',
# 'container_name': 'testcontainer2'}
p = req.path_info
if isinstance(p, unicode):
p = p.encode('utf-8')
except ValueError:
self.logger.increment('errors')
return HTTPNotFound(request=req)
if not controller:
self.logger.increment('errors')
return HTTPPreconditionFailed(request=req, body='Bad URL')
if self.deny_host_headers and req.host.split(':')[0] in self.deny_host_headers:
return HTTPForbidden(request=req, body='Invalid host header')
# server_type:不同的類定義了不同的server_type;
# server_type = 'Object';
# server_type = 'Account';
# server_type = 'Base';
# server_type = 'Container';
self.logger.set_statsd_prefix('proxy-server.' + controller.server_type.lower())
# 獲取控制器類的實例化對象;
controller = controller(self, **path_parts)
if 'swift.trans_id' not in req.environ:
# if this wasn't set by an earlier middleware, set it now
trans_id = generate_trans_id(self.trans_id_suffix)
req.environ['swift.trans_id'] = trans_id
self.logger.txn_id = trans_id
req.headers['x-trans-id'] = req.environ['swift.trans_id']
controller.trans_id = req.environ['swift.trans_id']
self.logger.client_ip = get_remote_client(req)
try:
# 執行具體控制器類中的指定方法;
handler = getattr(controller, req.method)
# req.method = DELETE
# controller = <swift.proxy.controllers.obj.ObjectController object at 0x2acc110>
# handler = <bound method ObjectController.DELETE of <swift.proxy.controllers.obj.ObjectController object at 0x2acc110>>
getattr(handler, 'publicly_accessible')
except AttributeError:
allowed_methods = getattr(controller, 'allowed_methods', set())
return HTTPMethodNotAllowed(request=req, headers={'Allow': ', '.join(allowed_methods)})
if 'swift.authorize' in req.environ:
resp = req.environ['swift.authorize'](req)
if not resp:
del req.environ['swift.authorize']
else:
if not getattr(handler, 'delay_denial', None):
return resp
req.environ['swift.orig_req_method'] = req.method
# handler = <bound method ObjectController.DELETE of <swift.proxy.controllers.obj.ObjectController object at 0x2acc110>>
return handler(req)
except HTTPException as error_response:
return error_response
except (Exception, Timeout):
self.logger.exception(_('ERROR Unhandled exception in request'))
return HTTPServerError(request=req)
1.controller, path_parts = self.get_controller(req.path)根據給定的HTTP的請求路徑path獲取控制器(ObjectController、ContainerController、AccountController)來處理請求;
2.controller = controller(self, **path_parts)
獲取控制器類的實例化對象;
3.handler = getattr(controller, req.method)
執行具體控制器類中的指定方法;
4.return handler(req)
調用相應控制器中具體的方法來對req進行處理;
接下來將要調用的就是/swift/proxy/controllers/account.py或/swift/proxy/controllers/container.py或/swift/proxy/controllers/obj.py下面的PUT,POST,DELETE,GET,HEAD等方法;然後再在具體的方法中實現到具體存儲服務(Object-server、Container-server、Account-server)的連接,繼而調用其下具體的PUT,POST,DELETE,GET,HEAD等方法來進行請求req的實現;