# vim: tabstop=4 shiftwidth=4 softtabstop=4 # Copyright 2010 United States Government as represented by the # Administrator of the National Aeronautics and Space Administration. # Copyright 2010 OpenStack LLC. # All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"); you may # not use this file except in compliance with the License. You may obtain # a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the # License for the specific language governing permissions and limitations # under the License. """Utility methods for working with WSGI servers.""" import os.path import sys import eventlet import eventlet.wsgi import greenlet from paste import deploy import routes.middleware import webob.dec import webob.exc from nova import exception from nova import flags from nova.openstack.common import log as logging FLAGS = flags.FLAGS LOG = logging.getLogger(__name__) class Server(object): """Server class to manage a WSGI server, serving a WSGI application.""" default_pool_size = 1000 def __init__(self, name, app, host='0.0.0.0', port=0, pool_size=None, protocol=eventlet.wsgi.HttpProtocol, backlog=128): """Initialize, but do not start, a WSGI server. :param name: Pretty name for logging. :param app: The WSGI application to serve. :param host: IP address to serve the application. :param port: Port number to server the application. :param pool_size: Maximum number of eventlets to spawn concurrently. :param backlog: Maximum number of queued connections. :returns: None :raises: nova.exception.InvalidInput """ self.name = name self.app = app self._server = None self._protocol = protocol self._pool = eventlet.GreenPool(pool_size or self.default_pool_size) self._logger = logging.getLogger("nova.%s.wsgi.server" % self.name) self._wsgi_logger = logging.WritableLogger(self._logger) if backlog < 1: raise exception.InvalidInput( reason='The backlog must be more than 1') self._socket = eventlet.listen((host, port), backlog=backlog) (self.host, self.port) = self._socket.getsockname() LOG.info(_("%(name)s listening on %(host)s:%(port)s") % self.__dict__) def start(self): """Start serving a WSGI application. :returns: None """ self._server = eventlet.spawn(eventlet.wsgi.server, self._socket, self.app, protocol=self._protocol, custom_pool=self._pool, log=self._wsgi_logger) def stop(self): """Stop this server. This is not a very nice action, as currently the method by which a server is stopped is by killing its eventlet. :returns: None """ LOG.info(_("Stopping WSGI server.")) if self._server is not None: # Resize pool to stop new requests from being processed self._pool.resize(0) self._server.kill() def wait(self): """Block, until the server has stopped. Waits on the server's eventlet to finish, then returns. :returns: None """ try: self._server.wait() except greenlet.GreenletExit: LOG.info(_("WSGI server has stopped.")) class Request(webob.Request): pass class Application(object): """Base WSGI application wrapper. Subclasses need to implement __call__.""" @classmethod def factory(cls, global_config, **local_config): """Used for paste app factories in paste.deploy config files. Any local configuration (that is, values under the [app:APPNAME] section of the paste config) will be passed into the `__init__` method as kwargs. A hypothetical configuration would look like: [app:wadl] latest_version = 1.3 paste.app_factory = nova.api.fancy_api:Wadl.factory which would result in a call to the `Wadl` class as import nova.api.fancy_api fancy_api.Wadl(latest_version='1.3') You could of course re-implement the `factory` method in subclasses, but using the kwarg passing it shouldn't be necessary. """ return cls(**local_config) def __call__(self, environ, start_response): r"""Subclasses will probably want to implement __call__ like this: @webob.dec.wsgify(RequestClass=Request) def __call__(self, req): # Any of the following objects work as responses: # Option 1: simple string res = 'message\n' # Option 2: a nicely formatted HTTP exception page res = exc.HTTPForbidden(detail='Nice try') # Option 3: a webob Response object (in case you need to play with # headers, or you want to be treated like an iterable, or or or) res = Response(); res.app_iter = open('somefile') # Option 4: any wsgi app to be run next res = self.application # Option 5: you can get a Response object for a wsgi app, too, to # play with headers etc res = req.get_response(self.application) # You can then just return your response... return res # ... or set req.response and return None. req.response = res See the end of http://pythonpaste.org/webob/modules/dec.html for more info. """ raise NotImplementedError(_('You must implement __call__')) class Middleware(Application): """Base WSGI middleware. These classes require an application to be initialized that will be called next. By default the middleware will simply call its wrapped app, or you can override __call__ to customize its behavior. """ @classmethod def factory(cls, global_config, **local_config): """Used for paste app factories in paste.deploy config files. Any local configuration (that is, values under the [filter:APPNAME] section of the paste config) will be passed into the `__init__` method as kwargs. A hypothetical configuration would look like: [filter:analytics] redis_host = 127.0.0.1 paste.filter_factory = nova.api.analytics:Analytics.factory which would result in a call to the `Analytics` class as import nova.api.analytics analytics.Analytics(app_from_paste, redis_host='127.0.0.1') You could of course re-implement the `factory` method in subclasses, but using the kwarg passing it shouldn't be necessary. """ def _factory(app): return cls(app, **local_config) return _factory def __init__(self, application): self.application = application def process_request(self, req): """Called on each request. If this returns None, the next application down the stack will be executed. If it returns a response then that response will be returned and execution will stop here. """ return None def process_response(self, response): """Do whatever you'd like to the response.""" return response @webob.dec.wsgify(RequestClass=Request) def __call__(self, req): response = self.process_request(req) if response: return response response = req.get_response(self.application) return self.process_response(response) class Debug(Middleware): """Helper class for debugging a WSGI application. Can be inserted into any WSGI application chain to get information about the request and response. """ @webob.dec.wsgify(RequestClass=Request) def __call__(self, req): print ('*' * 40) + ' REQUEST ENVIRON' for key, value in req.environ.items(): print key, '=', value print resp = req.get_response(self.application) print ('*' * 40) + ' RESPONSE HEADERS' for (key, value) in resp.headers.iteritems(): print key, '=', value print resp.app_iter = self.print_generator(resp.app_iter) return resp @staticmethod def print_generator(app_iter): """Iterator that prints the contents of a wrapper string.""" print ('*' * 40) + ' BODY' for part in app_iter: sys.stdout.write(part) sys.stdout.flush() yield part print class Router(object): """WSGI middleware that maps incoming requests to WSGI apps.""" def __init__(self, mapper): """Create a router for the given routes.Mapper. Each route in `mapper` must specify a 'controller', which is a WSGI app to call. You'll probably want to specify an 'action' as well and have your controller be an object that can route the request to the action-specific method. Examples: mapper = routes.Mapper() sc = ServerController() # Explicit mapping of one route to a controller+action mapper.connect(None, '/svrlist', controller=sc, action='list') # Actions are all implicitly defined mapper.resource('server', 'servers', controller=sc) # Pointing to an arbitrary WSGI app. You can specify the # {path_info:.*} parameter so the target app can be handed just that # section of the URL. mapper.connect(None, '/v1.0/{path_info:.*}', controller=BlogApp()) """ self.map = mapper self._router = routes.middleware.RoutesMiddleware(self._dispatch, self.map) @webob.dec.wsgify(RequestClass=Request) def __call__(self, req): """Route the incoming request to a controller based on self.map. If no match, return a 404. """ return self._router @staticmethod @webob.dec.wsgify(RequestClass=Request) def _dispatch(req): """Dispatch the request to the appropriate controller. Called by self._router after matching the incoming request to a route and putting the information into req.environ. Either returns 404 or the routed WSGI app's response. """ match = req.environ['wsgiorg.routing_args'][1] if not match: return webob.exc.HTTPNotFound() app = match['controller'] return app class Loader(object): """Used to load WSGI applications from paste configurations.""" def __init__(self, config_path=None): """Initialize the loader, and attempt to find the config. :param config_path: Full or relative path to the paste config. :returns: None """ config_path = config_path or FLAGS.api_paste_config if os.path.exists(config_path): self.config_path = config_path else: self.config_path = FLAGS.find_file(config_path) if not self.config_path: raise exception.ConfigNotFound(path=config_path) def load_app(self, name): """Return the paste URLMap wrapped WSGI application. :param name: Name of the application to load. :returns: Paste URLMap object wrapping the requested application. :raises: `nova.exception.PasteAppNotFound` """ try: LOG.debug(_("Loading app %(name)s from %(path)s") % {'name': name, 'path': self.config_path}) return deploy.loadapp("config:%s" % self.config_path, name=name) except LookupError as err: LOG.error(err) raise exception.PasteAppNotFound(name=name, path=self.config_path)