375 lines
13 KiB
Python
375 lines
13 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# Copyright 2010 OpenStack LLC.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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Utility methods for working with WSGI servers
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"""
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import json
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import logging
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import sys
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from xml.dom import minidom
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import eventlet
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import eventlet.wsgi
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eventlet.patcher.monkey_patch(all=False, socket=True, time=True)
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import routes
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import routes.middleware
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import webob
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import webob.dec
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import webob.exc
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logging.getLogger("routes.middleware").addHandler(logging.StreamHandler())
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class Server(object):
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"""Server class to manage multiple WSGI sockets and applications."""
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def __init__(self, threads=1000):
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self.pool = eventlet.GreenPool(threads)
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def start(self, application, port, host='0.0.0.0', backlog=128):
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"""Run a WSGI server with the given application."""
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socket = eventlet.listen((host, port), backlog=backlog)
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self.pool.spawn_n(self._run, application, socket)
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def wait(self):
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"""Wait until all servers have completed running."""
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try:
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self.pool.waitall()
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except KeyboardInterrupt:
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pass
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def _run(self, application, socket):
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"""Start a WSGI server in a new green thread."""
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eventlet.wsgi.server(socket, application, custom_pool=self.pool)
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class Application(object):
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# TODO(gundlach): I think we should toss this class, now that it has no
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# purpose.
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"""Base WSGI application wrapper. Subclasses need to implement __call__."""
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def __call__(self, environ, start_response):
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r"""Subclasses will probably want to implement __call__ like this:
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@webob.dec.wsgify
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def __call__(self, req):
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# Any of the following objects work as responses:
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# Option 1: simple string
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res = 'message\n'
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# Option 2: a nicely formatted HTTP exception page
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res = exc.HTTPForbidden(detail='Nice try')
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# Option 3: a webob Response object (in case you need to play with
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# headers, or you want to be treated like an iterable, or or or)
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res = Response();
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res.app_iter = open('somefile')
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# Option 4: any wsgi app to be run next
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res = self.application
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# Option 5: you can get a Response object for a wsgi app, too, to
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# play with headers etc
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res = req.get_response(self.application)
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# You can then just return your response...
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return res
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# ... or set req.response and return None.
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req.response = res
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See the end of http://pythonpaste.org/webob/modules/dec.html
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for more info.
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"""
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raise NotImplementedError("You must implement __call__")
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class Middleware(Application):
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"""
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Base WSGI middleware wrapper. These classes require an application to be
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initialized that will be called next. By default the middleware will
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simply call its wrapped app, or you can override __call__ to customize its
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behavior.
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"""
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def __init__(self, application): # pylint: disable-msg=W0231
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self.application = application
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@webob.dec.wsgify
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def __call__(self, req): # pylint: disable-msg=W0221
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"""Override to implement middleware behavior."""
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return self.application
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class Debug(Middleware):
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"""Helper class that can be inserted into any WSGI application chain
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to get information about the request and response."""
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@webob.dec.wsgify
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def __call__(self, req):
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print ("*" * 40) + " REQUEST ENVIRON"
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for key, value in req.environ.items():
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print key, "=", value
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print
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resp = req.get_response(self.application)
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print ("*" * 40) + " RESPONSE HEADERS"
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for (key, value) in resp.headers.iteritems():
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print key, "=", value
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print
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resp.app_iter = self.print_generator(resp.app_iter)
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return resp
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@staticmethod
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def print_generator(app_iter):
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"""
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Iterator that prints the contents of a wrapper string iterator
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when iterated.
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"""
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print ("*" * 40) + " BODY"
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for part in app_iter:
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sys.stdout.write(part)
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sys.stdout.flush()
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yield part
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print
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class Router(object):
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"""
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WSGI middleware that maps incoming requests to WSGI apps.
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"""
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def __init__(self, mapper):
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"""
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Create a router for the given routes.Mapper.
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Each route in `mapper` must specify a 'controller', which is a
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WSGI app to call. You'll probably want to specify an 'action' as
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well and have your controller be a wsgi.Controller, who will route
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the request to the action method.
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Examples:
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mapper = routes.Mapper()
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sc = ServerController()
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# Explicit mapping of one route to a controller+action
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mapper.connect(None, "/svrlist", controller=sc, action="list")
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# Actions are all implicitly defined
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mapper.resource("server", "servers", controller=sc)
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# Pointing to an arbitrary WSGI app. You can specify the
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# {path_info:.*} parameter so the target app can be handed just that
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# section of the URL.
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mapper.connect(None, "/v1.0/{path_info:.*}", controller=BlogApp())
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"""
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self.map = mapper
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self._router = routes.middleware.RoutesMiddleware(self._dispatch,
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self.map)
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@webob.dec.wsgify
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def __call__(self, req):
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"""
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Route the incoming request to a controller based on self.map.
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If no match, return a 404.
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"""
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return self._router
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@staticmethod
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@webob.dec.wsgify
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def _dispatch(req):
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"""
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Called by self._router after matching the incoming request to a route
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and putting the information into req.environ. Either returns 404
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or the routed WSGI app's response.
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"""
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match = req.environ['wsgiorg.routing_args'][1]
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if not match:
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return webob.exc.HTTPNotFound()
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app = match['controller']
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return app
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class Controller(object):
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"""
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WSGI app that reads routing information supplied by RoutesMiddleware
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and calls the requested action method upon itself. All action methods
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must, in addition to their normal parameters, accept a 'req' argument
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which is the incoming webob.Request. They raise a webob.exc exception,
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or return a dict which will be serialized by requested content type.
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"""
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@webob.dec.wsgify
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def __call__(self, req):
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"""
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Call the method specified in req.environ by RoutesMiddleware.
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"""
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arg_dict = req.environ['wsgiorg.routing_args'][1]
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action = arg_dict['action']
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method = getattr(self, action)
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del arg_dict['controller']
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del arg_dict['action']
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arg_dict['req'] = req
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result = method(**arg_dict)
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if type(result) is dict:
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return self._serialize(result, req)
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else:
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return result
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def _serialize(self, data, request):
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"""
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Serialize the given dict to the response type requested in request.
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Uses self._serialization_metadata if it exists, which is a dict mapping
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MIME types to information needed to serialize to that type.
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"""
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_metadata = getattr(type(self), "_serialization_metadata", {})
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serializer = Serializer(request.environ, _metadata)
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return serializer.to_content_type(data)
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def _deserialize(self, data, request):
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"""
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Deserialize the request body to the response type requested in request.
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Uses self._serialization_metadata if it exists, which is a dict mapping
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MIME types to information needed to serialize to that type.
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"""
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_metadata = getattr(type(self), "_serialization_metadata", {})
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serializer = Serializer(request.environ, _metadata)
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return serializer.deserialize(data)
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class Serializer(object):
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"""
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Serializes and deserializes dictionaries to certain MIME types.
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"""
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def __init__(self, environ, metadata=None):
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"""
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Create a serializer based on the given WSGI environment.
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'metadata' is an optional dict mapping MIME types to information
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needed to serialize a dictionary to that type.
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"""
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self.metadata = metadata or {}
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req = webob.Request(environ)
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suffix = req.path_info.split('.')[-1].lower()
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if suffix == 'json':
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self.handler = self._to_json
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elif suffix == 'xml':
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self.handler = self._to_xml
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elif 'application/json' in req.accept:
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self.handler = self._to_json
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elif 'application/xml' in req.accept:
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self.handler = self._to_xml
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else:
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# This is the default
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self.handler = self._to_json
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def to_content_type(self, data):
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"""
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Serialize a dictionary into a string.
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The format of the string will be decided based on the Content Type
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requested in self.environ: by Accept: header, or by URL suffix.
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"""
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return self.handler(data)
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def deserialize(self, datastring):
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"""
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Deserialize a string to a dictionary.
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The string must be in the format of a supported MIME type.
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"""
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datastring = datastring.strip()
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try:
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is_xml = (datastring[0] == '<')
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if not is_xml:
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return json.loads(datastring)
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return self._from_xml(datastring)
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except:
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return None
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def _from_xml(self, datastring):
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xmldata = self.metadata.get('application/xml', {})
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plurals = set(xmldata.get('plurals', {}))
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node = minidom.parseString(datastring).childNodes[0]
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return {node.nodeName: self._from_xml_node(node, plurals)}
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def _from_xml_node(self, node, listnames):
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"""
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Convert a minidom node to a simple Python type.
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listnames is a collection of names of XML nodes whose subnodes should
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be considered list items.
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"""
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if len(node.childNodes) == 1 and node.childNodes[0].nodeType == 3:
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return node.childNodes[0].nodeValue
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elif node.nodeName in listnames:
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return [self._from_xml_node(n, listnames) for n in node.childNodes]
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else:
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result = dict()
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for attr in node.attributes.keys():
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result[attr] = node.attributes[attr].nodeValue
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for child in node.childNodes:
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if child.nodeType != node.TEXT_NODE:
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result[child.nodeName] = self._from_xml_node(child,
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listnames)
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return result
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def _to_json(self, data):
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return json.dumps(data)
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def _to_xml(self, data):
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metadata = self.metadata.get('application/xml', {})
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# We expect data to contain a single key which is the XML root.
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root_key = data.keys()[0]
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doc = minidom.Document()
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node = self._to_xml_node(doc, metadata, root_key, data[root_key])
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return node.toprettyxml(indent=' ')
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def _to_xml_node(self, doc, metadata, nodename, data):
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"""Recursive method to convert data members to XML nodes."""
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result = doc.createElement(nodename)
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if type(data) is list:
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singular = metadata.get('plurals', {}).get(nodename, None)
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if singular is None:
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if nodename.endswith('s'):
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singular = nodename[:-1]
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else:
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singular = 'item'
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for item in data:
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node = self._to_xml_node(doc, metadata, singular, item)
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result.appendChild(node)
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elif type(data) is dict:
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attrs = metadata.get('attributes', {}).get(nodename, {})
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for k, v in data.items():
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if k in attrs:
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result.setAttribute(k, str(v))
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else:
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node = self._to_xml_node(doc, metadata, k, v)
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result.appendChild(node)
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else:
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# Type is atom
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node = doc.createTextNode(str(data))
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result.appendChild(node)
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return result
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