383 lines
12 KiB
Python
383 lines
12 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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"""Utility methods for working with WSGI servers."""
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import os.path
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import sys
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import eventlet
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import eventlet.wsgi
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import greenlet
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from paste import deploy
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import routes.middleware
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import webob.dec
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import webob.exc
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from nova import exception
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from nova import flags
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from nova import log as logging
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from nova import utils
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FLAGS = flags.FLAGS
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LOG = logging.getLogger(__name__)
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class Server(object):
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"""Server class to manage a WSGI server, serving a WSGI application."""
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default_pool_size = 1000
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def __init__(self, name, app, host=None, port=None, pool_size=None,
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protocol=eventlet.wsgi.HttpProtocol):
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"""Initialize, but do not start, a WSGI server.
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:param name: Pretty name for logging.
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:param app: The WSGI application to serve.
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:param host: IP address to serve the application.
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:param port: Port number to server the application.
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:param pool_size: Maximum number of eventlets to spawn concurrently.
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:returns: None
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"""
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self.name = name
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self.app = app
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self.host = host or "0.0.0.0"
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self.port = port or 0
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self._server = None
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self._socket = None
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self._protocol = protocol
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self._pool = eventlet.GreenPool(pool_size or self.default_pool_size)
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self._logger = logging.getLogger("eventlet.wsgi.server")
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self._wsgi_logger = logging.WritableLogger(self._logger)
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def _start(self):
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"""Run the blocking eventlet WSGI server.
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:returns: None
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"""
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eventlet.wsgi.server(self._socket,
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self.app,
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protocol=self._protocol,
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custom_pool=self._pool,
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log=self._wsgi_logger)
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def start(self, backlog=128):
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"""Start serving a WSGI application.
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:param backlog: Maximum number of queued connections.
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:returns: None
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:raises: nova.exception.InvalidInput
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"""
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if backlog < 1:
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raise exception.InvalidInput(
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reason='The backlog must be more than 1')
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self._socket = eventlet.listen((self.host, self.port), backlog=backlog)
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self._server = eventlet.spawn(self._start)
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(self.host, self.port) = self._socket.getsockname()
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LOG.info(_("Started %(name)s on %(host)s:%(port)s") % self.__dict__)
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def stop(self):
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"""Stop this server.
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This is not a very nice action, as currently the method by which a
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server is stopped is by killing its eventlet.
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:returns: None
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"""
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LOG.info(_("Stopping WSGI server."))
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self._server.kill()
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def wait(self):
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"""Block, until the server has stopped.
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Waits on the server's eventlet to finish, then returns.
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:returns: None
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"""
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try:
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self._server.wait()
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except greenlet.GreenletExit:
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LOG.info(_("WSGI server has stopped."))
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class Request(webob.Request):
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pass
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class Application(object):
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"""Base WSGI application wrapper. Subclasses need to implement __call__."""
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@classmethod
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def factory(cls, global_config, **local_config):
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"""Used for paste app factories in paste.deploy config files.
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Any local configuration (that is, values under the [app:APPNAME]
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section of the paste config) will be passed into the `__init__` method
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as kwargs.
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A hypothetical configuration would look like:
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[app:wadl]
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latest_version = 1.3
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paste.app_factory = nova.api.fancy_api:Wadl.factory
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which would result in a call to the `Wadl` class as
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import nova.api.fancy_api
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fancy_api.Wadl(latest_version='1.3')
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You could of course re-implement the `factory` method in subclasses,
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but using the kwarg passing it shouldn't be necessary.
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"""
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return cls(**local_config)
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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(RequestClass=Request)
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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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"""Base WSGI middleware.
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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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@classmethod
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def factory(cls, global_config, **local_config):
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"""Used for paste app factories in paste.deploy config files.
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Any local configuration (that is, values under the [filter:APPNAME]
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section of the paste config) will be passed into the `__init__` method
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as kwargs.
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A hypothetical configuration would look like:
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[filter:analytics]
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redis_host = 127.0.0.1
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paste.filter_factory = nova.api.analytics:Analytics.factory
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which would result in a call to the `Analytics` class as
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import nova.api.analytics
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analytics.Analytics(app_from_paste, redis_host='127.0.0.1')
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You could of course re-implement the `factory` method in subclasses,
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but using the kwarg passing it shouldn't be necessary.
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"""
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def _factory(app):
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return cls(app, **local_config)
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return _factory
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def __init__(self, application):
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self.application = application
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def process_request(self, req):
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"""Called on each request.
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If this returns None, the next application down the stack will be
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executed. If it returns a response then that response will be returned
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and execution will stop here.
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"""
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return None
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def process_response(self, response):
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"""Do whatever you'd like to the response."""
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return response
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@webob.dec.wsgify(RequestClass=Request)
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def __call__(self, req):
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response = self.process_request(req)
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if response:
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return response
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response = req.get_response(self.application)
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return self.process_response(response)
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class Debug(Middleware):
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"""Helper class for debugging a WSGI application.
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Can be inserted into any WSGI application chain to get information
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about the request and response.
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"""
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@webob.dec.wsgify(RequestClass=Request)
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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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"""Iterator that prints the contents of a wrapper string."""
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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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"""WSGI middleware that maps incoming requests to WSGI apps."""
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def __init__(self, mapper):
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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 an object that can route
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the request to the action-specific 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(RequestClass=Request)
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def __call__(self, req):
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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(RequestClass=Request)
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def _dispatch(req):
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"""Dispatch the request to the appropriate controller.
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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 Loader(object):
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"""Used to load WSGI applications from paste configurations."""
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def __init__(self, config_path=None):
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"""Initialize the loader, and attempt to find the config.
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:param config_path: Full or relative path to the paste config.
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:returns: None
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"""
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config_path = config_path or FLAGS.api_paste_config
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if os.path.exists(config_path):
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self.config_path = config_path
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else:
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self.config_path = FLAGS.find_file(config_path)
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if not self.config_path:
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raise exception.ConfigNotFound(path=config_path)
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def load_app(self, name):
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"""Return the paste URLMap wrapped WSGI application.
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:param name: Name of the application to load.
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:returns: Paste URLMap object wrapping the requested application.
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:raises: `nova.exception.PasteAppNotFound`
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"""
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try:
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LOG.debug(_("Loading app %(name)s from %(path)s") %
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{'name': name, 'path': self.config_path})
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return deploy.loadapp("config:%s" % self.config_path, name=name)
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except LookupError as err:
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LOG.error(err)
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raise exception.PasteAppNotFound(name=name, path=self.config_path)
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