582 lines
19 KiB
Python
582 lines
19 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 os
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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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from paste import deploy
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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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class WritableLogger(object):
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"""A thin wrapper that responds to `write` and logs."""
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def __init__(self, logger, level=logging.DEBUG):
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self.logger = logger
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self.level = level
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def write(self, msg):
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self.logger.log(self.level, msg)
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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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arg0 = sys.argv[0]
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logging.audit(_("Starting %(arg0)s on %(host)s:%(port)s") % locals())
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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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logger = logging.getLogger('eventlet.wsgi.server')
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eventlet.wsgi.server(socket, application, custom_pool=self.pool,
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log=WritableLogger(logger))
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class Request(webob.Request):
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def best_match_content_type(self):
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"""
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Determine the most acceptable content-type based on the
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query extension then the Accept header
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"""
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parts = self.path.rsplit(".", 1)
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if len(parts) > 1:
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format = parts[1]
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if format in ["json", "xml"]:
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return "application/{0}".format(parts[1])
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ctypes = ["application/json", "application/xml"]
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bm = self.accept.best_match(ctypes)
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return bm or "application/json"
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def get_content_type(self):
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try:
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ct = self.headers["Content-Type"]
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assert ct in ("application/xml", "application/json")
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return ct
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except Exception:
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raise webob.exc.HTTPBadRequest("Invalid content type")
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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 fles.
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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 fles.
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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 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(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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"""
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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(RequestClass=Request)
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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(RequestClass=Request)
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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 wsgi.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(RequestClass=Request)
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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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if 'format' in arg_dict:
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del arg_dict['format']
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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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content_type = req.best_match_content_type()
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default_xmlns = self.get_default_xmlns(req)
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body = self._serialize(result, content_type, default_xmlns)
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response = webob.Response()
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response.headers["Content-Type"] = content_type
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response.body = body
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return response
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else:
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return result
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def _serialize(self, data, content_type, default_xmlns):
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"""
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Serialize the given dict to the provided content_type.
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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(_metadata, default_xmlns)
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try:
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return serializer.serialize(data, content_type)
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except exception.InvalidContentType:
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raise webob.exc.HTTPNotAcceptable()
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def _deserialize(self, data, content_type):
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"""
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Deserialize the request body to the specefied content type.
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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(_metadata)
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return serializer.deserialize(data, content_type)
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def get_default_xmlns(self, req):
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"""Provide the XML namespace to use if none is otherwise specified."""
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return None
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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, metadata=None, default_xmlns=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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self.default_xmlns = default_xmlns
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def _get_serialize_handler(self, content_type):
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handlers = {
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"application/json": self._to_json,
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"application/xml": self._to_xml,
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}
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try:
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return handlers[content_type]
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except Exception:
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raise exception.InvalidContentType()
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def serialize(self, data, content_type):
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"""
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Serialize a dictionary into a string of the specified content type.
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"""
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return self._get_serialize_handler(content_type)(data)
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def deserialize(self, datastring, content_type):
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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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return self.get_deserialize_handler(content_type)(datastring)
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def get_deserialize_handler(self, content_type):
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handlers = {
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"application/json": self._from_json,
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"application/xml": self._from_xml,
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}
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try:
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return handlers[content_type]
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except Exception:
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raise exception.InvalidContentType(_("Invalid content type %s"
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% content_type))
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def _from_json(self, datastring):
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return utils.loads(datastring)
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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 utils.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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xmlns = node.getAttribute('xmlns')
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if not xmlns and self.default_xmlns:
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node.setAttribute('xmlns', self.default_xmlns)
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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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# Set the xml namespace if one is specified
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# TODO(justinsb): We could also use prefixes on the keys
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xmlns = metadata.get('xmlns', None)
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if xmlns:
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result.setAttribute('xmlns', xmlns)
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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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def paste_config_file(basename):
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"""Find the best location in the system for a paste config file.
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Search Order
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------------
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The search for a paste config file honors `FLAGS.state_path`, which in a
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version checked out from bzr will be the `nova` directory in the top level
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of the checkout, and in an installation for a package for your distribution
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will likely point to someplace like /etc/nova.
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This method tries to load places likely to be used in development or
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experimentation before falling back to the system-wide configuration
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in `/etc/nova/`.
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|
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* Current working directory
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|
* the `etc` directory under state_path, because when working on a checkout
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from bzr this will point to the default
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* top level of FLAGS.state_path, for distributions
|
|
* /etc/nova, which may not be diffrerent from state_path on your distro
|
|
|
|
"""
|
|
|
|
configfiles = [basename,
|
|
os.path.join(FLAGS.state_path, 'etc', 'nova', basename),
|
|
os.path.join(FLAGS.state_path, 'etc', basename),
|
|
os.path.join(FLAGS.state_path, basename),
|
|
'/etc/nova/%s' % basename]
|
|
for configfile in configfiles:
|
|
if os.path.exists(configfile):
|
|
return configfile
|
|
|
|
|
|
def load_paste_configuration(filename, appname):
|
|
"""Returns a paste configuration dict, or None."""
|
|
filename = os.path.abspath(filename)
|
|
config = None
|
|
try:
|
|
config = deploy.appconfig("config:%s" % filename, name=appname)
|
|
except LookupError:
|
|
pass
|
|
return config
|
|
|
|
|
|
def load_paste_app(filename, appname):
|
|
"""Builds a wsgi app from a paste config, None if app not configured."""
|
|
filename = os.path.abspath(filename)
|
|
app = None
|
|
try:
|
|
app = deploy.loadapp("config:%s" % filename, name=appname)
|
|
except LookupError:
|
|
pass
|
|
return app
|