OpenStack Networking (Neutron)
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2011, Nicira Networks, Inc.
# 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
# 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 json
import logging
import sys
import datetime
from xml.dom import minidom
import eventlet
import eventlet.wsgi
eventlet.patcher.monkey_patch(all=False, socket=True)
import routes
import routes.middleware
import webob.dec
import webob.exc
from quantum import utils
from quantum.common import exceptions as exception
LOG = logging.getLogger('quantum.common.wsgi')
class WritableLogger(object):
"""A thin wrapper that responds to `write` and logs."""
def __init__(self, logger, level=logging.DEBUG):
self.logger = logger
self.level = level
def write(self, msg):
self.logger.log(self.level, msg.strip("\n"))
def run_server(application, port):
"""Run a WSGI server with the given application."""
sock = eventlet.listen(('', port))
eventlet.wsgi.server(sock, application)
class Server(object):
"""Server class to manage multiple WSGI sockets and applications."""
def __init__(self, threads=1000):
self.pool = eventlet.GreenPool(threads)
def start(self, application, port, host='', backlog=128):
"""Run a WSGI server with the given application."""
socket = eventlet.listen((host, port), backlog=backlog)
self.pool.spawn_n(self._run, application, socket)
def wait(self):
"""Wait until all servers have completed running."""
except KeyboardInterrupt:
def _run(self, application, socket):
"""Start a WSGI server in a new green thread."""
logger = logging.getLogger('eventlet.wsgi.server')
eventlet.wsgi.server(socket, application, custom_pool=self.pool,
class Middleware(object):
Base WSGI middleware wrapper. 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
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
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 Request(webob.Request):
def best_match_content_type(self):
"""Determine the most acceptable content-type.
Based on the query extension then the Accept header.
parts = self.path.rsplit('.', 1)
LOG.debug("Request parts:%s", parts)
if len(parts) > 1:
format = parts[1]
if format in ['json', 'xml']:
return 'application/{0}'.format(parts[1])
ctypes = ['application/json', 'application/xml']
bm = self.accept.best_match(ctypes)
return bm or 'application/json'
def get_content_type(self):
allowed_types = ("application/xml", "application/json")
if not "Content-Type" in self.headers:
msg = _("Missing Content-Type")
raise webob.exc.HTTPBadRequest(msg)
type = self.content_type
if type in allowed_types:
return type
LOG.debug(_("Wrong Content-Type: %s") % type)
raise webob.exc.HTTPBadRequest("Invalid content type")
class Application(object):
"""Base WSGI application wrapper. Subclasses need to implement __call__."""
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:
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 quantum.api.fancy_api
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:
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
for more info.
raise NotImplementedError(_('You must implement __call__'))
class Debug(Middleware):
Helper class that can be inserted into any WSGI application chain
to get information about the request and response.
def __call__(self, req):
print ("*" * 40) + " REQUEST ENVIRON"
for key, value in req.environ.items():
print key, "=", value
resp = req.get_response(self.application)
print ("*" * 40) + " RESPONSE HEADERS"
for (key, value) in resp.headers.iteritems():
print key, "=", value
resp.app_iter = self.print_generator(resp.app_iter)
return resp
def print_generator(app_iter):
Iterator that prints the contents of a wrapper string iterator
when iterated.
print ("*" * 40) + " BODY"
for part in app_iter:
yield part
class Router(object):
WSGI middleware that maps incoming requests to WSGI apps.
def factory(cls, global_config, **local_config):
Returns an instance of the WSGI Router class
return cls()
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 a wsgi.Controller, who will route
the request to the action method.
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("network", "networks", controller=nc)
# 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())
""" = mapper
self._router = routes.middleware.RoutesMiddleware(self._dispatch,
def __call__(self, req):
Route the incoming request to a controller based on
If no match, return a 404.
LOG.debug("HERE - wsgi.Router.__call__")
return self._router
def _dispatch(req):
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 Controller(object):
"""WSGI app that dispatched to methods.
WSGI app that reads routing information supplied by RoutesMiddleware
and calls the requested action method upon itself. All action methods
must, in addition to their normal parameters, accept a 'req' argument
which is the incoming wsgi.Request. They raise a webob.exc exception,
or return a dict which will be serialized by requested content type.
def __call__(self, req):
Call the method specified in req.environ by RoutesMiddleware.
LOG.debug("HERE - wsgi.Controller.__call__")
arg_dict = req.environ['wsgiorg.routing_args'][1]
action = arg_dict['action']
method = getattr(self, action)
del arg_dict['controller']
del arg_dict['action']
if 'format' in arg_dict:
del arg_dict['format']
arg_dict['req'] = req
result = method(**arg_dict)
if type(result) is dict:
content_type = req.best_match_content_type()
default_xmlns = self.get_default_xmlns(req)
body = self._serialize(result, content_type, default_xmlns)
response = webob.Response()
response.headers['Content-Type'] = content_type
response.body = body
msg_dict = dict(url=req.url, status=response.status_int)
msg = _("%(url)s returned with HTTP %(status)d") % msg_dict
return response
return result
def _serialize(self, data, content_type, default_xmlns):
"""Serialize the given dict to the provided content_type.
Uses self._serialization_metadata if it exists, which is a dict mapping
MIME types to information needed to serialize to that type.
_metadata = getattr(type(self), '_serialization_metadata', {})
serializer = Serializer(_metadata, default_xmlns)
return serializer.serialize(data, content_type)
except exception.InvalidContentType:
raise webob.exc.HTTPNotAcceptable()
def _deserialize(self, data, content_type):
"""Deserialize the request body to the specefied content type.
Uses self._serialization_metadata if it exists, which is a dict mapping
MIME types to information needed to serialize to that type.
_metadata = getattr(type(self), '_serialization_metadata', {})
serializer = Serializer(_metadata)
return serializer.deserialize(data, content_type)
def get_default_xmlns(self, req):
"""Provide the XML namespace to use if none is otherwise specified."""
return None
class Serializer(object):
"""Serializes and deserializes dictionaries to certain MIME types."""
def __init__(self, metadata=None, default_xmlns=None):
"""Create a serializer based on the given WSGI environment.
'metadata' is an optional dict mapping MIME types to information
needed to serialize a dictionary to that type.
self.metadata = metadata or {}
self.default_xmlns = default_xmlns
def _get_serialize_handler(self, content_type):
handlers = {
'application/json': self._to_json,
'application/xml': self._to_xml,
return handlers[content_type]
except Exception:
raise exception.InvalidContentType(content_type=content_type)
def serialize(self, data, content_type):
"""Serialize a dictionary into the specified content type."""
return self._get_serialize_handler(content_type)(data)
def deserialize(self, datastring, content_type):
"""Deserialize a string to a dictionary.
The string must be in the format of a supported MIME type.
return self.get_deserialize_handler(content_type)(datastring)
def get_deserialize_handler(self, content_type):
handlers = {
'application/json': self._from_json,
'application/xml': self._from_xml,
return handlers[content_type]
except Exception:
raise exception.InvalidContentType(content_type=content_type)
def _from_json(self, datastring):
return utils.loads(datastring)
def _from_xml(self, datastring):
xmldata = self.metadata.get('application/xml', {})
plurals = set(xmldata.get('plurals', {}))
node = minidom.parseString(datastring).childNodes[0]
return {node.nodeName: self._from_xml_node(node, plurals)}
def _from_xml_node(self, node, listnames):
"""Convert a minidom node to a simple Python type.
listnames is a collection of names of XML nodes whose subnodes should
be considered list items.
if len(node.childNodes) == 1 and node.childNodes[0].nodeType == 3:
return node.childNodes[0].nodeValue
elif node.nodeName in listnames:
return [self._from_xml_node(n, listnames) for n in node.childNodes]
result = dict()
for attr in node.attributes.keys():
result[attr] = node.attributes[attr].nodeValue
for child in node.childNodes:
if child.nodeType != node.TEXT_NODE:
result[child.nodeName] = self._from_xml_node(child,
return result
def _to_json(self, data):
return utils.dumps(data)
def _to_xml(self, data):
metadata = self.metadata.get('application/xml', {})
# We expect data to contain a single key which is the XML root.
root_key = data.keys()[0]
doc = minidom.Document()
node = self._to_xml_node(doc, metadata, root_key, data[root_key])
xmlns = node.getAttribute('xmlns')
if not xmlns and self.default_xmlns:
node.setAttribute('xmlns', self.default_xmlns)
return node.toprettyxml(indent=' ')
def _to_xml_node(self, doc, metadata, nodename, data):
"""Recursive method to convert data members to XML nodes."""
result = doc.createElement(nodename)
# Set the xml namespace if one is specified
# TODO(justinsb): We could also use prefixes on the keys
xmlns = metadata.get('xmlns', None)
if xmlns:
result.setAttribute('xmlns', xmlns)
if type(data) is list:
collections = metadata.get('list_collections', {})
if nodename in collections:
metadata = collections[nodename]
for item in data:
node = doc.createElement(metadata['item_name'])
node.setAttribute(metadata['item_key'], str(item))
return result
singular = metadata.get('plurals', {}).get(nodename, None)
if singular is None:
if nodename.endswith('s'):
singular = nodename[:-1]
singular = 'item'
for item in data:
node = self._to_xml_node(doc, metadata, singular, item)
elif type(data) is dict:
collections = metadata.get('dict_collections', {})
if nodename in collections:
metadata = collections[nodename]
for k, v in data.items():
node = doc.createElement(metadata['item_name'])
node.setAttribute(metadata['item_key'], str(k))
text = doc.createTextNode(str(v))
return result
attrs = metadata.get('attributes', {}).get(nodename, {})
for k, v in data.items():
if k in attrs:
result.setAttribute(k, str(v))
node = self._to_xml_node(doc, metadata, k, v)
# Type is atom
node = doc.createTextNode(str(data))
return result