openstack/oslo.messaging
Code Issues Proposed changes

Add a TransportURL class to the public API

Browse Source 
Nova's cells/rpc_driver.py has some code which allows user of the REST
API to update elements of a cell's transport URL (say, the host name of
the message broker) stored in the database. To achieve this, it has
a parse_transport_url() method which breaks the URL into its constituent
parts and an unparse_transport_url() which re-forms it again after
updating some of its parts.

This is all fine and, since it's fairly specialized, it wouldn't be a
big deal to leave this code in Nova for now ... except the unparse
method looks at CONF.rpc_backend to know what scheme to use in the
returned URL if now backend was specified.

oslo.messaging registers the rpc_backend option, but the ability to
reference any option registered by the library should not be relied upon
by users of the library. Imagine, for instance, if we renamed the option
in future (with backwards compat for old configurations), then this
would mean API breakage.

So, long story short - an API along these lines makes some sense, but
especially since not having it would mean we'd need to add some way to
query the name of the transport driver.

In this commit, we add a simple new TransportURL class:

  >>> url = messaging.TransportURL.parse(cfg.CONF, 'foo:///')
  >>> str(url), url
  ('foo:///', <TransportURL transport='foo'>)
  >>> url.hosts.append(messaging.TransportHost(hostname='localhost'))
  >>> str(url), url
  ('foo://localhost/', <TransportURL transport='foo', hosts=[<TransportHost hostname='localhost'>]>)
  >>> url.transport = None
  >>> str(url), url
  ('kombu://localhost/', <TransportURL transport='kombu', hosts=[<TransportHost hostname='localhost'>]>)
  >>> cfg.CONF.set_override('rpc_backend', 'bar')
  >>> str(url), url
  ('bar://localhost/', <TransportURL transport='bar', hosts=[<TransportHost hostname='localhost'>]>)

The TransportURL.parse() method equates to parse_transport_url() and
TransportURL.__str__() equates to unparse_transport().

The transport drivers are also updated to take a TransportURL as a
required argument, which simplifies the handling of transport URLs in
the drivers.

Change-Id: Ic04173476329858e4a2c2d2707e9d4aeb212d127
This commit is contained in:
Mark McLoughlin 2013-08-12 17:16:44 +01:00
parent 5aa7c37144
commit c846cf35b8
10 changed files with 412 additions and 237 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
doc/source/transport.rst
View File

@ -8,4 +8,9 @@ Transport
.. autoclass:: Transport
.. autoclass:: TransportURL
:members:
.. autoclass:: TransportHost
.. autofunction:: set_transport_defaults

41
oslo/messaging/_drivers/amqpdriver.py
View File

@ -24,7 +24,6 @@ from oslo import messaging
from oslo.messaging._drivers import amqp as rpc_amqp
from oslo.messaging._drivers import base
from oslo.messaging._drivers import common as rpc_common
from oslo.messaging import _urls as urls
LOG = logging.getLogger(__name__)
@ -241,12 +240,12 @@ class ReplyWaiter(object):
class AMQPDriverBase(base.BaseDriver):
def __init__(self, conf, connection_pool, url=None, default_exchange=None,
allowed_remote_exmods=[]):
def __init__(self, conf, url, connection_pool,
default_exchange=None, allowed_remote_exmods=[]):
super(AMQPDriverBase, self).__init__(conf, url, default_exchange,
allowed_remote_exmods)
self._server_params = self._parse_url(self._url)
self._server_params = self._server_params_from_url(self._url)
self._default_exchange = default_exchange
@ -261,38 +260,22 @@ class AMQPDriverBase(base.BaseDriver):
self._reply_q_conn = None
self._waiter = None
@staticmethod
def _parse_url(url):
if url is None:
return None
parsed = urls.parse_url(url)
# Make sure there's not a query string; that could identify
# requirements we can't comply with (e.g., ssl), so reject it if
# it's present
if parsed['parameters']:
raise messaging.InvalidTransportURL(
url, "Cannot comply with query string in transport URL")
if not parsed['hosts']:
def _server_params_from_url(self, url):
if not url.hosts:
return None
sp = {
'virtual_host': parsed['virtual_host'],
'virtual_host': url.virtual_host,
}
# FIXME(markmc): support multiple hosts
host = parsed['hosts'][0]
host = url.hosts[0]
if ':' in host['host']:
(sp['hostname'], sp['port']) = host['host'].split(':', 1)
sp['port'] = int(sp['port'])
else:
sp['hostname'] = host['host']
sp['username'] = host['username']
sp['password'] = host['password']
sp['hostname'] = host.hostname
if host.port is not None:
sp['port'] = host.port
sp['username'] = host.username or ''
sp['password'] = host.password or ''
return sp

4
oslo/messaging/_drivers/base.py
View File

@ -55,8 +55,8 @@ class BaseDriver(object):
__metaclass__ = abc.ABCMeta
def __init__(self, conf, url=None, default_exchange=None,
allowed_remote_exmods=[]):
def __init__(self, conf, url,
default_exchange=None, allowed_remote_exmods=[]):
self.conf = conf
self._url = url
self._default_exchange = default_exchange

2
oslo/messaging/_drivers/impl_fake.py
View File

@ -86,7 +86,7 @@ class FakeExchange(object):
class FakeDriver(base.BaseDriver):
def __init__(self, conf, url=None, default_exchange=None,
def __init__(self, conf, url, default_exchange=None,
allowed_remote_exmods=[]):
super(FakeDriver, self).__init__(conf, url, default_exchange,
allowed_remote_exmods=[])

9
oslo/messaging/_drivers/impl_qpid.py
View File

@ -742,13 +742,14 @@ def cleanup():
class QpidDriver(amqpdriver.AMQPDriverBase):
def __init__(self, conf, url=None, default_exchange=None,
allowed_remote_exmods=[]):
def __init__(self, conf, url,
default_exchange=None, allowed_remote_exmods=[]):
conf.register_opts(qpid_opts)
conf.register_opts(rpc_amqp.amqp_opts)
connection_pool = rpc_amqp.get_connection_pool(conf, Connection)
super(QpidDriver, self).__init__(conf, connection_pool,
url, default_exchange,
super(QpidDriver, self).__init__(conf, url,
connection_pool,
default_exchange,
allowed_remote_exmods)

7
oslo/messaging/_drivers/impl_rabbit.py
View File

@ -873,13 +873,14 @@ def cleanup():
class RabbitDriver(amqpdriver.AMQPDriverBase):
def __init__(self, conf, url=None, default_exchange=None,
def __init__(self, conf, url, default_exchange=None,
allowed_remote_exmods=[]):
conf.register_opts(rabbit_opts)
conf.register_opts(rpc_amqp.amqp_opts)
connection_pool = rpc_amqp.get_connection_pool(conf, Connection)
super(RabbitDriver, self).__init__(conf, connection_pool,
url, default_exchange,
super(RabbitDriver, self).__init__(conf, url,
connection_pool,
default_exchange,
allowed_remote_exmods)

111
oslo/messaging/_urls.py
View File

@ -1,111 +0,0 @@
# Copyright 2013 Red Hat, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import urlparse
def parse_url(url):
"""Parse an url.
Assuming a URL takes the form of:
transport://user:pass@host1:port[,hostN:portN]/virtual_host[?opt=val]
then parse the URL and return a dictionary with the following structure:
{
'virtual_host': 'virtual_host',
'transport': 'transport',
'hosts': [{'username': 'username',
'password': 'password'
'host': 'host1:port1'},
...],
'parameters': {'option': 'value'}
}
Netloc is parsed following the sequence bellow:
* It is first splitted by ',' in order to support multiple hosts
* The last parsed username and password will be propagated to the rest
of hotsts specified:
user:passwd@host1:port1,host2:port2
[
{"username": "user", "password": "passwd", "host": "host1:port1"},
{"username": "user", "password": "passwd", "host": "host2:port2"}
]
* In order to avoid the above propagation, it is possible to alter the
order in which the hosts are specified or specify a set of fake credentials
using ",:@host2:port2"
user:passwd@host1:port1,:@host2:port2
[
{"username": "user", "password": "passwd", "host": "host1:port1"},
{"username": "", "password": "", "host": "host2:port2"}
]
:param url: The URL to parse
:type url: str
:returns: A dictionary with the parsed data
"""
if not url:
return None
# NOTE(flaper87): Not PY3K compliant
if not isinstance(url, basestring):
raise TypeError("Wrong URL type")
url = urlparse.urlparse(url)
parsed = dict(transport=url.scheme)
virtual_host = None
if url.path.startswith('/'):
virtual_host = url.path[1:]
parsed["virtual_host"] = virtual_host
# NOTE(flaper87): Parse netloc.
hosts = []
username = password = ''
for host in url.netloc.split(","):
if not host:
continue
if "@" in host:
username, host = host.split("@", 1)
if ":" in username:
username, password = username.split(":", 1)
hosts.append({
"host": host,
"username": username,
"password": password,
})
parsed["hosts"] = hosts
parameters = {}
if url.query:
# NOTE(flaper87): This returns a dict with
# key -> [value], those values need to be
# normalized
parameters = urlparse.parse_qs(url.query)
parsed['parameters'] = parameters
return parsed

252
oslo/messaging/transport.py
View File

@ -3,6 +3,7 @@
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
# Copyright 2013 Red Hat, Inc.
# Copyright (c) 2012 Rackspace Hosting
#
# 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
@ -20,10 +21,13 @@ __all__ = [
'DriverLoadFailure',
'InvalidTransportURL',
'Transport',
'TransportHost',
'TransportURL',
'get_transport',
'set_transport_defaults',
]
import urllib
import urlparse
from oslo.config import cfg
@ -136,36 +140,258 @@ def get_transport(conf, url=None, allowed_remote_exmods=[]):
rabbit://me:passwd@host:5672/virtual_host
and can either be passed as a string or a TransportURL object.
:param conf: the user configuration
:type conf: cfg.ConfigOpts
:param url: a transport URL
:type url: str
:type url: str or TransportURL
:param allowed_remote_exmods: a list of modules which a client using this
transport will deserialize remote exceptions from
transport will deserialize remote exceptions
from
:type allowed_remote_exmods: list
"""
conf.register_opts(_transport_opts)
url = url or conf.transport_url
if url is not None:
rpc_backend = urlparse.urlparse(url).scheme
if not rpc_backend:
if not isinstance(url, TransportURL):
url = url or conf.transport_url
parsed = TransportURL.parse(conf, url)
if not parsed.transport:
raise InvalidTransportURL(url, 'No scheme specified in "%s"' % url)
else:
rpc_backend = conf.rpc_backend
url = parsed
kwargs = dict(default_exchange=conf.control_exchange,
allowed_remote_exmods=allowed_remote_exmods)
if url is not None:
kwargs['url'] = url
try:
mgr = driver.DriverManager('oslo.messaging.drivers',
rpc_backend,
url.transport,
invoke_on_load=True,
invoke_args=[conf],
invoke_args=[conf, url],
invoke_kwds=kwargs)
except RuntimeError as ex:
raise DriverLoadFailure(rpc_backend, ex)
raise DriverLoadFailure(url.transport, ex)
return Transport(mgr.driver)
class TransportHost(object):
"""A host element of a parsed transport URL."""
def __init__(self, hostname=None, port=None, username=None, password=None):
self.hostname = hostname
self.port = port
self.username = username
self.password = password
def __eq__(self, other):
return vars(self) == vars(other)
def __ne__(self, other):
return not self == other
def __repr__(self):
attrs = []
for a in ['hostname', 'port', 'username', 'password']:
v = getattr(self, a)
if v:
attrs.append((a, repr(v)))
values = ', '.join(['%s=%s' % i for i in attrs])
return '<TransportHost ' + values + '>'
class TransportURL(object):
"""A parsed transport URL.
Transport URLs take the form::
transport://user:pass@host1:port[,hostN:portN]/virtual_host
i.e. the scheme selects the transport driver, you may include multiple
hosts in netloc and the path part is a "virtual host" partition path.
:param conf: a ConfigOpts instance
:type conf: oslo.config.cfg.ConfigOpts
:param transport: a transport name e.g. 'rabbit' or 'qpid'
:type transport: str
:param virtual_host: a virtual host path e.g. '/'
:type virtual_host: str
:param hosts: a list of TransportHost objects
:type hosts: list
"""
def __init__(self, conf, transport=None, virtual_host=None, hosts=None):
self.conf = conf
self.conf.register_opts(_transport_opts)
self._transport = transport
self._virtual_host = virtual_host
self._hosts = hosts
if self._hosts is None:
self._hosts = []
@property
def transport(self):
if self._transport is None:
return self.conf.rpc_backend
else:
return self._transport
@transport.setter
def transport(self, value):
self._transport = value
@property
def virtual_host(self):
return self._virtual_host
@virtual_host.setter
def virtual_host(self, value):
self._virtual_host = value
@property
def hosts(self):
return self._hosts
def __eq__(self, other):
return (self.transport == other.transport and
self.virtual_host == other.virtual_host and
self.hosts == other.hosts)
def __ne__(self, other):
return not self == other
def __repr__(self):
attrs = []
for a in ['transport', 'virtual_host', 'hosts']:
v = getattr(self, a)
if v:
attrs.append((a, repr(v)))
values = ', '.join(['%s=%s' % i for i in attrs])
return '<TransportURL ' + values + '>'
def __str__(self):
netlocs = []
for host in self.hosts:
username = host.username
password = host.password
hostname = host.hostname
port = host.port
# Starting place for the network location
netloc = ''
# Build the username and password portion of the transport URL
if username is not None or password is not None:
if username is not None:
netloc += urllib.quote(username, '')
if password is not None:
netloc += ':%s' % urllib.quote(password, '')
netloc += '@'
# Build the network location portion of the transport URL
if hostname:
if ':' in hostname:
netloc += '[%s]' % hostname
else:
netloc += hostname
if port is not None:
netloc += ':%d' % port
netlocs.append(netloc)
# Assemble the transport URL
url = '%s://%s/' % (self.transport, ','.join(netlocs))
if self.virtual_host:
url += urllib.quote(self.virtual_host)
return url
@classmethod
def parse(cls, conf, url):
"""Parse an url.
Assuming a URL takes the form of:
transport://user:pass@host1:port[,hostN:portN]/virtual_host
then parse the URL and return a TransportURL object.
Netloc is parsed following the sequence bellow:
* It is first splitted by ',' in order to support multiple hosts
* The last parsed username and password will be propagated to the rest
of hotsts specified:
user:passwd@host1:port1,host2:port2
[
{"username": "user", "password": "passwd", "host": "host1:port1"},
{"username": "user", "password": "passwd", "host": "host2:port2"}
]
* In order to avoid the above propagation, it is possible to alter the
order in which the hosts are specified or specify a set of fake
credentials using ",:@host2:port2"
user:passwd@host1:port1,:@host2:port2
[
{"username": "user", "password": "passwd", "host": "host1:port1"},
{"username": "", "password": "", "host": "host2:port2"}
]
:param conf: a ConfigOpts instance
:type conf: oslo.config.cfg.ConfigOpts
:param url: The URL to parse
:type url: str
:returns: A TransportURL
"""
if not url:
return cls(conf)
# FIXME(flaper87): Not PY3K compliant
if not isinstance(url, basestring):
raise InvalidTransportURL(url, 'Wrong URL type')
url = urlparse.urlparse(url)
# Make sure there's not a query string; that could identify
# requirements we can't comply with (e.g., ssl), so reject it if
# it's present
if '?' in url.path or url.query:
raise InvalidTransportURL(url.geturl(),
"Cannot comply with query string in "
"transport URL")
virtual_host = None
if url.path.startswith('/'):
virtual_host = url.path[1:]
hosts = []
username = password = ''
for host in url.netloc.split(','):
if not host:
continue
hostname = host
username = password = port = None
if '@' in host:
username, hostname = host.split('@', 1)
if ':' in username:
username, password = username.split(':', 1)
if ':' in hostname:
hostname, port = hostname.split(':', 1)
port = int(port)
hosts.append(TransportHost(hostname=hostname,
port=port,
username=username,
password=password))
return cls(conf, url.scheme, virtual_host, hosts)

41
tests/test_transport.py
View File

@ -52,26 +52,12 @@ class _FakeManager(object):
class GetTransportTestCase(test_utils.BaseTestCase):
scenarios = [
('all_none',
dict(url=None, transport_url=None, rpc_backend=None,
control_exchange=None, allowed=None,
expect=dict(backend=None,
exchange=None,
url=None,
allowed=[]))),
('rpc_backend',
dict(url=None, transport_url=None, rpc_backend='testbackend',
control_exchange=None, allowed=None,
expect=dict(backend='testbackend',
exchange=None,
url=None,
allowed=[]))),
('control_exchange',
dict(url=None, transport_url=None, rpc_backend=None,
control_exchange='testexchange', allowed=None,
expect=dict(backend=None,
exchange='testexchange',
url=None,
url='testbackend:',
allowed=[]))),
('transport_url',
dict(url=None, transport_url='testtransport:', rpc_backend=None,
@ -87,12 +73,19 @@ class GetTransportTestCase(test_utils.BaseTestCase):
exchange=None,
url='testtransport:',
allowed=[]))),
('control_exchange',
dict(url=None, transport_url=None, rpc_backend='testbackend',
control_exchange='testexchange', allowed=None,
expect=dict(backend='testbackend',
exchange='testexchange',
url='testbackend:',
allowed=[]))),
('allowed_remote_exmods',
dict(url=None, transport_url=None, rpc_backend=None,
dict(url=None, transport_url=None, rpc_backend='testbackend',
control_exchange=None, allowed=['foo', 'bar'],
expect=dict(backend=None,
expect=dict(backend='testbackend',
exchange=None,
url=None,
url='testbackend:',
allowed=['foo', 'bar']))),
]
@ -107,11 +100,11 @@ class GetTransportTestCase(test_utils.BaseTestCase):
self.mox.StubOutWithMock(driver, 'DriverManager')
invoke_args = [self.conf]
invoke_args = [self.conf,
messaging.TransportURL.parse(self.conf,
self.expect['url'])]
invoke_kwds = dict(default_exchange=self.expect['exchange'],
allowed_remote_exmods=self.expect['allowed'])
if self.expect['url']:
invoke_kwds['url'] = self.expect['url']
drvr = _FakeDriver(self.conf)
driver.DriverManager('oslo.messaging.drivers',
@ -164,7 +157,9 @@ class GetTransportSadPathTestCase(test_utils.BaseTestCase):
if self.rpc_backend:
self.mox.StubOutWithMock(driver, 'DriverManager')
invoke_args = [self.conf]
invoke_args = [self.conf,
messaging.TransportURL.parse(self.conf,
self.url)]
invoke_kwds = dict(default_exchange='openstack',
allowed_remote_exmods=[])
@ -191,7 +186,7 @@ class GetTransportSadPathTestCase(test_utils.BaseTestCase):
for k, v in self.ex.items():
self.assertTrue(hasattr(ex, k))
self.assertEqual(getattr(ex, k), v)
self.assertEqual(str(getattr(ex, k)), v)
# FIXME(markmc): this could be used elsewhere

177
tests/test_urls.py
View File

@ -13,12 +13,13 @@
# License for the specific language governing permissions and limitations
# under the License.
from oslo.config import cfg
import testscenarios
from oslo.messaging import _urls as urls
from oslo import messaging
from oslo.messaging import transport
from tests import utils as test_utils
load_tests = testscenarios.load_tests_apply_scenarios
@ -27,89 +28,163 @@ class TestParseURL(test_utils.BaseTestCase):
scenarios = [
('transport',
dict(url='foo:',
expect=dict(transport='foo',
virtual_host=None,
hosts=[],
parameters={}))),
expect=dict(transport='foo'))),
('virtual_host_slash',
dict(url='foo:////',
expect=dict(transport='foo',
virtual_host='/',
hosts=[],
parameters={}))),
expect=dict(transport='foo', virtual_host='/'))),
('virtual_host',
dict(url='foo:///bar',
expect=dict(transport='foo',
virtual_host='bar',
hosts=[],
parameters={}))),
expect=dict(transport='foo', virtual_host='bar'))),
('host',
dict(url='foo://host/bar',
expect=dict(transport='foo',
virtual_host='bar',
hosts=[
dict(host='host',
username='',
password=''),
],
parameters={}))),
dict(host='host'),
]))),
('port',
dict(url='foo://host:1234/bar',
expect=dict(transport='foo',
virtual_host='bar',
hosts=[
dict(host='host:1234',
username='',
password=''),
],
parameters={}))),
dict(host='host', port=1234),
]))),
('username',
dict(url='foo://u@host:1234/bar',
expect=dict(transport='foo',
virtual_host='bar',
hosts=[
dict(host='host:1234',
username='u',
password=''),
],
parameters={}))),
dict(host='host', port=1234, username='u'),
]))),
('password',
dict(url='foo://u:p@host:1234/bar',
expect=dict(transport='foo',
virtual_host='bar',
hosts=[
dict(host='host:1234',
username='u',
password='p'),
],
parameters={}))),
dict(host='host', port=1234,
username='u', password='p'),
]))),
('multi_host',
dict(url='foo://u:p@host1:1234,host2:4321/bar',
expect=dict(transport='foo',
virtual_host='bar',
hosts=[
dict(host='host1:1234',
username='u',
password='p'),
dict(host='host2:4321',
username='u',
password='p'),
],
parameters={}))),
dict(host='host1', port=1234,
username='u', password='p'),
dict(host='host2', port=4321),
]))),
('multi_creds',
dict(url='foo://u1:p1@host1:1234,u2:p2@host2:4321/bar',
expect=dict(transport='foo',
virtual_host='bar',
hosts=[
dict(host='host1:1234',
username='u1',
password='p1'),
dict(host='host2:4321',
username='u2',
password='p2'),
],
parameters={}))),
dict(host='host1', port=1234,
username='u1', password='p1'),
dict(host='host2', port=4321,
username='u2', password='p2'),
]))),
]
def setUp(self):
super(TestParseURL, self).setUp(conf=cfg.ConfigOpts())
self.conf.register_opts(transport._transport_opts)
def test_parse_url(self):
self.assertEqual(urls.parse_url(self.url), self.expect)
self.config(rpc_backend=None)
url = messaging.TransportURL.parse(self.conf, self.url)
hosts = []
for host in self.expect.get('hosts', []):
hosts.append(messaging.TransportHost(host.get('host'),
host.get('port'),
host.get('username'),
host.get('password')))
expected = messaging.TransportURL(self.conf,
self.expect.get('transport'),
self.expect.get('virtual_host'),
hosts)
self.assertEqual(url, expected)
class TestFormatURL(test_utils.BaseTestCase):
scenarios = [
('rpc_backend',
dict(rpc_backend='testbackend',
transport=None,
virtual_host=None,
hosts=[],
expected='testbackend:///')),
('transport',
dict(rpc_backend=None,
transport='testtransport',
virtual_host=None,
hosts=[],
expected='testtransport:///')),
('virtual_host',
dict(rpc_backend=None,
transport='testtransport',
virtual_host='/vhost',
hosts=[],
expected='testtransport:////vhost')),
('host',
dict(rpc_backend=None,
transport='testtransport',
virtual_host='/',
hosts=[
dict(hostname='host',
port=10,
username='bob',
password='secret'),
],
expected='testtransport://bob:secret@host:10//')),
('multi_host',
dict(rpc_backend=None,
transport='testtransport',
virtual_host='',
hosts=[
dict(hostname='h1',
port=1000,
username='b1',
password='s1'),
dict(hostname='h2',
port=2000,
username='b2',
password='s2'),
],
expected='testtransport://b1:s1@h1:1000,b2:s2@h2:2000/')),
('quoting',
dict(rpc_backend=None,
transport='testtransport',
virtual_host='/$',
hosts=[
dict(hostname='host',
port=10,
username='b$',
password='s&'),
],
expected='testtransport://b%24:s%26@host:10//%24')),
]
def setUp(self):
super(TestFormatURL, self).setUp(conf=cfg.ConfigOpts())
self.conf.register_opts(transport._transport_opts)
def test_parse_url(self):
self.config(rpc_backend=self.rpc_backend)
hosts = []
for host in self.hosts:
hosts.append(messaging.TransportHost(host.get('hostname'),
host.get('port'),
host.get('username'),
host.get('password')))
url = messaging.TransportURL(self.conf,
self.transport,
self.virtual_host,
hosts)
self.assertEqual(str(url), self.expected)