5bd31315c2
In commit d8d2ad9 we added support for notification listener endpoint methods to return REQUEUE, but if a driver does not support this we raise NotImplementedError when the application attempts to requeue a message. This requeuing behaviour might only be used by an application in unusual, exceptional circumstances and catch users by surprise. Instead, let's require the application to assert that it needs this feature in advance and raise NotImplementError at that point if the driver doesn't support it. Change-Id: Id0bb0e57d2dcc1ec7d752e98c9b1e8e48d99f35c
427 lines
14 KiB
Python
427 lines
14 KiB
Python
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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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# All Rights Reserved.
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# Copyright 2013 Red Hat, Inc.
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# Copyright (c) 2012 Rackspace Hosting
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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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__all__ = [
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'DriverLoadFailure',
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'InvalidTransportURL',
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'Transport',
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'TransportHost',
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'TransportURL',
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'get_transport',
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'set_transport_defaults',
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]
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from oslo.config import cfg
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import six
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from stevedore import driver
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from oslo.messaging import exceptions
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from oslo.messaging.openstack.common.py3kcompat import urlutils
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_transport_opts = [
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cfg.StrOpt('transport_url',
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default=None,
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help='A URL representing the messaging driver to use and its '
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'full configuration. If not set, we fall back to the '
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'rpc_backend option and driver specific configuration.'),
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cfg.StrOpt('rpc_backend',
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default='rabbit',
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help='The messaging driver to use, defaults to rabbit. Other '
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'drivers include qpid and zmq.'),
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cfg.StrOpt('control_exchange',
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default='openstack',
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help='The default exchange under which topics are scoped. May '
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'be overridden by an exchange name specified in the '
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'transport_url option.'),
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]
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def set_transport_defaults(control_exchange):
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"""Set defaults for messaging transport configuration options.
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:param control_exchange: the default exchange under which topics are scoped
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:type control_exchange: str
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"""
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cfg.set_defaults(_transport_opts,
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control_exchange=control_exchange)
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class Transport(object):
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"""A messaging transport.
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This is a mostly opaque handle for an underlying messaging transport
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driver.
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It has a single 'conf' property which is the cfg.ConfigOpts instance used
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to construct the transport object.
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"""
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def __init__(self, driver):
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self.conf = driver.conf
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self._driver = driver
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def _require_driver_features(self, requeue=False):
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self._driver.require_features(requeue=requeue)
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def _send(self, target, ctxt, message, wait_for_reply=None, timeout=None):
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if not target.topic:
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raise exceptions.InvalidTarget('A topic is required to send',
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target)
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return self._driver.send(target, ctxt, message,
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wait_for_reply=wait_for_reply,
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timeout=timeout)
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def _send_notification(self, target, ctxt, message, version):
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if not target.topic:
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raise exceptions.InvalidTarget('A topic is required to send',
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target)
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self._driver.send_notification(target, ctxt, message, version)
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def _listen(self, target):
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if not (target.topic and target.server):
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raise exceptions.InvalidTarget('A server\'s target must have '
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'topic and server names specified',
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target)
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return self._driver.listen(target)
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def _listen_for_notifications(self, targets_and_priorities):
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for target, priority in targets_and_priorities:
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if not target.topic:
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raise exceptions.InvalidTarget('A target must have '
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'topic specified',
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target)
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return self._driver.listen_for_notifications(targets_and_priorities)
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def cleanup(self):
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"""Release all resources associated with this transport."""
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self._driver.cleanup()
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class InvalidTransportURL(exceptions.MessagingException):
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"""Raised if transport URL is invalid."""
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def __init__(self, url, msg):
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super(InvalidTransportURL, self).__init__(msg)
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self.url = url
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class DriverLoadFailure(exceptions.MessagingException):
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"""Raised if a transport driver can't be loaded."""
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def __init__(self, driver, ex):
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msg = 'Failed to load transport driver "%s": %s' % (driver, ex)
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super(DriverLoadFailure, self).__init__(msg)
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self.driver = driver
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self.ex = ex
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def get_transport(conf, url=None, allowed_remote_exmods=[], aliases=None):
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"""A factory method for Transport objects.
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This method will construct a Transport object from transport configuration
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gleaned from the user's configuration and, optionally, a transport URL.
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If a transport URL is supplied as a parameter, any transport configuration
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contained in it takes precedence. If no transport URL is supplied, but
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there is a transport URL supplied in the user's configuration then that
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URL will take the place of the URL parameter. In both cases, any
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configuration not supplied in the transport URL may be taken from
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individual configuration parameters in the user's configuration.
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An example transport URL might be::
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rabbit://me:passwd@host:5672/virtual_host
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and can either be passed as a string or a TransportURL object.
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:param conf: the user configuration
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:type conf: cfg.ConfigOpts
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:param url: a transport URL
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:type url: str or TransportURL
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:param allowed_remote_exmods: a list of modules which a client using this
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transport will deserialize remote exceptions
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from
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:type allowed_remote_exmods: list
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:param aliases: A map of transport alias to transport name
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:type aliases: dict
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"""
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conf.register_opts(_transport_opts)
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if not isinstance(url, TransportURL):
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url = url or conf.transport_url
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parsed = TransportURL.parse(conf, url, aliases)
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if not parsed.transport:
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raise InvalidTransportURL(url, 'No scheme specified in "%s"' % url)
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url = parsed
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kwargs = dict(default_exchange=conf.control_exchange,
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allowed_remote_exmods=allowed_remote_exmods)
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try:
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mgr = driver.DriverManager('oslo.messaging.drivers',
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url.transport,
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invoke_on_load=True,
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invoke_args=[conf, url],
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invoke_kwds=kwargs)
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except RuntimeError as ex:
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raise DriverLoadFailure(url.transport, ex)
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return Transport(mgr.driver)
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class TransportHost(object):
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"""A host element of a parsed transport URL."""
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def __init__(self, hostname=None, port=None, username=None, password=None):
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self.hostname = hostname
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self.port = port
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self.username = username
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self.password = password
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def __eq__(self, other):
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return vars(self) == vars(other)
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def __ne__(self, other):
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return not self == other
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def __repr__(self):
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attrs = []
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for a in ['hostname', 'port', 'username', 'password']:
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v = getattr(self, a)
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if v:
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attrs.append((a, repr(v)))
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values = ', '.join(['%s=%s' % i for i in attrs])
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return '<TransportHost ' + values + '>'
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class TransportURL(object):
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"""A parsed transport URL.
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Transport URLs take the form::
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transport://user:pass@host1:port[,hostN:portN]/virtual_host
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i.e. the scheme selects the transport driver, you may include multiple
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hosts in netloc and the path part is a "virtual host" partition path.
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:param conf: a ConfigOpts instance
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:type conf: oslo.config.cfg.ConfigOpts
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:param transport: a transport name e.g. 'rabbit' or 'qpid'
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:type transport: str
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:param virtual_host: a virtual host path e.g. '/'
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:type virtual_host: str
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:param hosts: a list of TransportHost objects
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:type hosts: list
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:param aliases: A map of transport alias to transport name
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:type aliases: dict
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"""
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def __init__(self, conf, transport=None, virtual_host=None, hosts=None,
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aliases=None):
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self.conf = conf
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self.conf.register_opts(_transport_opts)
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self._transport = transport
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self.virtual_host = virtual_host
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if hosts is None:
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self.hosts = []
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else:
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self.hosts = hosts
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if aliases is None:
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self.aliases = {}
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else:
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self.aliases = aliases
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@property
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def transport(self):
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if self._transport is None:
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transport = self.conf.rpc_backend
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else:
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transport = self._transport
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return self.aliases.get(transport, transport)
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@transport.setter
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def transport(self, value):
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self._transport = value
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def __eq__(self, other):
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return (self.transport == other.transport and
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self.virtual_host == other.virtual_host and
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self.hosts == other.hosts)
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def __ne__(self, other):
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return not self == other
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def __repr__(self):
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attrs = []
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for a in ['transport', 'virtual_host', 'hosts']:
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v = getattr(self, a)
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if v:
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attrs.append((a, repr(v)))
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values = ', '.join(['%s=%s' % i for i in attrs])
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return '<TransportURL ' + values + '>'
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def __str__(self):
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netlocs = []
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for host in self.hosts:
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username = host.username
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password = host.password
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hostname = host.hostname
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port = host.port
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# Starting place for the network location
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netloc = ''
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# Build the username and password portion of the transport URL
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if username is not None or password is not None:
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if username is not None:
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netloc += urlutils.quote(username, '')
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if password is not None:
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netloc += ':%s' % urlutils.quote(password, '')
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netloc += '@'
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# Build the network location portion of the transport URL
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if hostname:
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if ':' in hostname:
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netloc += '[%s]' % hostname
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else:
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netloc += hostname
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if port is not None:
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netloc += ':%d' % port
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netlocs.append(netloc)
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# Assemble the transport URL
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url = '%s://%s/' % (self.transport, ','.join(netlocs))
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if self.virtual_host:
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url += urlutils.quote(self.virtual_host)
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return url
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@classmethod
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def parse(cls, conf, url, aliases=None):
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"""Parse an url.
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Assuming a URL takes the form of:
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transport://user:pass@host1:port[,hostN:portN]/virtual_host
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then parse the URL and return a TransportURL object.
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Netloc is parsed following the sequence bellow:
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* It is first split by ',' in order to support multiple hosts
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* The last parsed username and password will be propagated to the rest
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of hosts specified:
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user:passwd@host1:port1,host2:port2
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[
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{"username": "user", "password": "passwd", "host": "host1:port1"},
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{"username": "user", "password": "passwd", "host": "host2:port2"}
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]
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* In order to avoid the above propagation, it is possible to alter the
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order in which the hosts are specified or specify a set of fake
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credentials using ",:@host2:port2"
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user:passwd@host1:port1,:@host2:port2
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[
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{"username": "user", "password": "passwd", "host": "host1:port1"},
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{"username": "", "password": "", "host": "host2:port2"}
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]
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:param conf: a ConfigOpts instance
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:type conf: oslo.config.cfg.ConfigOpts
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:param url: The URL to parse
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:type url: str
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:param aliases: A map of transport alias to transport name
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:type aliases: dict
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:returns: A TransportURL
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"""
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if not url:
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return cls(conf, aliases=aliases)
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if not isinstance(url, six.string_types):
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raise InvalidTransportURL(url, 'Wrong URL type')
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url = urlutils.urlparse(url)
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# Make sure there's not a query string; that could identify
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# requirements we can't comply with (e.g., ssl), so reject it if
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# it's present
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if '?' in url.path or url.query:
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raise InvalidTransportURL(url.geturl(),
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"Cannot comply with query string in "
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"transport URL")
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virtual_host = None
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if url.path.startswith('/'):
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virtual_host = url.path[1:]
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hosts = []
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username = password = ''
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for host in url.netloc.split(','):
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if not host:
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continue
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hostname = host
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username = password = port = None
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if '@' in host:
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username, hostname = host.split('@', 1)
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if ':' in username:
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username, password = username.split(':', 1)
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if not hostname:
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hostname = None
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elif hostname.startswith('['):
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# Find the closing ']' and extract the hostname
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host_end = hostname.find(']')
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if host_end < 0:
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# NOTE(Vek): Identical to what Python 2.7's
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# urlparse.urlparse() raises in this case
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raise ValueError("Invalid IPv6 URL")
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port_text = hostname[host_end:]
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hostname = hostname[1:host_end]
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# Now we need the port; this is compliant with how urlparse
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# parses the port data
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port = None
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if ':' in port_text:
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port = int(port_text.split(':', 1)[1])
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elif ':' in hostname:
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hostname, port = hostname.split(':', 1)
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port = int(port)
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hosts.append(TransportHost(hostname=hostname,
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port=port,
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username=username,
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password=password))
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return cls(conf, url.scheme, virtual_host, hosts, aliases)
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