no_declare option added to Queue/Exchange (also enabled for internal amq. exchanges). Closes #565

kombu/entity.py

@@ -21,6 +21,8 @@ DELIVERY_MODES = {'transient': TRANSIENT_DELIVERY_MODE,
 
 __all__ = ['Exchange', 'Queue', 'binding', 'maybe_delivery_mode']
 
+INTERNAL_EXCHANGE_PREFIX = ('amq.',)
+
 
 def _reprstr(s):
     s = repr(s)
@@ -50,6 +52,7 @@ class Exchange(MaybeChannelBound):
     :keyword auto_delete: See :attr:`auto_delete`.
     :keyword delivery_mode: See :attr:`delivery_mode`.
     :keyword arguments: See :attr:`arguments`.
+    :keyword no_declare: See :attr:`no_declare`
 
     .. attribute:: name
 
@@ -136,6 +139,10 @@ class Exchange(MaybeChannelBound):
 
         Additional arguments to specify when the exchange is declared.
 
+    .. attribute:: no_declare
+
+        Never declare this exchange (:meth:`declare` does nothing).
+
     """
     TRANSIENT_DELIVERY_MODE = TRANSIENT_DELIVERY_MODE
     PERSISTENT_DELIVERY_MODE = PERSISTENT_DELIVERY_MODE
@@ -146,6 +153,7 @@ class Exchange(MaybeChannelBound):
     auto_delete = False
     passive = False
     delivery_mode = None
+    no_declare = False
 
     attrs = (
         ('name', None),
@@ -155,6 +163,7 @@ class Exchange(MaybeChannelBound):
         ('passive', bool),
         ('auto_delete', bool),
         ('delivery_mode', lambda m: DELIVERY_MODES.get(m) or m),
+        ('no_declare', bool),
     )
 
     def __init__(self, name='', type='', channel=None, **kwargs):
@@ -166,6 +175,11 @@ class Exchange(MaybeChannelBound):
     def __hash__(self):
         return hash('E|%s' % (self.name,))
 
+    def _can_declare(self):
+        return not self.no_declare and (
+                self.name and not self.name.startswith(
+                    INTERNAL_EXCHANGE_PREFIX))
+
     def declare(self, nowait=False, passive=None):
         """Declare the exchange.
 
@@ -175,8 +189,8 @@ class Exchange(MaybeChannelBound):
             response will not be waited for. Default is :const:`False`.
 
         """
-        passive = self.passive if passive is None else passive
-        if self.name:
+        if self._can_declare():
+            passive = self.passive if passive is None else passive
             return self.channel.exchange_declare(
                 exchange=self.name, type=self.type, durable=self.durable,
                 auto_delete=self.auto_delete, arguments=self.arguments,
@@ -373,6 +387,7 @@ class Queue(MaybeChannelBound):
     :keyword queue_arguments: See :attr:`queue_arguments`.
     :keyword binding_arguments: See :attr:`binding_arguments`.
     :keyword consumer_arguments: See :attr:`consumer_arguments`.
+    :keyword no_declare: See :attr:`no_declare`
     :keyword on_declared: See :attr:`on_declared`
 
     .. attribute:: name
@@ -472,6 +487,11 @@ class Queue(MaybeChannelBound):
         This must be a function with a signature that accepts at least 3
         positional arguments: ``(name, messages, consumers)``.
 
+    .. attribute:: no_declare
+
+        Never declare this queue, nor related entities (:meth:`declare` does
+        nothing).
+
     """
     ContentDisallowed = ContentDisallowed
 
@@ -497,6 +517,7 @@ class Queue(MaybeChannelBound):
         ('no_ack', None),
         ('alias', None),
         ('bindings', list),
+        ('no_declare', bool),
     )
 
     def __init__(self, name='', exchange=None, routing_key='',
@@ -536,19 +557,26 @@ class Queue(MaybeChannelBound):
     def declare(self, nowait=False):
         """Declares the queue, the exchange and binds the queue to
         the exchange."""
-        # - declare main binding.
+        if not self.no_declare:
+            # - declare main binding.
+            self._create_exchange(nowait=nowait)
+            self._create_queue(nowait=nowait)
+            self._create_bindings(nowait=nowait)
+        return self.name
+
+    def _create_exchange(self, nowait=False):
         if self.exchange:
             self.exchange.declare(nowait)
-        self.queue_declare(nowait, passive=False)
 
+    def _create_queue(self, nowait=False):
+        self.queue_declare(nowait, passive=False)
         if self.exchange and self.exchange.name:
             self.queue_bind(nowait)
 
-        # - declare extra/multi-bindings.
+    def _create_bindings(self, nowait=False):
         for B in self.bindings:
             B.declare(self.channel)
             B.bind(self, nowait=nowait)
-        return self.name
 
     def queue_declare(self, nowait=False, passive=False):
         """Declare queue on the server.

kombu/tests/test_entities.py

@@ -190,6 +190,24 @@ class test_Exchange(Case):
         foo(chan).unbind_from('bar')
         self.assertIn('exchange_unbind', chan)
 
+    def test_declare__no_declare(self):
+        chan = get_conn().channel()
+        foo = Exchange('foo', 'topic', no_declare=True)
+        foo(chan).declare()
+        self.assertNotIn('exchange_declare', chan)
+
+    def test_declare__internal_exchange(self):
+        chan = get_conn().channel()
+        foo = Exchange('amq.rabbitmq.trace', 'topic')
+        foo(chan).declare()
+        self.assertNotIn('exchange_declare', chan)
+
+    def test_declare(self):
+        chan = get_conn().channel()
+        foo = Exchange('foo', 'topic', no_declare=False)
+        foo(chan).declare()
+        self.assertIn('exchange_declare', chan)
+
 
 class test_Queue(Case):
 
@@ -257,6 +275,16 @@ class test_Queue(Case):
         q.declare()
         q.queue_declare.assert_called_with(False, passive=False)
 
+    def test_declare__no_declare(self):
+        q = Queue('a', no_declare=True)
+        q.queue_declare = Mock()
+        q.queue_bind = Mock()
+        q.exchange = None
+
+        q.declare()
+        self.assertFalse(q.queue_declare.called)
+        self.assertFalse(q.queue_bind.called)
+
     def test_bind_to_when_name(self):
         chan = Mock()
         q = Queue('a')