Merge "Fix nova deployment failure when rabbitmq is disabled"

ansible/roles/nova-cell/tasks/rabbitmq.yml

@@ -24,4 +24,6 @@
         - nova_cell_rpc_group_name != nova_cell_notify_group_name or
           nova_cell_rpc_rabbitmq_users != nova_cell_notify_rabbitmq_users
 
-  when: nova_cell_rpc_transport == 'rabbit'
+  when:
+    - nova_cell_rpc_transport == 'rabbit'
+    - enable_rabbitmq | bool

doc/source/reference/message-queues/external-rabbitmq-guide.rst

@@ -0,0 +1,53 @@
+.. _external-rabbitmq-guide:
+
+=================
+External RabbitMQ
+=================
+
+Sometimes, for various reasons (Redundancy, organisational policies, etc.),
+it might be necessary to use an external RabbitMQ cluster.
+This use case can be achieved with the following steps:
+
+Requirements
+~~~~~~~~~~~~
+
+* An existing RabbitMQ cluster, reachable from all of your
+  nodes.
+
+Enabling External RabbitMQ support
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In order to enable external RabbitMQ support,
+you will first need to disable RabbitMQ deployment,
+by ensuring the following line exists within ``/etc/kolla/globals.yml`` :
+
+.. code-block:: yaml
+
+   enable_rabbitmq: "no"
+
+
+Overwriting transport_url within ``globals.yml``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When you use an external RabbitMQ cluster, you must overwrite
+``*_transport_url`` within ``/etc/kolla/globals.yml``
+
+.. code-block:: yaml
+
+   rpc_transport_url:
+   notify_transport_url:
+   nova_cell_rpc_transport_url:
+   nova_cell_notify_transport_url:
+
+For example:
+
+.. code-block:: yaml
+
+   rpc_transport_url: rabbit://openstack:6Y6Eh3blPXB1Qn4190JKxRoyVhTaFsY2k2V0DuIc@10.0.0.1:5672,openstack:6Y6Eh3blPXB1Qn4190JKxRoyVhTaFsY2k2V0DuIc@10.0.0.2:5672,openstack:6Y6Eh3blPXB1Qn4190JKxRoyVhTaFsY2k2V0DuIc@10.0.0.3:5672//
+   notify_transport_url: "{{ rpc_transport_url }}"
+   nova_cell_rpc_transport_url: rabbit://openstack:6Y6Eh3blPXB1Qn4190JKxRoyVhTaFsY2k2V0DuIc@10.0.0.1:5672//
+   nova_cell_notify_transport_url: "{{ nova_cell_rpc_transport_url }}"
+
+.. note::
+
+   Ensure the rabbitmq user used in ``*_transport_url`` exists.

doc/source/reference/message-queues/index.rst

@@ -8,3 +8,4 @@ This section describes configuration of message queue services.
    :maxdepth: 1
 
    rabbitmq
+   external-rabbitmq-guide