Deprecate oslo.messaging rpc_backend option parameter

Oslo.messaging uses the transport_url to represent the rpc and
notification messaging driver to use and its full configuration. The
rpc_backend configuration option is deprecated for removal and
should not gate oslo.messaging driver configuration options.

This patch:
* deprecate rpc_backend
* remove conditional check
* update spec tests
* add release note

Change-Id: I071912e15a2e98f523b0888f9f4f20b9ed94e4d9

manifests/init.pp

@@ -116,10 +116,6 @@
 #      transport://user:pass@host1:port[,hostN:portN]/virtual_host
 #    Defaults to $::os_service_default
 #
-# [*rpc_backend*]
-#   (optional) what rpc/queuing service to use
-#   Defaults to $::os_service_default
-#
 # [*rpc_response_timeout*]
 #   (optional) Seconds to wait for a response from a call
 #   Defaults to $::os_service_default
@@ -352,6 +348,10 @@
 #   multiple RabbitMQ Brokers.
 #   Defaults to $::os_service_default
 #
+# [*rpc_backend*]
+#   (optional) what rpc/queuing service to use
+#   Defaults to $::os_service_default
+#
 class neutron (
   $enabled                              = true,
   $package_ensure                       = 'present',
@@ -376,7 +376,6 @@ class neutron (
   $report_interval                      = $::os_service_default,
   $control_exchange                     = 'neutron',
   $default_transport_url                = $::os_service_default,
-  $rpc_backend                          = $::os_service_default,
   $rpc_response_timeout                 = $::os_service_default,
   $rabbit_ha_queues                     = $::os_service_default,
   $rabbit_heartbeat_timeout_threshold   = $::os_service_default,
@@ -430,6 +429,7 @@ class neutron (
   $rabbit_port                          = $::os_service_default,
   $rabbit_user                          = $::os_service_default,
   $rabbit_virtual_host                  = $::os_service_default,
+  $rpc_backend                          = $::os_service_default,
 ) {
 
   include ::neutron::deps
@@ -467,10 +467,12 @@ class neutron (
     !is_service_default($rabbit_password) or
     !is_service_default($rabbit_port) or
     !is_service_default($rabbit_user) or
-    !is_service_default($rabbit_virtual_host) {
+    !is_service_default($rabbit_virtual_host) or
+    !is_service_default($rpc_backend) {
     warning("neutron::rabbit_host, neutron::rabbit_hosts, neutron::rabbit_password, \
-neutron::rabbit_port, neutron::rabbit_user and neutron::rabbit_virtual_host are \
+neutron::rabbit_port, neutron::rabbit_user, neutron::rabbit_virtual_host and \
-deprecated. Please use neutron::default_transport_url instead.")
+neutron::rpc_backend are deprecated. Please use neutron::default_transport_url \
+instead.")
   }
 
   package { 'neutron':
@@ -526,11 +528,6 @@ deprecated. Please use neutron::default_transport_url instead.")
     }
   }
 
-  if $rpc_backend in [$::os_service_default, 'rabbit'] {
-    if is_service_default($default_transport_url) and is_service_default($rabbit_password) {
-      fail('When rpc_backend is rabbitmq, you must set rabbit password')
-    }
-
   oslo::messaging::rabbit {'neutron_config':
     rabbit_userid                        => $rabbit_user,
     rabbit_password                      => $rabbit_password,
@@ -553,7 +550,7 @@ deprecated. Please use neutron::default_transport_url instead.")
     rabbit_port                          => $rabbit_port,
     kombu_ssl_version                    => $kombu_ssl_version,
   }
-  } elsif $rpc_backend == 'amqp' {
+
   oslo::messaging::amqp { 'neutron_config':
     server_request_prefix  => $amqp_server_request_prefix,
     broadcast_prefix       => $amqp_broadcast_prefix,
@@ -572,11 +569,6 @@ deprecated. Please use neutron::default_transport_url instead.")
     username               => $amqp_username,
     password               => $amqp_password,
   }
-  } else {
-    neutron_config {
-      'DEFAULT/rpc_backend': value => $rpc_backend;
-    }
-  }
 
   # SSL Options
   neutron_config {

releasenotes/notes/deprecate_rpc_backend_parameter-3387dac8e395c003.yaml

@@ -0,0 +1,4 @@
+---
+deprecations:
+  - neutron::rpc_backend is deprecated and will be removed in a future
+    release. Please use neutron::default_transport_url instead.

spec/classes/neutron_init_spec.rb

@@ -92,7 +92,7 @@ describe 'neutron' do
     it_configures 'with transport_url defined'
     it_configures 'with rootwrap daemon'
 
-    context 'with amqp rpc_backend value' do
+    context 'with amqp messaging' do
       it_configures 'amqp support'
     end
   end
@@ -472,9 +472,7 @@ describe 'neutron' do
   end
 
   shared_examples_for 'amqp support' do
-    context 'with default parameters' do
+    context 'with default amqp parameters' do
-      before { params.merge!( :rpc_backend => 'amqp' ) }
-
       it { is_expected.to contain_neutron_config('oslo_messaging_amqp/server_request_prefix').with_value('<SERVICE DEFAULT>') }
       it { is_expected.to contain_neutron_config('oslo_messaging_amqp/broadcast_prefix').with_value('<SERVICE DEFAULT>') }
       it { is_expected.to contain_neutron_config('oslo_messaging_amqp/group_request_prefix').with_value('<SERVICE DEFAULT>') }
@@ -495,7 +493,6 @@ describe 'neutron' do
 
     context 'with overriden amqp parameters' do
       before { params.merge!(
-        :rpc_backend        => 'amqp',
         :amqp_idle_timeout  => '60',
         :amqp_trace         => true,
         :amqp_ssl_ca_file   => '/path/to/ca.cert',