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: I1537c9e0db956d4271c8334a0aa543cd20c57e67

manifests/init.pp

@@ -29,10 +29,6 @@
 #   option.
 #   Defaults to $::os_service_default
 #
-# [*rpc_backend*]
-#   (Optional) Use these options to configure the message system.
-#   Defaults to $::os_service_default.
-#
 # [*rpc_response_timeout*]
 #   (Optional) Configure the timeout (in seconds) for rpc responses
 #   Defaults to $::os_service_default.
@@ -317,13 +313,16 @@
 #   (Optional) Virtual_host to use.
 #   Defaults to $::os_service_default.
 #
+# [*rpc_backend*]
+#   (Optional) Use these options to configure the message system.
+#   Defaults to $::os_service_default.
+#
 class heat(
   $package_ensure                     = 'present',
   $debug                              = undef,
   $log_dir                            = undef,
   $keystone_ec2_uri                   = 'http://127.0.0.1:5000/v2.0/ec2tokens',
   $default_transport_url              = $::os_service_default,
-  $rpc_backend                        = $::os_service_default,
   $rpc_response_timeout               = $::os_service_default,
   $control_exchange                   = $::os_service_default,
   $rabbit_ha_queues                   = $::os_service_default,
@@ -389,6 +388,7 @@ class heat(
   $rabbit_userid                      = $::os_service_default,
   $rabbit_password                    = $::os_service_default,
   $rabbit_virtual_host                = $::os_service_default,
+  $rpc_backend                        = $::os_service_default,
 ) {
 
   include ::heat::logging
@@ -405,10 +405,12 @@ class heat(
     !is_service_default($rabbit_password) or
     !is_service_default($rabbit_port) or
     !is_service_default($rabbit_userid) or
-    !is_service_default($rabbit_virtual_host) {
+    !is_service_default($rabbit_virtual_host) or
+    !is_service_default($rpc_backend) {
     warning("heat::rabbit_host, heat::rabbit_hosts, heat::rabbit_password, \
-heat::rabbit_port, heat::rabbit_userid and heat::rabbit_virtual_host are \
+heat::rabbit_port, heat::rabbit_userid, heat::rabbit_virtual_host and \
-deprecated. Please use heat::default_transport_url instead.")
+heat::rpc_backend are deprecated. Please use heat::default_transport_url \
+instead.")
   }
 
   package { 'heat-common':
@@ -421,7 +423,6 @@ deprecated. Please use heat::default_transport_url instead.")
     purge => $purge_config,
   }
 
-  if $rpc_backend == 'rabbit' or is_service_default($rpc_backend) {
   if $rabbit_heartbeat_timeout_threshold == 0 {
     warning('Default value for rabbit_heartbeat_timeout_threshold parameter is different from OpenStack project defaults')
   }
@@ -446,8 +447,7 @@ deprecated. Please use heat::default_transport_url instead.")
     rabbit_hosts                => $rabbit_hosts,
     rabbit_ha_queues            => $rabbit_ha_queues,
   }
-  }
+
-  elsif $rpc_backend == 'amqp' {
   oslo::messaging::amqp { 'heat_config':
     server_request_prefix  => $amqp_server_request_prefix,
     broadcast_prefix       => $amqp_broadcast_prefix,
@@ -466,7 +466,6 @@ deprecated. Please use heat::default_transport_url instead.")
     username               => $amqp_username,
     password               => $amqp_password,
   }
-  }
 
   $auth_url = $::heat::keystone::authtoken::auth_url
   $keystone_username = $::heat::keystone::authtoken::username

releasenotes/notes/deprecate_rpc_backend_parameter-46ffa292fb2502eb.yaml

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

spec/classes/heat_init_spec.rb

@@ -68,7 +68,7 @@ describe 'heat' do
     it_configures 'with overriden transport_url parameter'
     it_configures 'with notification_driver set to a string'
 
-    context 'with amqp rpc_backend value' do
+    context 'with amqp messaging' do
       it_configures 'amqp support'
     end
   end
@@ -459,8 +459,6 @@ describe 'heat' do
 
   shared_examples_for 'amqp support' do
     context 'with default parameters' do
-      before { params.merge!( :rpc_backend => 'amqp' ) }
-
       it { is_expected.to contain_heat_config('oslo_messaging_amqp/server_request_prefix').with_value('<SERVICE DEFAULT>') }
       it { is_expected.to contain_heat_config('oslo_messaging_amqp/broadcast_prefix').with_value('<SERVICE DEFAULT>') }
       it { is_expected.to contain_heat_config('oslo_messaging_amqp/group_request_prefix').with_value('<SERVICE DEFAULT>') }
@@ -481,7 +479,6 @@ describe 'heat' 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',