Introduce the new rabbit_heartbeat_in_pthread option

oslo.messaging RabbitMQ driver have now a new option that allow user to
run the RabbitMQ heartbeat over a native python thread.

These change allow user to use this new option.

Change-Id: Ica6cdc200d3f736573a0b78c8163e1c17567b3ef
Closes-Bug: #1840868

manifests/init.pp

@@ -92,6 +92,16 @@
 #   the heartbeat will be checked every 30 seconds. (integer value)
 #   Defaults to $::os_service_default
 #
+# [*rabbit_heartbeat_in_pthread*]
+#   (Optional) EXPERIMENTAL: Run the health check heartbeat thread
+#   through a native python thread. By default if this
+#   option isn't provided the  health check heartbeat will
+#   inherit the execution model from the parent process. By
+#   example if the parent process have monkey patched the
+#   stdlib by using eventlet/greenlet then the heartbeat
+#   will be run through a green thread.
+#   Defaults to $::os_service_default
+#
 # [*kombu_ssl_ca_certs*]
 #   (optional) SSL certification authority file (valid only if SSL enabled).
 #   (string value)
@@ -436,6 +446,7 @@ class nova(
   $rabbit_use_ssl                         = $::os_service_default,
   $rabbit_heartbeat_timeout_threshold     = $::os_service_default,
   $rabbit_heartbeat_rate                  = $::os_service_default,
+  $rabbit_heartbeat_in_pthread            = $::os_service_default,
   $rabbit_ha_queues                       = $::os_service_default,
   $kombu_ssl_ca_certs                     = $::os_service_default,
   $kombu_ssl_certfile                     = $::os_service_default,
@@ -639,6 +650,7 @@ but should be one of: ssh-rsa, ssh-dsa, ssh-ecdsa.")
     rabbit_use_ssl              => $rabbit_use_ssl,
     heartbeat_timeout_threshold => $rabbit_heartbeat_timeout_threshold,
     heartbeat_rate              => $rabbit_heartbeat_rate,
+    heartbeat_in_pthread        => $rabbit_heartbeat_in_pthread,
     kombu_reconnect_delay       => $kombu_reconnect_delay,
     kombu_failover_strategy     => $kombu_failover_strategy,
     amqp_durable_queues         => $amqp_durable_queues,

releasenotes/notes/rabbitmq-heartbeat-over-pthread-9b65893bf0406753.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Allow users to run the RabbitMQ heartbeat over a native python thread in the
+    oslo.messaging RabbitMQ driver, by using the `rabbit_heartbeat_in_pthread`
+    option in configuration.

spec/classes/nova_init_spec.rb

@@ -40,6 +40,7 @@ describe 'nova' do
         is_expected.to contain_nova_config('DEFAULT/transport_url').with_value('<SERVICE DEFAULT>')
         is_expected.to contain_nova_config('oslo_messaging_rabbit/heartbeat_timeout_threshold').with_value('<SERVICE DEFAULT>')
         is_expected.to contain_nova_config('oslo_messaging_rabbit/heartbeat_rate').with_value('<SERVICE DEFAULT>')
+        is_expected.to contain_nova_config('oslo_messaging_rabbit/heartbeat_in_pthread').with_value('<SERVICE DEFAULT>')
       end
 
       it 'configures various things' do
@@ -79,6 +80,7 @@ describe 'nova' do
           :control_exchange                        => 'nova',
           :rabbit_heartbeat_timeout_threshold      => '60',
           :rabbit_heartbeat_rate                   => '10',
+          :rabbit_heartbeat_in_pthread             => true,
           :lock_path                               => '/var/locky/path',
           :state_path                              => '/var/lib/nova2',
           :service_down_time                       => '120',
@@ -137,6 +139,7 @@ describe 'nova' do
         is_expected.to contain_nova_config('DEFAULT/control_exchange').with_value('nova')
         is_expected.to contain_nova_config('oslo_messaging_rabbit/heartbeat_timeout_threshold').with_value('60')
         is_expected.to contain_nova_config('oslo_messaging_rabbit/heartbeat_rate').with_value('10')
+        is_expected.to contain_nova_config('oslo_messaging_rabbit/heartbeat_in_pthread').with_value(true)
       end
 
       it 'configures host' do