RabbitMQ should use net_ticktime

We no longer need to force low-level TCP timeouts for dead client
detection, but should continue tuning the timeout for dead peer
detection between cluster nodes.  Using the erlang net_ticktime option
is preferrable here.

Closes-Bug: 1717006
Change-Id: Ibd29c03bd69818d79396c379a2d638c018a04b82

puppet/services/rabbitmq.yaml

@@ -57,6 +57,12 @@ parameters:
       overridden to CEIL(N/2) where N is the number of nodes running rabbitmq.
     default: -1
     type: number
+  RabbitNetTickTime:
+    description:
+      The number of seconds to configure the value of the erlang
+      net_ticktime kernel variable.
+    default: 15
+    type: number
   MonitoringSubscriptionRabbitmq:
     default: 'overcloud-rabbitmq'
     type: string
@@ -97,11 +103,12 @@ outputs:
               NODE_PORT: ''
               NODE_IP_ADDRESS: ''
               RABBITMQ_NODENAME: "rabbit@%{::hostname}"
-              RABBITMQ_SERVER_ERL_ARGS: '"+K true +P 1048576 -kernel inet_default_connect_options [{nodelay,true},{raw,6,18,<<15000:64/native>>}] -kernel inet_default_listen_options [{raw,6,18,<<15000:64/native>>}]"'
+              RABBITMQ_SERVER_ERL_ARGS: '"+K true +P 1048576 -kernel inet_default_connect_options [{nodelay,true}]"'
               'export ERL_EPMD_ADDRESS': "%{hiera('rabbitmq::interface')}"
             rabbitmq_kernel_variables:
               inet_dist_listen_min: '25672'
               inet_dist_listen_max: '25672'
+              net_ticktime: {get_param: RabbitNetTickTime}
             rabbitmq_config_variables:
               cluster_partition_handling: 'pause_minority'
               queue_master_locator: '<<"min-masters">>'

releasenotes/notes/rabbit-net_ticktime-519f904e52218c2d.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    A new parameter, RabbitNetTickTime, allows tuning the Erlang
+    net_ticktime parameter for rabbitmq-server.  The default value is
+    15 seconds.  This replaces previous tunings in the RabbitMQ
+    environment file which set socket options forcing
+    TCP_USER_TIMEOUT to 15 seconds.