rabbit.autocluster => rabbit.cluster_formation

This name is both more descriptive and helps us avoid any possible
conflicts with rabbitmq-autocluster, in particular in the new config
format (Cuttlefish) that we will introduce for both soon.

Per discussion with @dcorbacho.

Author: michaelklishin

src/rabbit_peer_discovery.erl

@@ -41,7 +41,7 @@
 -spec backend() -> atom().
 
 backend() ->
-  case application:get_env(rabbit, autocluster) of
+  case application:get_env(rabbit, cluster_formation) of
     {ok, Proplist} ->
       proplists:get_value(peer_discovery_backend, Proplist, ?DEFAULT_BACKEND);
     undefined      ->
@@ -53,7 +53,7 @@ backend() ->
 -spec node_type() -> rabbit_types:node_type().
 
 node_type() ->
-  case application:get_env(rabbit, autocluster) of
+  case application:get_env(rabbit, cluster_formation) of
     {ok, Proplist} ->
       proplists:get_value(node_type, Proplist, ?DEFAULT_NODE_TYPE);
     undefined      ->
@@ -147,7 +147,7 @@ inject_randomized_delay() ->
 -spec randomized_delay_range_in_ms() -> {integer(), integer()}.
 
 randomized_delay_range_in_ms() ->
-  {Min, Max} = case application:get_env(rabbit, autocluster) of
+  {Min, Max} = case application:get_env(rabbit, cluster_formation) of
                    {ok, Proplist} ->
                        proplists:get_value(randomized_startup_delay_range, Proplist, ?DEFAULT_STARTUP_RANDOMIZED_DELAY);
                    undefined      ->

src/rabbit_peer_discovery_dns.erl

@@ -31,14 +31,14 @@
 -spec list_nodes() -> {ok, Nodes :: list()} | {error, Reason :: string()}.
 
 list_nodes() ->
-    case application:get_env(rabbit, autocluster) of
+    case application:get_env(rabbit, cluster_formation) of
       undefined         ->
         {[], disc};
-      {ok, Autocluster} ->
-        case proplists:get_value(peer_discovery_dns, Autocluster) of
+      {ok, ClusterFormation} ->
+        case proplists:get_value(peer_discovery_dns, ClusterFormation) of
             undefined ->
               rabbit_log:warning("Peer discovery backend is set to ~s "
-                                 "but final config does not contain rabbit.autocluster.peer_discovery_dns. "
+                                 "but final config does not contain rabbit.cluster_formation.peer_discovery_dns. "
                                  "Cannot discover any nodes because seed hostname is not configured!",
                                  [?MODULE]),
               {[], disc};