add option to disable registration of node during cluster formation

Author: frederikbosch

deps/rabbit/priv/schema/rabbit.schema

@@ -1353,6 +1353,13 @@ end}.
     {datatype, {enum, [disc, disk, ram]}}
 ]}.
 
+%% Register node during cluster formation.
+%%
+
+{mapping, "cluster_formation.registration", "rabbit.cluster_formation.register", [
+    {datatype, {enum, [true, false]}}
+]}.
+
 {translation, "rabbit.cluster_formation.node_type",
 fun(Conf) ->
     %% if peer discovery backend isn't configured, don't generate

deps/rabbit/src/rabbit_peer_discovery.erl

@@ -46,6 +46,9 @@
 %% a new cluster as a virgin node
 -define(DEFAULT_NODE_TYPE, disc).
 
+%% register node by default
+-define(DEFAULT_REGISTRATION, true).
+
 %% default node prefix to attach to discovered hostnames
 -define(DEFAULT_PREFIX, "rabbit").
 
@@ -82,6 +85,16 @@ node_type() ->
             ?DEFAULT_NODE_TYPE
     end.
 
+-spec registration() -> true | false.
+
+registration() ->
+    case application:get_env(rabbit, cluster_formation) of
+        {ok, Proplist} ->
+            proplists:get_value(registration, Proplist, ?DEFAULT_REGISTRATION);
+        undefined ->
+            ?DEFAULT_REGISTRATION
+    end.
+
 -spec lock_acquisition_failure_mode() -> ignore | fail.
 
 lock_acquisition_failure_mode() ->
@@ -968,35 +981,51 @@ error_description({invalid_cluster_node_type, BadType}) ->
 -spec maybe_register() -> ok.
 
 maybe_register() ->
-    Backend = persistent_term:get(?PT_PEER_DISC_BACKEND, backend()),
-    case Backend:supports_registration() of
+    case registration() of
         true ->
-            ?LOG_DEBUG(
-               "Peer discovery: registering this node",
-               #{domain => ?RMQLOG_DOMAIN_PEER_DISC}),
-            register(Backend),
-            _ = Backend:post_registration(),
-            ok;
+            Backend = persistent_term:get(?PT_PEER_DISC_BACKEND, backend()),
+            case Backend:supports_registration() of
+                true ->
+                    ?LOG_DEBUG(
+                       "Peer discovery: registering this node",
+                       #{domain => ?RMQLOG_DOMAIN_PEER_DISC}),
+                    register(Backend),
+                    _ = Backend:post_registration(),
+                    ok;
+                false ->
+                    ?LOG_DEBUG(
+                       "Peer discovery: registration unsupported, skipping register",
+                       #{domain => ?RMQLOG_DOMAIN_PEER_DISC}),
+                    ok
+            end.
         false ->
             ?LOG_DEBUG(
-               "Peer discovery: registration unsupported, skipping register",
+               "Peer discovery: registration disabled, skipping register",
                #{domain => ?RMQLOG_DOMAIN_PEER_DISC}),
             ok
     end.
 
 -spec maybe_unregister() -> ok.
 
 maybe_unregister() ->
-    Backend = persistent_term:get(?PT_PEER_DISC_BACKEND),
-    case Backend:supports_registration() of
+    case registration() of
         true ->
-            ?LOG_DEBUG(
-               "Peer discovery: unregistering this node",
-               #{domain => ?RMQLOG_DOMAIN_PEER_DISC}),
-            unregister(Backend);
+            Backend = persistent_term:get(?PT_PEER_DISC_BACKEND),
+            case Backend:supports_registration() of
+                true ->
+                    ?LOG_DEBUG(
+                       "Peer discovery: unregistering this node",
+                       #{domain => ?RMQLOG_DOMAIN_PEER_DISC}),
+                    unregister(Backend);
+                false ->
+                    ?LOG_DEBUG(
+                       "Peer discovery: registration unsupported, skipping unregister",
+                       #{domain => ?RMQLOG_DOMAIN_PEER_DISC}),
+                    ok
+            end.
         false ->
             ?LOG_DEBUG(
-               "Peer discovery: registration unsupported, skipping unregister",
+               "Peer discovery: registration disabled, skipping unregister",
                #{domain => ?RMQLOG_DOMAIN_PEER_DISC}),
             ok
     end.