Merge pull request #14363 from rabbitmq/mergify/bp/v4.1.x/pr-14348

Add config option for enabling local_random_exchange (backport #14348)

Author: michaelklishin

deps/rabbit/priv/schema/rabbit.schema

@@ -2606,7 +2606,10 @@ fun(Conf) ->
     end
 end}.
 
-
+%% Enable or disable local random exchange
+{mapping, "exchange_types.local_random.enabled", "rabbit.local_random_exchange_enabled", [
+    {datatype, {enum, [true, false]}}
+]}.
 
 %%
 %% Backing queue version

deps/rabbit/src/rabbit_exchange_type_local_random.erl

@@ -60,11 +60,19 @@ serialise_events() -> false.
 validate(_X) ->
     case rabbit_feature_flags:is_enabled(?MODULE) of
         true ->
-            ok;
+            case application:get_env(rabbit, local_random_exchange_enabled, true) of
+                true ->
+                    ok;
+                false ->
+                    rabbit_misc:protocol_error(
+                      precondition_failed,
+                      "x-local-random exchange is disabled by configuration", [],
+                      'exchange.declare')
+            end;
         false ->
-            rabbit_misc:amqp_error(
+            rabbit_misc:protocol_error(
               precondition_failed,
-              "x-local-random exchange feature not available", [],
+              "x-local-random exchange feature flag is disabled", [],
               'exchange.declare')
     end.
 

deps/rabbit/test/rabbit_local_random_exchange_SUITE.erl

@@ -21,7 +21,8 @@ groups() ->
     [
      {non_parallel_tests, [], [
                                routed_to_one_local_queue_test,
-                               no_route
+                               no_route,
+                               disable_local_random_exchange_config_test
                               ]}
     ].
 
@@ -196,6 +197,30 @@ make_queue_name(Config, Node) ->
     B = rabbit_ct_helpers:get_config(Config, test_resource_name),
     erlang:list_to_binary("q-" ++ B ++ "-" ++ integer_to_list(Node)).
 
+disable_local_random_exchange_config_test(Config) ->
+    E = make_exchange_name(Config, "config-test"),
+    
+    %% Disable the config flag
+    rabbit_ct_broker_helpers:rpc(Config, 0, application, set_env,
+                                 [rabbit, local_random_exchange_enabled, false]),
+    
+    %% Try to create exchange - should fail
+    ?assertExit({{shutdown, {server_initiated_close, 406, _}}, _},
+                declare_exchange(Config, E)),
+    
+    %% Re-enable the config flag
+    rabbit_ct_broker_helpers:rpc(Config, 0, application, set_env,
+                                 [rabbit, local_random_exchange_enabled, true]),
+    
+    %% Now exchange creation should succeed
+    declare_exchange(Config, E),
+    
+    %% Clean up
+    run_on_node(Config, 0,
+                fun(Chan) ->
+                        amqp_channel:call(Chan, #'exchange.delete'{exchange = E})
+                end).
+
 flush(T) ->
     receive X ->
                 ct:pal("flushed ~p", [X]),