fix(ct): adapt cluster setup helper to replicant nodes

Before this change, trying to start cluster consisting of cores +
replicants resulted in error joining replicant node to the cluster.

apps/emqx/test/emqx_common_test_helpers.erl

@@ -652,10 +652,13 @@ ensure_quic_listener(Name, UdpPort, ExtraSettings) ->
     %% Extras app starting handler. It is the second arg passed to emqx_common_test_helpers:start_apps/2
     env_handler => fun((AppName :: atom()) -> term()),
     %% Application env preset before calling `emqx_common_test_helpers:start_apps/2`
-    env => {AppName :: atom(), Key :: atom(), Val :: term()},
+    env => [{AppName :: atom(), Key :: atom(), Val :: term()}],
     %% Whether to execute `emqx_config:init_load(SchemaMod)`
     %% default: true
     load_schema => boolean(),
+    %% Which node in the cluster to join to.
+    %% default: first core node
+    join_to => node(),
     %% If we want to exercise the scenario where a node joins an
     %% existing cluster where there has already been some
     %% configuration changes (via cluster rpc), then we need to enable
@@ -690,28 +693,38 @@ emqx_cluster(Specs0, CommonOpts) ->
     ]),
     %% Set the default node of the cluster:
     CoreNodes = [node_name(Name) || {{core, Name, _}, _} <- Specs],
-    JoinTo0 =
+    JoinTo =
         case CoreNodes of
             [First | _] -> First;
             _ -> undefined
         end,
-    JoinTo =
+    NodeOpts = fun(Number) ->
-        case maps:find(join_to, CommonOpts) of
+        #{
-            {ok, true} -> JoinTo0;
-            {ok, JT} -> JT;
-            error -> JoinTo0
-        end,
-    [
-        {Name,
-            merge_opts(Opts, #{
             base_port => base_port(Number),
-                join_to => JoinTo,
             env => [
                 {mria, core_nodes, CoreNodes},
-                    {mria, node_role, Role},
                 {gen_rpc, client_config_per_node, {internal, GenRpcPorts}}
             ]
-            })}
+        }
+    end,
+    RoleOpts = fun
+        (core) ->
+            #{
+                join_to => JoinTo,
+                env => [
+                    {mria, node_role, core}
+                ]
+            };
+        (replicant) ->
+            #{
+                env => [
+                    {mria, node_role, replicant},
+                    {ekka, cluster_discovery, {static, [{seeds, CoreNodes}]}}
+                ]
+            }
+    end,
+    [
+        {Name, merge_opts(merge_opts(NodeOpts(Number), RoleOpts(Role)), Opts)}
      || {{Role, Name, Opts}, Number} <- Specs
     ].
 

apps/emqx_bridge/test/emqx_bridge_api_SUITE.erl

@@ -140,7 +140,7 @@ mk_cluster_specs(Config, Opts) ->
         {core, emqx_bridge_api_SUITE1, #{}},
         {core, emqx_bridge_api_SUITE2, #{}}
     ],
-    CommonOpts = #{
+    CommonOpts = Opts#{
         env => [{emqx, boot_modules, [broker]}],
         apps => [],
         % NOTE
@@ -157,7 +157,6 @@ mk_cluster_specs(Config, Opts) ->
         load_apps => ?SUITE_APPS ++ [emqx_dashboard],
         env_handler => fun load_suite_config/1,
         load_schema => false,
-        join_to => maps:get(join_to, Opts, true),
         priv_data_dir => ?config(priv_dir, Config)
     },
     emqx_common_test_helpers:emqx_cluster(Specs, CommonOpts).

apps/emqx_conf/test/emqx_conf_app_SUITE.erl

@@ -247,7 +247,6 @@ cluster(Specs, Config) ->
         {env, Env},
         {apps, [emqx_conf]},
         {load_schema, false},
-        {join_to, true},
         {priv_data_dir, PrivDataDir},
         {env_handler, fun
             (emqx) ->

apps/emqx_management/test/emqx_mgmt_api_listeners_SUITE.erl

@@ -284,7 +284,6 @@ cluster(Specs) ->
         {env, Env},
         {apps, [emqx_conf]},
         {load_schema, false},
-        {join_to, true},
         {env_handler, fun
             (emqx) ->
                 application:set_env(emqx, boot_modules, []),

apps/emqx_management/test/emqx_mgmt_api_nodes_SUITE.erl

@@ -159,7 +159,6 @@ cluster(Specs) ->
         {env, Env},
         {apps, [emqx_conf, emqx_management]},
         {load_schema, false},
-        {join_to, true},
         {env_handler, fun
             (emqx) ->
                 application:set_env(emqx, boot_modules, []),

apps/emqx_management/test/emqx_mgmt_data_backup_SUITE.erl

@@ -444,7 +444,6 @@ cluster(Config) ->
                 env => [{mria, db_backend, rlog}],
                 load_schema => true,
                 start_autocluster => true,
-                join_to => true,
                 listener_ports => [],
                 conf => [{[dashboard, listeners, http, bind], 0}],
                 env_handler =>