fix(mqtt-bridge): allow to configure `clean_start` for ingresses

apps/emqx_bridge/test/emqx_bridge_mqtt_SUITE.erl

@@ -242,26 +242,26 @@ t_mqtt_conn_bridge_ingress(_) ->
 
     ok.
 
-t_mqtt_conn_bridge_ignores_clean_start(_) ->
+t_mqtt_egress_bridge_ignores_clean_start(_) ->
     BridgeName = atom_to_binary(?FUNCTION_NAME),
     BridgeID = create_bridge(
         ?SERVER_CONF(<<"user1">>)#{
             <<"type">> => ?TYPE_MQTT,
             <<"name">> => BridgeName,
-            <<"ingress">> => ?INGRESS_CONF,
+            <<"egress">> => ?EGRESS_CONF,
             <<"clean_start">> => false
         }
     ),
 
-    {ok, 200, BridgeJSON} = request(get, uri(["bridges", BridgeID]), []),
-    Bridge = jsx:decode(BridgeJSON),
-
-    %% verify that there's no `clean_start` in response
-    ?assertEqual(#{}, maps:with([<<"clean_start">>], Bridge)),
+    {ok, _, #{state := #{name := WorkerName}}} =
+        emqx_resource:get_instance(emqx_bridge_resource:resource_id(BridgeID)),
+    ?assertMatch(
+        #{clean_start := true},
+        maps:from_list(emqx_connector_mqtt_worker:info(WorkerName))
+    ),
 
     %% delete the bridge
     {ok, 204, <<>>} = request(delete, uri(["bridges", BridgeID]), []),
-    {ok, 200, <<"[]">>} = request(get, uri(["bridges"]), []),
 
     ok.
 

apps/emqx_connector/i18n/emqx_connector_mqtt_schema.conf

@@ -159,8 +159,8 @@ broker MUST support this feature."""
 
     clean_start {
         desc {
-          en: "The clean-start or the clean-session of the MQTT protocol"
-          zh: "MQTT 清除会话"
+          en: "Whether or not to start a clean session when reconnecting a remote broker for ingress bridge"
+          zh: "与 ingress MQTT 桥的远程服务器重连时是否清除老的 MQTT 会话。"
         }
         label: {
               en: "Clean Session"

apps/emqx_connector/src/emqx_connector_mqtt.erl

@@ -251,6 +251,7 @@ basic_config(
         server := Server,
         proto_ver := ProtoVer,
         bridge_mode := BridgeMode,
+        clean_start := CleanStart,
         keepalive := KeepAlive,
         retry_interval := RetryIntv,
         max_inflight := MaxInflight,
@@ -270,11 +271,8 @@ basic_config(
         %% non-standard mqtt connection packets will be filtered out by LB.
         %% So let's disable bridge_mode.
         bridge_mode => BridgeMode,
-        %% NOTE
-        %% We are ignoring the user configuration here because there's currently no reliable way
-        %% to ensure proper session recovery according to the MQTT spec.
-        clean_start => true,
         keepalive => ms_to_s(KeepAlive),
+        clean_start => CleanStart,
         retry_interval => RetryIntv,
         max_inflight => MaxInflight,
         ssl => EnableSsl,

apps/emqx_connector/src/mqtt/emqx_connector_mqtt_schema.erl

@@ -112,9 +112,7 @@ fields("server_configs") ->
                 boolean(),
                 #{
                     default => true,
-                    desc => ?DESC("clean_start"),
-                    hidden => true,
-                    deprecated => {since, "v5.0.16"}
+                    desc => ?DESC("clean_start")
                 }
             )},
         {keepalive, mk_duration("MQTT Keepalive.", #{default => "300s"})},

apps/emqx_connector/src/mqtt/emqx_connector_mqtt_worker.erl

@@ -75,6 +75,7 @@
     connect/1,
     status/1,
     ping/1,
+    info/1,
     send_to_remote/2,
     send_to_remote_async/3
 ]).
@@ -145,6 +146,16 @@ mk_client_options(Conf, BridgeOpts) ->
     Mountpoint = maps:get(receive_mountpoint, BridgeOpts, undefined),
     Subscriptions = maps:get(subscriptions, Conf),
     Vars = emqx_connector_mqtt_msg:make_pub_vars(Mountpoint, Subscriptions),
+    CleanStart =
+        case Subscriptions of
+            #{remote := _} ->
+                maps:get(clean_start, BridgeOpts);
+            undefined ->
+                %% NOTE
+                %% We are ignoring the user configuration here because there's currently no reliable way
+                %% to ensure proper session recovery according to the MQTT spec.
+                true
+        end,
     Opts = maps:without(
         [
             address,
@@ -160,6 +171,7 @@ mk_client_options(Conf, BridgeOpts) ->
     Opts#{
         msg_handler => mk_client_event_handler(Vars, #{server => Server}),
         hosts => [HostPort],
+        clean_start => CleanStart,
         force_ping => true,
         proto_ver => maps:get(proto_ver, BridgeOpts, v4)
     }.
@@ -205,10 +217,12 @@ subscribe_remote_topics(_Ref, undefined) ->
 stop(Ref) ->
     emqtt:stop(ref(Ref)).
 
+info(Ref) ->
+    emqtt:info(ref(Ref)).
+
 status(Ref) ->
     try
-        Info = emqtt:info(ref(Ref)),
-        case proplists:get_value(socket, Info) of
+        case proplists:get_value(socket, info(Ref)) of
             Socket when Socket /= undefined ->
                 connected;
             undefined ->