refactor(connector): add connector configs

apps/emqx/test/emqx_common_test_helpers.erl

@@ -132,7 +132,7 @@ start_apps(Apps) ->
 start_apps(Apps, Handler) when is_function(Handler) ->
     %% Load all application code to beam vm first
     %% Because, minirest, ekka etc.. application will scan these modules
-    lists:foreach(fun load/1, [emqx_machine, emqx_conf, emqx | Apps]),
+    lists:foreach(fun load/1, [emqx_conf, emqx | Apps]),
     ekka:start(),
     lists:foreach(fun(App) -> start_app(App, Handler) end, [emqx | Apps]).
 

apps/emqx_bridge/etc/emqx_bridge.conf

@@ -3,73 +3,54 @@
 ##--------------------------------------------------------------------
 
 ## MQTT bridges to/from another MQTT broker
-bridges.mqtt.my_mqtt_bridge_to_aws {
-    server = "127.0.0.1:1883"
-    proto_ver = "v4"
-    username = "username1"
-    password = ""
-    clean_start = true
-    keepalive = 300
-    retry_interval = "30s"
-    max_inflight = 32
-    reconnect_interval = "30s"
-    bridge_mode = true
-    replayq {
-        dir = "{{ platform_data_dir }}/replayq/bridge_mqtt/"
-        seg_bytes = "100MB"
-        offload = false
-    }
-    ssl {
-        enable = false
-        keyfile = "{{ platform_etc_dir }}/certs/client-key.pem"
-        certfile = "{{ platform_etc_dir }}/certs/client-cert.pem"
-        cacertfile = "{{ platform_etc_dir }}/certs/cacert.pem"
-    }
-
-    ## topic mappings for this bridge
-    ingress {
-        from_remote_topic = "aws/#"
-        subscribe_qos = 1
-        to_local_topic = "from_aws/${topic}"
-        payload = "${payload}"
-        qos = "${qos}"
-        retain = "${retain}"
-    }
-
-    egress {
-        from_local_topic = "emqx/#"
-        to_remote_topic = "from_emqx/${topic}"
-        payload = "${payload}"
-        qos = 1
-        retain = false
-    }
-
-}
+#bridges.mqtt.my_ingress_mqtt_bridge {
+#    connector = my_mqtt_connector
+#    direction = ingress
+#    ## topic mappings for this bridge
+#    from_remote_topic = "aws/#"
+#    subscribe_qos = 1
+#    to_local_topic = "from_aws/${topic}"
+#    payload = "${payload}"
+#    qos = "${qos}"
+#    retain = "${retain}"
+#
+#}
+#
+#bridges.mqtt.my_egress_mqtt_bridge {
+#    connector = my_mqtt_connector
+#    direction = egress
+#    ## topic mappings for this bridge
+#    from_local_topic = "emqx/#"
+#    to_remote_topic = "from_emqx/${topic}"
+#    payload = "${payload}"
+#    qos = 1
+#    retain = false
+#}
 
 ## HTTP bridges to an HTTP server
-bridges.http.my_http_bridge {
-    ## NOTE: we cannot use placehodler variables in the `scheme://host:port` part of the url string
-    url = "http://localhost:9901/messages/${topic}"
-    request_timeout = "30s"
-    connect_timeout = "30s"
-    max_retries = 3
-    retry_interval = "10s"
-    pool_type = "random"
-    pool_size = 4
-    enable_pipelining = true
-    ssl {
-        enable = false
-        keyfile = "{{ platform_etc_dir }}/certs/client-key.pem"
-        certfile = "{{ platform_etc_dir }}/certs/client-cert.pem"
-        cacertfile = "{{ platform_etc_dir }}/certs/cacert.pem"
-    }
-
-    from_local_topic = "emqx_http/#"
-    ## the following config entries can use placehodler variables:
-    ##   url, method, body, headers
-    method = post
-    body = "${payload}"
-    headers {
-        "content-type": "application/json"
-    }
-}
+#bridges.http.my_http_bridge {
+#    ## NOTE: we cannot use placehodler variables in the `scheme://host:port` part of the url string
+#    url = "http://localhost:9901/messages/${topic}"
+#    request_timeout = "30s"
+#    connect_timeout = "30s"
+#    max_retries = 3
+#    retry_interval = "10s"
+#    pool_type = "random"
+#    pool_size = 4
+#    enable_pipelining = true
+#    ssl {
+#        enable = false
+#        keyfile = "{{ platform_etc_dir }}/certs/client-key.pem"
+#        certfile = "{{ platform_etc_dir }}/certs/client-cert.pem"
+#        cacertfile = "{{ platform_etc_dir }}/certs/cacert.pem"
+#    }
+#
+#    from_local_topic = "emqx_http/#"
+#    ## the following config entries can use placehodler variables:
+#    ##   url, method, body, headers
+#    method = post
+#    body = "${payload}"
+#    headers {
+#        "content-type": "application/json"
+#    }
+#}

apps/emqx_bridge/src/emqx_bridge.erl

@@ -84,7 +84,7 @@ on_message_publish(Message = #message{topic = Topic, flags = Flags}) ->
 send_message(BridgeId, Message) ->
     {BridgeType, BridgeName} = parse_bridge_id(BridgeId),
     ResId = emqx_bridge:resource_id(BridgeType, BridgeName),
-    emqx_resource:query(ResId, {send_message, BridgeId, Message}).
+    emqx_resource:query(ResId, {send_message, Message}).
 
 config_key_path() ->
     [bridges].
@@ -178,7 +178,7 @@ create(Type, Name, Conf) ->
         config => Conf}),
     ResId = resource_id(Type, Name),
     case emqx_resource:create(ResId,
-            emqx_bridge:resource_type(Type), parse_confs(Type, Conf)) of
+            emqx_bridge:resource_type(Type), parse_confs(Type, Name, Conf)) of
         {ok, already_created} ->
             emqx_resource:get_instance(ResId);
         {ok, Data} ->
@@ -199,7 +199,7 @@ update(Type, Name, {_OldConf, Conf}) ->
     ?SLOG(info, #{msg => "update bridge", type => Type, name => Name,
         config => Conf}),
     emqx_resource:recreate(resource_id(Type, Name),
-        emqx_bridge:resource_type(Type), parse_confs(Type, Conf), []).
+        emqx_bridge:resource_type(Type), parse_confs(Type, Name, Conf), []).
 
 remove(Type, Name, _Conf) ->
     ?SLOG(info, #{msg => "remove bridge", type => Type, name => Name}),
@@ -227,8 +227,12 @@ get_matched_bridges(Topic) ->
     Bridges = emqx:get_config([bridges], #{}),
     maps:fold(fun (BType, Conf, Acc0) ->
         maps:fold(fun
-            (BName, #{egress := Egress}, Acc1) ->
+            %% Confs for MQTT, Kafka bridges have the `direction` flag
+            (_BName, #{direction := ingress}, Acc1) ->
+                Acc1;
+            (BName, #{direction := egress} = Egress, Acc1) ->
                 get_matched_bridge_id(Egress, Topic, BType, BName, Acc1);
+            %% HTTP, MySQL bridges only have egress direction
             (BName, BridgeConf, Acc1) ->
                 get_matched_bridge_id(BridgeConf, Topic, BType, BName, Acc1)
         end, Acc0, Conf)
@@ -240,12 +244,13 @@ get_matched_bridge_id(#{from_local_topic := Filter}, Topic, BType, BName, Acc) -
         false -> Acc
     end.
 
-parse_confs(http, #{ url := Url
-                   , method := Method
-                   , body := Body
-                   , headers := Headers
-                   , request_timeout := ReqTimeout
-                   } = Conf) ->
+parse_confs(http, _Name,
+        #{ url := Url
+         , method := Method
+         , body := Body
+         , headers := Headers
+         , request_timeout := ReqTimeout
+         } = Conf) ->
     {BaseUrl, Path} = parse_url(Url),
     {ok, BaseUrl2} = emqx_http_lib:uri_parse(BaseUrl),
     Conf#{ base_url => BaseUrl2
@@ -257,8 +262,20 @@ parse_confs(http, #{ url := Url
              , request_timeout => ReqTimeout
              }
          };
-parse_confs(_Type, Conf) ->
-    Conf.
+parse_confs(Type, Name, #{connector := ConnName, direction := Direction} = Conf) ->
+    ConnectorConfs = emqx:get_config([connectors, Type, ConnName]),
+    make_resource_confs(Direction, ConnectorConfs,
+        maps:without([connector, direction], Conf), Name).
+
+make_resource_confs(ingress, ConnectorConfs, BridgeConf, Name) ->
+    BName = bin(Name),
+    ConnectorConfs#{
+        ingress => BridgeConf#{hookpoint => <<"$bridges/", BName/binary>>}
+    };
+make_resource_confs(egress, ConnectorConfs, BridgeConf, _Name) ->
+    ConnectorConfs#{
+        egress => BridgeConf
+    }.
 
 parse_url(Url) ->
     case string:split(Url, "//", leading) of

apps/emqx_bridge/src/emqx_bridge_schema.erl

@@ -11,17 +11,26 @@ roots() -> [bridges].
 
 fields(bridges) ->
     [ {mqtt,
-       sc(hoconsc:map(name, ref("mqtt_bridge")),
+       sc(hoconsc:map(name, hoconsc:union([ ref("ingress_mqtt_bridge")
+                                          , ref("egress_mqtt_bridge")
+                                          ])),
           #{ desc => "MQTT bridges"
-           })}
+          })}
     , {http,
        sc(hoconsc:map(name, ref("http_bridge")),
           #{ desc => "HTTP bridges"
-           })}
+          })}
     ];
 
-fields("mqtt_bridge") ->
-    emqx_connector_mqtt:fields("config");
+fields("ingress_mqtt_bridge") ->
+    [ direction(ingress, emqx_connector_mqtt_schema:ingress_desc())
+    , connector_name()
+    ] ++ proplists:delete(hookpoint, emqx_connector_mqtt_schema:fields("ingress"));
+
+fields("egress_mqtt_bridge") ->
+    [ direction(egress, emqx_connector_mqtt_schema:egress_desc())
+    , connector_name()
+    ] ++ emqx_connector_mqtt_schema:fields("egress");
 
 fields("http_bridge") ->
     basic_config_http() ++
@@ -85,6 +94,24 @@ How long will the HTTP request timeout.
            })}
     ].
 
+direction(Dir, Desc) ->
+    {direction,
+        sc(Dir,
+           #{ nullable => false
+            , desc => "The direction of the bridge. Can be one of 'ingress' or 'egress'.<br>" ++
+                      Desc
+            })}.
+
+connector_name() ->
+    {connector,
+        sc(binary(),
+           #{ nullable => false
+            , desc =>"""
+The connector name to be used for this bridge.
+Connectors are configured by 'connectors.<type>.<name>
+"""
+            })}.
+
 basic_config_http() ->
     proplists:delete(base_url, emqx_connector_http:fields(config)).
 

apps/emqx_bridge/test/emqx_bridge_api_SUITE.erl

@@ -112,6 +112,7 @@ t_crud_apis(_) ->
     {ok, 200, <<"[]">>} = request(get, uri(["bridges"]), []),
 
     %% then we add a http bridge now
+    %% PUT /bridges/:id will create or update a bridge
     {ok, 200, Bridge} = request(put, uri(["bridges", "http:test_bridge"]), ?HTTP_BRIDGE(?URL1)),
     %ct:pal("---bridge: ~p", [Bridge]),
     ?assertMatch([ #{ <<"id">> := <<"http:test_bridge">>
@@ -139,11 +140,35 @@ t_crud_apis(_) ->
                     , <<"url">> := ?URL2
                     }], jsx:decode(Bridge2Str)),
 
+    %% get the bridge by id
+    {ok, 200, Bridge3Str} = request(get, uri(["bridges", "http:test_bridge"]), []),
+    ?assertMatch([#{ <<"id">> := <<"http:test_bridge">>
+                    , <<"bridge_type">> := <<"http">>
+                    , <<"is_connected">> := _
+                    , <<"node">> := _
+                    , <<"url">> := ?URL2
+                    }], jsx:decode(Bridge3Str)),
+
     %% delete the bridge
     {ok,200,<<>>} = request(delete, uri(["bridges", "http:test_bridge"]), []),
     {ok, 200, <<"[]">>} = request(get, uri(["bridges"]), []),
     ok.
 
+t_change_is_connnected_to_status() ->
+    error(not_implimented).
+
+t_start_stop_bridges(_) ->
+    start_http_server(9901, fun handle_fun_200_ok/1),
+    {ok, 200, Bridge} = request(put, uri(["bridges", "http:test_bridge"]), ?HTTP_BRIDGE(?URL1)),
+    ?assertMatch(  #{ <<"id">> := <<"http:test_bridge">>
+                    , <<"bridge_type">> := <<"http">>
+                    , <<"is_connected">> := true
+                    , <<"node">> := _
+                    , <<"url">> := ?URL1
+                    }, jsx:decode(Bridge)),
+    {ok, 200, <<>>} = request(put,
+        uri(["nodes", node(), "bridges", "http:test_bridge", "operation", "stop"]),
+        ?HTTP_BRIDGE(?URL1)).
 
 %%--------------------------------------------------------------------
 %% HTTP Request

apps/emqx_conf/src/emqx_conf_schema.erl

@@ -56,6 +56,7 @@
         , emqx_exhook_schema
         , emqx_psk_schema
         , emqx_limiter_schema
+        , emqx_connector_schema
         ]).
 
 namespace() -> undefined.

apps/emqx_connector/etc/emqx_connector.conf

@@ -0,0 +1,23 @@
+#connectors.mqtt.my_mqtt_connector {
+#    server = "127.0.0.1:1883"
+#    proto_ver = "v4"
+#    username = "username1"
+#    password = ""
+#    clean_start = true
+#    keepalive = 300
+#    retry_interval = "30s"
+#    max_inflight = 32
+#    reconnect_interval = "30s"
+#    bridge_mode = true
+#    replayq {
+#        dir = "{{ platform_data_dir }}/replayq/bridge_mqtt/"
+#        seg_bytes = "100MB"
+#        offload = false
+#    }
+#    ssl {
+#        enable = false
+#        keyfile = "{{ platform_etc_dir }}/certs/client-key.pem"
+#        certfile = "{{ platform_etc_dir }}/certs/client-cert.pem"
+#        cacertfile = "{{ platform_etc_dir }}/certs/cacert.pem"
+#    }
+#}

apps/emqx_connector/src/emqx_connector_http.erl

@@ -178,9 +178,9 @@ on_stop(InstId, #{pool_name := PoolName}) ->
                   connector => InstId}),
     ehttpc_sup:stop_pool(PoolName).
 
-on_query(InstId, {send_message, BridgeId, Msg}, AfterQuery, State) ->
+on_query(InstId, {send_message, Msg}, AfterQuery, State) ->
     case maps:get(request, State, undefined) of
-        undefined -> ?SLOG(error, #{msg => "request not found", bridge_id => BridgeId});
+        undefined -> ?SLOG(error, #{msg => "request not found", connector => InstId});
         Request ->
             #{method := Method, path := Path, body := Body, headers := Headers,
               request_timeout := Timeout} = process_request(Request, Msg),

apps/emqx_connector/src/emqx_connector_mqtt.erl

@@ -89,64 +89,70 @@ drop_bridge(Name) ->
 %% ===================================================================
 %% When use this bridge as a data source, ?MODULE:on_message_received/2 will be called
 %% if the bridge received msgs from the remote broker.
-on_message_received(Msg, BridgeId) ->
-    Name = atom_to_binary(BridgeId, utf8),
-    emqx:run_hook(<<"$bridges/", Name/binary>>, [Msg]).
+on_message_received(Msg, HookPoint) ->
+    emqx:run_hook(HookPoint, [Msg]).
 
 %% ===================================================================
 on_start(InstId, Conf) ->
-    "bridge:" ++ NamePrefix = binary_to_list(InstId),
-    BridgeId = list_to_atom(NamePrefix),
+    InstanceId = binary_to_atom(InstId, utf8),
     ?SLOG(info, #{msg => "starting mqtt connector",
-                  connector => BridgeId, config => Conf}),
+                  connector => InstanceId, config => Conf}),
     BasicConf = basic_config(Conf),
-    SubRemoteConf = maps:get(ingress, Conf, #{}),
-    FrowardConf = maps:get(egress, Conf, #{}),
     BridgeConf = BasicConf#{
-        name => BridgeId,
-        clientid => clientid(BridgeId),
-        subscriptions => SubRemoteConf#{
-            to_local_topic => maps:get(to_local_topic, SubRemoteConf, undefined),
-            on_message_received => {fun ?MODULE:on_message_received/2, [BridgeId]}
-        },
-        forwards => FrowardConf#{
-            from_local_topic => maps:get(from_local_topic, FrowardConf, undefined)
-        }
+        name => InstanceId,
+        clientid => clientid(InstanceId),
+        subscriptions => make_sub_confs(maps:get(ingress, Conf, undefined)),
+        forwards => make_forward_confs(maps:get(egress, Conf, undefined))
     },
     case ?MODULE:create_bridge(BridgeConf) of
         {ok, _Pid} ->
-            case emqx_connector_mqtt_worker:ensure_started(BridgeId) of
-                ok -> {ok, #{name => BridgeId}};
+            case emqx_connector_mqtt_worker:ensure_started(InstanceId) of
+                ok -> {ok, #{name => InstanceId}};
                 {error, Reason} -> {error, Reason}
             end;
         {error, {already_started, _Pid}} ->
-            {ok, #{name => BridgeId}};
+            {ok, #{name => InstanceId}};
         {error, Reason} ->
             {error, Reason}
     end.
 
-on_stop(_InstId, #{name := BridgeId}) ->
+on_stop(_InstId, #{name := InstanceId}) ->
     ?SLOG(info, #{msg => "stopping mqtt connector",
-                  connector => BridgeId}),
-    case ?MODULE:drop_bridge(BridgeId) of
+                  connector => InstanceId}),
+    case ?MODULE:drop_bridge(InstanceId) of
         ok -> ok;
         {error, not_found} -> ok;
         {error, Reason} ->
             ?SLOG(error, #{msg => "stop mqtt connector",
-                connector => BridgeId, reason => Reason})
+                connector => InstanceId, reason => Reason})
     end.
 
-on_query(_InstId, {send_message, BridgeId, Msg}, _AfterQuery, _State) ->
+on_query(_InstId, {send_message, Msg}, _AfterQuery, #{name := InstanceId}) ->
     ?SLOG(debug, #{msg => "send msg to remote node", message => Msg,
-        connector => BridgeId}),
-    emqx_connector_mqtt_worker:send_to_remote(BridgeId, Msg).
+        connector => InstanceId}),
+    emqx_connector_mqtt_worker:send_to_remote(InstanceId, Msg).
 
-on_health_check(_InstId, #{name := BridgeId} = State) ->
-    case emqx_connector_mqtt_worker:ping(BridgeId) of
+on_health_check(_InstId, #{name := InstanceId} = State) ->
+    case emqx_connector_mqtt_worker:ping(InstanceId) of
         pong -> {ok, State};
-        _ -> {error, {connector_down, BridgeId}, State}
+        _ -> {error, {connector_down, InstanceId}, State}
     end.
 
+make_sub_confs(undefined) ->
+    undefined;
+make_sub_confs(SubRemoteConf) ->
+    case maps:take(hookpoint, SubRemoteConf) of
+        error -> SubRemoteConf;
+        {HookPoint, SubConf} ->
+            MFA = {?MODULE, on_message_received, [HookPoint]},
+            SubConf#{on_message_received => MFA}
+    end.
+
+make_forward_confs(undefined) ->
+    undefined;
+make_forward_confs(FrowardConf) ->
+    FrowardConf.
+
 basic_config(#{
         server := Server,
         reconnect_interval := ReconnIntv,

apps/emqx_connector/src/emqx_connector_schema.erl

@@ -0,0 +1,28 @@
+-module(emqx_connector_schema).
+
+-behaviour(hocon_schema).
+
+-include_lib("typerefl/include/types.hrl").
+
+-export([roots/0, fields/1]).
+
+%%======================================================================================
+%% Hocon Schema Definitions
+
+roots() -> ["connectors"].
+
+fields("connectors") ->
+    [ {mqtt,
+       sc(hoconsc:map(name,
+            hoconsc:union([ ref("mqtt_connector")
+                          ])),
+          #{ desc => "MQTT bridges"
+          })}
+    ];
+
+fields("mqtt_connector") ->
+    emqx_connector_mqtt_schema:fields("connector").
+
+sc(Type, Meta) -> hoconsc:mk(Type, Meta).
+
+ref(Field) -> hoconsc:ref(?MODULE, Field).

apps/emqx_connector/src/mqtt/emqx_connector_mqtt_mod.erl

@@ -160,13 +160,17 @@ handle_puback(#{packet_id := PktId, reason_code := RC}, _Parent) ->
 
 handle_publish(Msg, undefined) ->
     ?SLOG(error, #{msg => "cannot publish to local broker as"
-                          " ingress_channles' is not configured",
+                          " 'ingress' is not configured",
                    message => Msg});
-handle_publish(Msg, #{on_message_received := {OnMsgRcvdFunc, Args}} = Vars) ->
+handle_publish(Msg, Vars) ->
     ?SLOG(debug, #{msg => "publish to local broker",
                    message => Msg, vars => Vars}),
     emqx_metrics:inc('bridge.mqtt.message_received_from_remote', 1),
-    _ = erlang:apply(OnMsgRcvdFunc, [Msg | Args]),
+    case Vars of
+        #{on_message_received := {Mod, Func, Args}} ->
+            _ = erlang:apply(Mod, Func, [Msg | Args]);
+        _ -> ok
+    end,
     case maps:get(to_local_topic, Vars, undefined) of
         undefined -> ok;
         _Topic ->

apps/emqx_connector/src/mqtt/emqx_connector_mqtt_schema.erl

@@ -21,7 +21,12 @@
 -behaviour(hocon_schema).
 
 -export([ roots/0
-        , fields/1]).
+        , fields/1
+        ]).
+
+-export([ ingress_desc/0
+        , egress_desc/0
+        ]).
 
 -import(emqx_schema, [mk_duration/2]).
 
@@ -29,6 +34,10 @@ roots() ->
     fields("config").
 
 fields("config") ->
+    fields("connector") ++
+    topic_mappings();
+
+fields("connector") ->
     [ {server,
         sc(emqx_schema:ip_port(),
            #{ default => "127.0.0.1:1883"
@@ -76,31 +85,6 @@ fields("config") ->
         sc(ref("replayq"),
            #{ desc => """
 Queue messages in disk files.
-"""
-            })}
-    , {ingress,
-        sc(ref("ingress"),
-           #{ default => #{}
-            , desc => """
-The ingress config defines how this bridge receive messages from the remote MQTT broker, and then
-send them to the local broker.<br>
-Template with variables is allowed in 'to_local_topic', 'subscribe_qos', 'qos', 'retain',
-'payload'.<br>
-NOTE: if this bridge is used as the input of a rule (emqx rule engine), and also to_local_topic is
-configured, then messages got from the remote broker will be sent to both the 'to_local_topic' and
-the rule.
-"""
-            })}
-    , {egress,
-        sc(ref("egress"),
-           #{ default => #{}
-            , desc => """
-The egress config defines how this bridge forwards messages from the local broker to the remote
-broker.<br>
-Template with variables is allowed in 'to_remote_topic', 'qos', 'retain', 'payload'.<br>
-NOTE: if this bridge is used as the output of a rule (emqx rule engine), and also from_local_topic
-is configured, then both the data got from the rule and the MQTT messages that matches
-from_local_topic will be forwarded.
 """
             })}
     ] ++ emqx_connector_schema_lib:ssl_fields();
@@ -122,6 +106,12 @@ fields("ingress") ->
            #{ desc => """
 Send messages to which topic of the local broker.<br>
 Template with variables is allowed.
+"""
+            })}
+    , {hookpoint,
+        sc(binary(),
+           #{ desc => """
+The hookpoint will be triggered when there's any message received from the remote broker.
 """
             })}
     ] ++ common_inout_confs();
@@ -170,6 +160,38 @@ the memory cache reaches 'seg_bytes'.
             })}
     ].
 
+topic_mappings() ->
+    [ {ingress,
+        sc(ref("ingress"),
+           #{ default => #{}
+            , desc => ingress_desc()
+            })}
+    , {egress,
+        sc(ref("egress"),
+           #{ default => #{}
+            , desc => egress_desc()
+            })}
+    ].
+
+ingress_desc() -> """
+The ingress config defines how this bridge receive messages from the remote MQTT broker, and then
+send them to the local broker.<br>
+Template with variables is allowed in 'to_local_topic', 'subscribe_qos', 'qos', 'retain',
+'payload'.<br>
+NOTE: if this bridge is used as the input of a rule (emqx rule engine), and also to_local_topic is
+configured, then messages got from the remote broker will be sent to both the 'to_local_topic' and
+the rule.
+""".
+
+egress_desc() -> """
+The egress config defines how this bridge forwards messages from the local broker to the remote
+broker.<br>
+Template with variables is allowed in 'to_remote_topic', 'qos', 'retain', 'payload'.<br>
+NOTE: if this bridge is used as the output of a rule (emqx rule engine), and also from_local_topic
+is configured, then both the data got from the rule and the MQTT messages that matches
+from_local_topic will be forwarded.
+""".
+
 common_inout_confs() ->
     [ {qos,
         sc(qos(),

apps/emqx_connector/src/mqtt/emqx_connector_mqtt_worker.erl

@@ -381,7 +381,7 @@ pop_and_send_loop(#{replayq := Q} = State, N) ->
 
 do_send(#{connect_opts := #{forwards := undefined}}, _QAckRef, Msg) ->
     ?SLOG(error, #{msg => "cannot forward messages to remote broker"
-                          " as forwards is not configured",
+                          " as 'egress' is not configured",
                    messages => Msg});
 do_send(#{inflight := Inflight,
           connection := Connection,

apps/emqx_rule_engine/src/emqx_rule_events.erl

@@ -68,7 +68,7 @@ reload() ->
             ok = emqx_rule_engine:load_hooks_for_rule(Rule)
         end, emqx_rule_engine:get_rules()).
 
-load(<<"$bridges/", _ChannelId/binary>> = BridgeTopic) ->
+load(<<"$bridges/", _BridgeId/binary>> = BridgeTopic) ->
     emqx_hooks:put(BridgeTopic, {?MODULE, on_bridge_message_received,
         [#{bridge_topic => BridgeTopic}]});
 load(Topic) ->