fix(config): start the top level config handler at emqx bootup

apps/emqx/src/emqx_config_handler.erl

@@ -23,7 +23,7 @@
 -export([ start_link/0
         , start_handler/3
         , update_config/2
-        , child_spec/2
+        , child_spec/3
         ]).
 
 %% emqx_config_handler callbacks
@@ -40,7 +40,7 @@
 
 -type config() :: term().
 -type config_map() :: #{atom() => config()} | [config_map()].
--type handler_name() :: module().
+-type handler_name() :: module() | top.
 -type key_path() :: [atom()].
 
 -optional_callbacks([handle_update_config/2]).
@@ -61,10 +61,10 @@ start_link() ->
 start_handler(HandlerName, Parent, ConfKeyPath) ->
     gen_server:start_link({local, HandlerName}, ?MODULE, {HandlerName, Parent, ConfKeyPath}, []).
 
--spec child_spec(module(), key_path()) -> supervisor:child_spec().
+-spec child_spec(module(), handler_name(), key_path()) -> supervisor:child_spec().
-child_spec(Mod, KeyPath) ->
+child_spec(Mod, Parent, KeyPath) ->
     #{id => Mod,
-      start => {?MODULE, start_handler, [Mod, ?MODULE, KeyPath]},
+      start => {?MODULE, start_handler, [Mod, Parent, KeyPath]},
       restart => permanent,
       type => worker,
       modules => [?MODULE]}.

apps/emqx/src/emqx_kernel_sup.erl

@@ -33,7 +33,9 @@ init([]) ->
            child_spec(emqx_stats, worker),
            child_spec(emqx_metrics, worker),
            child_spec(emqx_ctl, worker),
-           child_spec(emqx_zone, worker)]}}.
+           child_spec(emqx_zone, worker),
+           child_spec(emqx_config_handler, worker)
+          ]}}.
 
 child_spec(M, Type) ->
     child_spec(M, Type, []).

apps/emqx_data_bridge/src/emqx_data_bridge_sup.erl

@@ -36,7 +36,8 @@ init([]) ->
           restart => permanent,
           type => worker,
           modules => [emqx_data_bridge_monitor]},
-        emqx_config_handler:child_spec(emqx_data_bridge_config_handler, config_key_path())
+        emqx_config_handler:child_spec(emqx_data_bridge_config_handler, emqx_config_handler,
+            config_key_path())
     ],
     {ok, {SupFlags, ChildSpecs}}.
 

apps/emqx_resource/src/emqx_resource_instance.erl

@@ -90,16 +90,6 @@ create_local(InstId, ResourceType, InstConf) ->
         Error -> Error
     end.
 
-save_config_to_disk(InstId, ResourceType, Config) ->
-    %% TODO: send an event to the config handler, and the hander (single process)
-    %% will dump configs for all instances (from an ETS table) to a file.
-    file:write_file(filename:join([emqx_data_dir(), binary_to_list(InstId) ++ ".conf"]),
-        jsx:encode(#{id => InstId, resource_type => ResourceType,
-                     config => emqx_resource:call_jsonify(ResourceType, Config)})).
-
-emqx_data_dir() ->
-    "data".
-
 %%------------------------------------------------------------------------------
 %% gen_server callbacks
 %%------------------------------------------------------------------------------
@@ -180,13 +170,7 @@ do_create(InstId, ResourceType, Config) ->
                         #{mod => ResourceType, config => Config,
                           state => ResourceState, status => stopped}}),
                     _ = do_health_check(InstId),
-                    case save_config_to_disk(InstId, ResourceType, Config) of
+                    {ok, force_lookup(InstId)};
-                        ok -> {ok, force_lookup(InstId)};
-                        {error, Reason} ->
-                            logger:error("save config for ~p resource ~p to disk failed: ~p",
-                                [ResourceType, InstId, Reason]),
-                            {error, Reason}
-                    end;
                 {error, Reason} ->
                     logger:error("start ~s resource ~s failed: ~p", [ResourceType, InstId, Reason]),
                     {error, Reason}