diff --git a/.github/workflows/run_cts_tests.yaml b/.github/workflows/run_cts_tests.yaml
index bfa1d1394..487d8fae7 100644
--- a/.github/workflows/run_cts_tests.yaml
+++ b/.github/workflows/run_cts_tests.yaml
@@ -50,7 +50,7 @@ jobs:
           printenv > .env
           docker exec -i erlang sh -c "make ensure-rebar3"
           docker exec -i erlang sh -c "./rebar3 eunit --application=emqx_auth_ldap"
-          docker exec --env-file .env -i erlang sh -c "./rebar3 ct --dir apps/emqx_auth_ldap"
+          docker exec --env-file .env -i erlang sh -c "make apps/emqx_auth_ldap-ct"
       - uses: actions/upload-artifact@v1
         if: failure()
         with:
@@ -120,7 +120,7 @@ jobs:
           printenv > .env
           docker exec -i erlang sh -c "make ensure-rebar3"
           docker exec -i erlang sh -c "./rebar3 eunit --application=emqx_auth_mongo"
-          docker exec --env-file .env -i erlang sh -c "./rebar3 ct --dir apps/emqx_auth_mongo"
+          docker exec --env-file .env -i erlang sh -c "make apps/emqx_auth_mongo-ct"
       - uses: actions/upload-artifact@v1
         if: failure()
         with:
@@ -203,7 +203,7 @@ jobs:
           printenv > .env
           docker exec -i erlang sh -c "make ensure-rebar3"
           docker exec -i erlang sh -c "./rebar3 eunit --application=emqx_auth_mysql"
-          docker exec --env-file .env -i erlang sh -c "./rebar3 ct --dir apps/emqx_auth_mysql"
+          docker exec --env-file .env -i erlang sh -c "make apps/emqx_auth_mysql-ct"
       - uses: actions/upload-artifact@v1
         if: failure()
         with:
@@ -278,7 +278,7 @@ jobs:
           printenv > .env
           docker exec -i erlang sh -c "make ensure-rebar3"
           docker exec -i erlang sh -c "./rebar3 eunit --application=emqx_auth_pgsql"
-          docker exec --env-file .env -i erlang sh -c "./rebar3 ct --dir apps/emqx_auth_pgsql"
+          docker exec --env-file .env -i erlang sh -c "make apps/emqx_auth_pgsql-ct"
       - uses: actions/upload-artifact@v1
         if: failure()
         with:
@@ -399,7 +399,7 @@ jobs:
           printenv > .env
           docker exec -i erlang sh -c "make ensure-rebar3"
           docker exec -i erlang sh -c "./rebar3 eunit --application=emqx_auth_redis"
-          docker exec --env-file .env -i erlang sh -c "./rebar3 ct --dir apps/emqx_auth_redis"
+          docker exec --env-file .env -i erlang sh -c "make apps/emqx_auth_redis-ct"
       - uses: actions/upload-artifact@v1
         if: failure()
         with:
diff --git a/apps/emqx/etc/emqx.conf b/apps/emqx/etc/emqx.conf
index f6627bf1c..d2b5fd11d 100644
--- a/apps/emqx/etc/emqx.conf
+++ b/apps/emqx/etc/emqx.conf
@@ -203,6 +203,11 @@ node.cookie = "emqxsecretcookie"
 ## Value: Folder
 node.data_dir = "{{ platform_data_dir }}"
 
+## The config file dir for the node
+##
+## Value: Folder
+node.etc_dir = "{{ platform_etc_dir }}"
+
 ## Heartbeat monitoring of an Erlang runtime system. Comment the line to disable
 ## heartbeat, or set the value as 'on'
 ##
@@ -457,8 +462,8 @@ log.file = emqx.log
 ## and Erlang process message queue inspection.
 ##
 ## Value: Integer or 'unlimited' (without quotes)
-## Default: 20
-#log.max_depth = 20
+## Default: 80
+#log.max_depth = 80
 
 ## Log formatter
 ## Value: text | json
diff --git a/apps/emqx/rebar.config b/apps/emqx/rebar.config
index 5d48e06a3..22f31a345 100644
--- a/apps/emqx/rebar.config
+++ b/apps/emqx/rebar.config
@@ -16,7 +16,7 @@
     , {ekka, {git, "https://github.com/emqx/ekka", {tag, "0.10.2"}}}
     , {gen_rpc, {git, "https://github.com/emqx/gen_rpc", {tag, "2.5.1"}}}
     , {cuttlefish, {git, "https://github.com/emqx/cuttlefish", {tag, "v4.0.1"}}} %% todo delete when plugins use hocon
-    , {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.7.0"}}}
+    , {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.9.0"}}}
     , {pbkdf2, {git, "https://github.com/emqx/erlang-pbkdf2.git", {branch, "2.0.4"}}}
     , {recon, {git, "https://github.com/ferd/recon", {tag, "2.5.1"}}}
     , {snabbkaffe, {git, "https://github.com/kafka4beam/snabbkaffe.git", {tag, "0.13.0"}}}
@@ -28,9 +28,8 @@
    {test,
        [{deps,
            [ meck
-           , {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.6.0"}}}
            , {bbmustache,"1.10.0"}
-           , {emqx_ct_helpers, {git,"https://github.com/zmstone/emqx-ct-helpers", {branch,"hocon"}}}
+           , {emqx_ct_helpers, {git,"https://github.com/emqx/emqx-ct-helpers", {branch,"hocon"}}}
            , {emqtt, {git, "https://github.com/emqx/emqtt", {tag, "1.2.3.1"}}}
            ]},
          {extra_src_dirs, [{"test",[recursive]}]}
diff --git a/apps/emqx/rebar3 b/apps/emqx/rebar3
new file mode 100755
index 000000000..edb85b3c9
Binary files /dev/null and b/apps/emqx/rebar3 differ
diff --git a/apps/emqx/src/emqx_config.erl b/apps/emqx/src/emqx_config.erl
index d05486328..61423f9af 100644
--- a/apps/emqx/src/emqx_config.erl
+++ b/apps/emqx/src/emqx_config.erl
@@ -23,6 +23,8 @@
         , put/2
         , deep_get/3
         , deep_put/3
+        , safe_atom_key_map/1
+        , unsafe_atom_key_map/1
         ]).
 
 -spec get() -> term().
@@ -58,3 +60,21 @@ deep_put([], Map, Config) when is_map(Map) ->
 deep_put([Key | KeyPath], Map, Config) ->
     SubMap = deep_put(KeyPath, maps:get(Key, Map, #{}), Config),
     Map#{Key => SubMap}.
+
+unsafe_atom_key_map(Map) ->
+    covert_keys_to_atom(Map, fun(K) -> binary_to_atom(K, utf8) end).
+
+safe_atom_key_map(Map) ->
+    covert_keys_to_atom(Map, fun(K) -> binary_to_existing_atom(K, utf8) end).
+
+covert_keys_to_atom(BinKeyMap, Conv) when is_map(BinKeyMap) ->
+    maps:fold(
+        fun(K, V, Acc) when is_binary(K) ->
+              Acc#{Conv(K) => covert_keys_to_atom(V, Conv)};
+           (K, V, Acc) when is_atom(K) ->
+              %% richmap keys
+              Acc#{K => covert_keys_to_atom(V, Conv)}
+        end, #{}, BinKeyMap);
+covert_keys_to_atom(ListV, Conv) when is_list(ListV) ->
+    [covert_keys_to_atom(V, Conv) || V <- ListV];
+covert_keys_to_atom(Val, _) -> Val.
diff --git a/apps/emqx/src/emqx_config_handler.erl b/apps/emqx/src/emqx_config_handler.erl
index 248847177..20aa0b5f8 100644
--- a/apps/emqx/src/emqx_config_handler.erl
+++ b/apps/emqx/src/emqx_config_handler.erl
@@ -17,13 +17,16 @@
 %% And there are a top level config handler maintains the overall config map.
 -module(emqx_config_handler).
 
+-include("logger.hrl").
+
 -behaviour(gen_server).
 
 %% API functions
 -export([ start_link/0
-        , start_handler/3
+        , add_handler/2
         , update_config/2
-        , child_spec/3
+        , get_raw_config/0
+        , merge_to_old_config/2
         ]).
 
 %% emqx_config_handler callbacks
@@ -38,74 +41,74 @@
          terminate/2,
          code_change/3]).
 
--type config() :: term().
--type config_map() :: #{atom() => config()} | [config_map()].
--type handler_name() :: module() | top.
--type key_path() :: [atom()].
+-define(MOD, {mod}).
+
+-type update_request() :: term().
+-type raw_config() :: hocon:config() | undefined.
+-type config_key() :: atom().
+-type handler_name() :: module().
+-type config_key_path() :: [atom()].
+-type handlers() :: #{config_key() => handlers(), ?MOD => handler_name()}.
 
 -optional_callbacks([handle_update_config/2]).
 
--callback handle_update_config(config(), config_map()) -> config_map().
+-callback handle_update_config(update_request(), raw_config()) -> update_request().
 
--record(state, {
-    handler_name :: handler_name(),
-    parent :: handler_name(),
-    key_path :: key_path()
-}).
+-type state() :: #{
+    handlers := handlers(),
+    raw_config := raw_config(),
+    atom() => term()
+}.
 
 start_link() ->
-    start_handler(?MODULE, top, []).
+    gen_server:start_link({local, ?MODULE}, ?MODULE, {}, []).
 
--spec start_handler(handler_name(), handler_name(), key_path()) ->
-    {ok, pid()} | {error, {already_started, pid()}} | {error, term()}.
-start_handler(HandlerName, Parent, ConfKeyPath) ->
-    gen_server:start_link({local, HandlerName}, ?MODULE, {HandlerName, Parent, ConfKeyPath}, []).
+-spec update_config(config_key_path(), update_request()) -> ok | {error, term()}.
+update_config(ConfKeyPath, UpdateReq) ->
+    gen_server:call(?MODULE, {update_config, ConfKeyPath, UpdateReq}).
 
--spec child_spec(module(), handler_name(), key_path()) -> supervisor:child_spec().
-child_spec(Mod, Parent, KeyPath) ->
-    #{id => Mod,
-      start => {?MODULE, start_handler, [Mod, Parent, KeyPath]},
-      restart => permanent,
-      type => worker,
-      modules => [?MODULE]}.
+-spec add_handler(config_key_path(), handler_name()) -> ok.
+add_handler(ConfKeyPath, HandlerName) ->
+    gen_server:call(?MODULE, {add_child, ConfKeyPath, HandlerName}).
 
--spec update_config(handler_name(), config()) -> ok.
-update_config(top, Config) ->
-    emqx_config:put(Config),
-    save_config_to_disk(Config);
-update_config(Handler, Config) ->
-    case is_process_alive(whereis(Handler)) of
-        true -> gen_server:cast(Handler, {handle_update_config, Config});
-        false -> error({not_alive, Handler})
-    end.
+-spec get_raw_config() -> raw_config().
+get_raw_config() ->
+    gen_server:call(?MODULE, get_raw_config).
 
 %%============================================================================
-%% callbacks of emqx_config_handler (the top-level handler)
-handle_update_config(Config, undefined) ->
-    handle_update_config(Config, #{});
-handle_update_config(Config, OldConfigMap) ->
-    %% simply merge the config to the overall config
-    maps:merge(OldConfigMap, Config).
 
-init({HandlerName, Parent, ConfKeyPath}) ->
-    {ok, #state{handler_name = HandlerName, parent = Parent, key_path = ConfKeyPath}}.
+-spec init(term()) -> {ok, state()}.
+init(_) ->
+    {ok, RawConf} = hocon:load(emqx_conf_name(), #{format => richmap}),
+    {_MappedEnvs, Conf} = hocon_schema:map_translate(emqx_schema, RawConf, #{}),
+    ok = save_config_to_emqx_config(Conf),
+    {ok, #{raw_config => hocon_schema:richmap_to_map(RawConf),
+           handlers => #{?MOD => ?MODULE}}}.
+
+handle_call(get_raw_config, _From, State = #{raw_config := RawConf}) ->
+    {reply, RawConf, State};
+
+handle_call({add_child, ConfKeyPath, HandlerName}, _From,
+            State = #{handlers := Handlers}) ->
+    {reply, ok, State#{handlers =>
+        emqx_config:deep_put(ConfKeyPath, Handlers, #{?MOD => HandlerName})}};
+
+handle_call({update_config, ConfKeyPath, UpdateReq}, _From,
+        #{raw_config := RawConf, handlers := Handlers} = State) ->
+    try {RootKeys, Conf} = do_update_config(ConfKeyPath, Handlers, RawConf, UpdateReq),
+        {reply, save_configs(RootKeys, Conf), State#{raw_config => Conf}}
+    catch
+        throw: Reason ->
+            {reply, {error, Reason}, State};
+        Error : Reason : ST ->
+            ?LOG(error, "update config failed: ~p", [{Error, Reason, ST}]),
+            {reply, {error, Reason}, State}
+    end;
 
 handle_call(_Request, _From, State) ->
     Reply = ok,
     {reply, Reply, State}.
 
-handle_cast({handle_update_config, Config}, #state{handler_name = HandlerName,
-        parent = Parent, key_path = ConfKeyPath} = State) ->
-    %% accumulate the config map of this config handler
-    OldConfigMap = emqx_config:get(ConfKeyPath, undefined),
-    SubConfigMap = case erlang:function_exported(HandlerName, handle_update_config, 2) of
-        true -> HandlerName:handle_update_config(Config, OldConfigMap);
-        false -> wrap_sub_config(ConfKeyPath, Config)
-    end,
-    %% then notify the parent handler
-    update_config(Parent, SubConfigMap),
-    {noreply, State};
-
 handle_cast(_Msg, State) ->
     {noreply, State}.
 
@@ -118,17 +121,100 @@ terminate(_Reason, _State) ->
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
-%%============================================================================
-save_config_to_disk(ConfigMap) ->
-    Filename = filename:join([emqx_data_dir(), "emqx_override.conf"]),
-    case file:write_file(Filename, jsx:encode(ConfigMap)) of
-        ok -> ok;
-        {error, Reason} -> logger:error("write to ~s failed, ~p", [Filename, Reason])
+do_update_config([], Handlers, OldConf, UpdateReq) ->
+    call_handle_update_config(Handlers, OldConf, UpdateReq);
+do_update_config([ConfKey | ConfKeyPath], Handlers, OldConf, UpdateReq) ->
+    SubOldConf = get_sub_config(ConfKey, OldConf),
+    case maps:find(ConfKey, Handlers) of
+        error -> throw({handler_not_found, ConfKey});
+        {ok, SubHandlers} ->
+            NewUpdateReq = do_update_config(ConfKeyPath, SubHandlers, SubOldConf, UpdateReq),
+            call_handle_update_config(Handlers, OldConf, #{bin(ConfKey) => NewUpdateReq})
     end.
 
-emqx_data_dir() ->
-    %emqx_config:get([node, data_dir])
-    "data".
+get_sub_config(_, undefined) ->
+    undefined;
+get_sub_config(ConfKey, OldConf) when is_map(OldConf) ->
+    maps:get(bin(ConfKey), OldConf, undefined);
+get_sub_config(_, OldConf) ->
+    OldConf.
 
-wrap_sub_config(ConfKeyPath, Config) ->
-    emqx_config:deep_put(ConfKeyPath, #{}, Config).
+call_handle_update_config(Handlers, OldConf, UpdateReq) ->
+    HandlerName = maps:get(?MOD, Handlers, undefined),
+    case erlang:function_exported(HandlerName, handle_update_config, 2) of
+        true -> HandlerName:handle_update_config(UpdateReq, OldConf);
+        false -> UpdateReq %% the default behaviour is overwriting the old config
+    end.
+
+%% callbacks for the top-level handler
+handle_update_config(UpdateReq, OldConf) ->
+    FullRawConf = merge_to_old_config(UpdateReq, OldConf),
+    {maps:keys(UpdateReq), FullRawConf}.
+
+%% default callback of config handlers
+merge_to_old_config(UpdateReq, undefined) ->
+    merge_to_old_config(UpdateReq, #{});
+merge_to_old_config(UpdateReq, RawConf) ->
+    maps:merge(RawConf, UpdateReq).
+
+%%============================================================================
+save_configs(RootKeys, Conf0) ->
+    {_MappedEnvs, Conf1} = hocon_schema:map_translate(emqx_schema, to_richmap(Conf0), #{}),
+    %save_config_to_app_env(MappedEnvs),
+    save_config_to_emqx_config(hocon_schema:richmap_to_map(Conf1)),
+    save_config_to_disk(RootKeys, Conf0).
+
+%% We may need also support hot config update for the apps that use application envs.
+%% If so uncomment the following lines to update the configs to application env
+% save_config_to_app_env(MappedEnvs) ->
+%     lists:foreach(fun({AppName, Envs}) ->
+%             [application:set_env(AppName, Par, Val) || {Par, Val} <- Envs]
+%         end, MappedEnvs).
+
+save_config_to_emqx_config(Conf) ->
+    emqx_config:put(emqx_config:unsafe_atom_key_map(Conf)).
+
+save_config_to_disk(RootKeys, Conf) ->
+    FileName = emqx_override_conf_name(),
+    OldConf = read_old_config(FileName),
+    %% We don't save the overall config to file, but only the sub configs
+    %% under RootKeys
+    write_new_config(FileName,
+        maps:merge(OldConf, maps:with(RootKeys, Conf))).
+
+write_new_config(FileName, Conf) ->
+    case file:write_file(FileName, jsx:prettify(jsx:encode(Conf))) of
+        ok -> ok;
+        {error, Reason} ->
+            logger:error("write to ~s failed, ~p", [FileName, Reason]),
+            {error, Reason}
+    end.
+
+read_old_config(FileName) ->
+    case file:read_file(FileName) of
+        {ok, Text} ->
+            try jsx:decode(Text, [{return_maps, true}]) of
+                Conf when is_map(Conf) -> Conf;
+                _ -> #{}
+            catch _Err : _Reason ->
+                #{}
+            end;
+        _ -> #{}
+    end.
+
+emqx_conf_name() ->
+    filename:join([etc_dir(), "emqx.conf"]).
+
+emqx_override_conf_name() ->
+    filename:join([emqx:get_env(data_dir), "emqx_override.conf"]).
+
+etc_dir() ->
+    emqx:get_env(etc_dir).
+
+to_richmap(Map) ->
+    {ok, RichMap} = hocon:binary(jsx:encode(Map), #{format => richmap}),
+    RichMap.
+
+bin(A) when is_atom(A) -> list_to_binary(atom_to_list(A));
+bin(B) when is_binary(B) -> B;
+bin(S) when is_list(S) -> list_to_binary(S).
diff --git a/apps/emqx/src/emqx_plugins.erl b/apps/emqx/src/emqx_plugins.erl
index bda537f47..2f39edcb4 100644
--- a/apps/emqx/src/emqx_plugins.erl
+++ b/apps/emqx/src/emqx_plugins.erl
@@ -30,8 +30,6 @@
         , reload/1
         , list/0
         , find_plugin/1
-        , generate_configs/1
-        , apply_configs/1
         ]).
 
 -export([funlog/2]).
@@ -173,15 +171,7 @@ load_ext_plugin(PluginDir) ->
                       ?LOG(alert, "plugin_app_file_not_found: ~s", [AppFile]),
                       error({plugin_app_file_not_found, AppFile})
               end,
-    ok = load_plugin_app(AppName, Ebin),
-    try
-        ok = generate_configs(AppName, PluginDir)
-    catch
-        throw : {conf_file_not_found, ConfFile} ->
-            %% this is maybe a dependency of an external plugin
-            ?LOG(debug, "config_load_error_ignored for app=~p, path=~s", [AppName, ConfFile]),
-            ok
-    end.
+    load_plugin_app(AppName, Ebin).
 
 load_plugin_app(AppName, Ebin) ->
     _ = code:add_patha(Ebin),
@@ -246,7 +236,6 @@ plugin(AppName, Type) ->
 
 load_plugin(Name, Persistent) ->
     try
-        ok = ?MODULE:generate_configs(Name),
         case load_app(Name) of
             ok ->
                 start_app(Name, fun(App) -> plugin_loaded(App, Persistent) end);
@@ -362,77 +351,5 @@ plugin_type(backend) -> backend;
 plugin_type(bridge) -> bridge;
 plugin_type(_) -> feature.
 
-
 funlog(Key, Value) ->
     ?LOG(info, "~s = ~p", [string:join(Key, "."), Value]).
-
-generate_configs(App) ->
-    PluginConfDir = emqx:get_env(plugins_etc_dir),
-    PluginSchemaDir = code:priv_dir(App),
-    generate_configs(App, PluginConfDir, PluginSchemaDir).
-
-generate_configs(App, PluginDir) ->
-    PluginConfDir = filename:join([PluginDir, "etc"]),
-    PluginSchemaDir = filename:join([PluginDir, "priv"]),
-    generate_configs(App, PluginConfDir, PluginSchemaDir).
-
-generate_configs(App, PluginConfDir, PluginSchemaDir) ->
-    ConfigFile = filename:join([PluginConfDir, App]) ++ ".config",
-    case filelib:is_file(ConfigFile) of
-        true ->
-            {ok, [Configs]} = file:consult(ConfigFile),
-            apply_configs(Configs);
-        false ->
-            SchemaFile = filename:join([PluginSchemaDir, App]) ++ ".schema",
-            case filelib:is_file(SchemaFile) of
-                true ->
-                    AppsEnv = do_generate_configs(App),
-                    apply_configs(AppsEnv);
-                false ->
-                    SchemaMod = lists:concat([App, "_schema"]),
-                    ConfName = filename:join([PluginConfDir, App]) ++ ".conf",
-                    SchemaFile1 = filename:join([code:lib_dir(App), "ebin", SchemaMod]) ++ ".beam",
-                    do_generate_hocon_configs(App, ConfName, SchemaFile1)
-            end
-    end.
-
-do_generate_configs(App) ->
-    Name1 = filename:join([emqx:get_env(plugins_etc_dir), App]) ++ ".conf",
-    Name2 = filename:join([code:lib_dir(App), "etc", App]) ++ ".conf",
-    ConfFile = case {filelib:is_file(Name1), filelib:is_file(Name2)} of
-                   {true, _} -> Name1;
-                   {false, true} -> Name2;
-                   {false, false} -> error({config_not_found, [Name1, Name2]})
-               end,
-    SchemaFile = filename:join([code:priv_dir(App), App]) ++ ".schema",
-    case filelib:is_file(SchemaFile) of
-        true ->
-            Schema = cuttlefish_schema:files([SchemaFile]),
-            Conf = cuttlefish_conf:file(ConfFile),
-            cuttlefish_generator:map(Schema, Conf, undefined, fun ?MODULE:funlog/2);
-        false ->
-            error({schema_not_found, SchemaFile})
-    end.
-
-do_generate_hocon_configs(App, ConfName, SchemaFile) ->
-    SchemaMod = lists:concat([App, "_schema"]),
-    case {filelib:is_file(ConfName), filelib:is_file(SchemaFile)} of
-        {true, true} ->
-            {ok, RawConfig} = hocon:load(ConfName, #{format => richmap}),
-            Config = hocon_schema:check(list_to_atom(SchemaMod), RawConfig, #{atom_key => true,
-                                                                              return_plain => true}),
-            emqx_config_handler:update_config(emqx_config_handler, Config);
-        {true, false} ->
-            error({schema_not_found, [SchemaFile]});
-        {false, true} ->
-            error({config_not_found, [ConfName]});
-        {false, false} ->
-            error({conf_and_schema_not_found, [ConfName, SchemaFile]})
-    end.
-
-apply_configs([]) ->
-    ok;
-apply_configs([{App, Config} | More]) ->
-    lists:foreach(fun({Key, _}) -> application:unset_env(App, Key) end, application:get_all_env(App)),
-    lists:foreach(fun({Key, Val}) -> application:set_env(App, Key, Val) end, Config),
-    apply_configs(More).
diff --git a/apps/emqx/src/emqx_schema.erl b/apps/emqx/src/emqx_schema.erl
index cb631ea22..d090f26f1 100644
--- a/apps/emqx/src/emqx_schema.erl
+++ b/apps/emqx/src/emqx_schema.erl
@@ -50,9 +50,22 @@
 -export([conf_get/2, conf_get/3, keys/2, filter/1]).
 -export([ssl/2, tr_ssl/2, tr_password_hash/2]).
 
+%% will be used by emqx_ct_helper to find the dependent apps
+-export([includes/0]).
+
 structs() -> ["cluster", "node", "rpc", "log", "lager",
               "acl", "mqtt", "zone", "listener", "module", "broker",
-              "plugins", "sysmon", "os_mon", "vm_mon", "alarm", "telemetry"].
+              "plugins", "sysmon", "os_mon", "vm_mon", "alarm", "telemetry"]
+             ++ includes().
+
+-ifdef(TEST).
+includes() ->[].
+-else.
+includes() ->
+    [ "emqx_data_bridge"
+    , "emqx_telemetry"
+    ].
+-endif.
 
 fields("cluster") ->
     [ {"name", t(atom(), "ekka.cluster_name", emqxcl)}
@@ -119,6 +132,7 @@ fields("node") ->
                                        override_env => "EMQX_NODE_COOKIE"
                                       })}
     , {"data_dir", t(string(), "emqx.data_dir", undefined)}
+    , {"etc_dir", t(string(), "emqx.etc_dir", undefined)}
     , {"heartbeat", t(flag(), undefined, false)}
     , {"async_threads", t(range(1, 1024), "vm_args.+A", undefined)}
     , {"process_limit", t(integer(), "vm_args.+P", undefined)}
@@ -163,7 +177,7 @@ fields("log") ->
     , {"chars_limit", t(integer(), undefined, -1)}
     , {"supervisor_reports", t(union([error, progress]), undefined, error)}
     , {"max_depth", t(union([infinity, integer()]),
-                      "kernel.error_logger_format_depth", 20)}
+                      "kernel.error_logger_format_depth", 80)}
     , {"formatter", t(union([text, json]), undefined, text)}
     , {"single_line", t(boolean(), undefined, true)}
     , {"rotation", ref("rotation")}
@@ -467,8 +481,11 @@ fields("telemetry") ->
     [ {"enabled", t(boolean(), undefined, false)}
     , {"url", t(string(), undefined, "https://telemetry-emqx-io.bigpar.vercel.app/api/telemetry")}
     , {"report_interval", t(duration_s(), undefined, "7d")}
-    ].
+    ];
 
+fields(ExtraField) ->
+    Mod = list_to_atom(ExtraField),
+    Mod:fields(ExtraField).
 
 translations() -> ["ekka", "vm_args", "gen_rpc", "kernel", "emqx"].
 
diff --git a/apps/emqx_data_bridge/src/emqx_data_bridge.erl b/apps/emqx_data_bridge/src/emqx_data_bridge.erl
index 2c5b52d8e..fe2900b7f 100644
--- a/apps/emqx_data_bridge/src/emqx_data_bridge.erl
+++ b/apps/emqx_data_bridge/src/emqx_data_bridge.erl
@@ -22,14 +22,44 @@
         , resource_id_to_name/1
         , list_bridges/0
         , is_bridge/1
+        , config_key_path/0
+        , update_config/1
         ]).
 
+-export([structs/0, fields/1]).
+
+%%======================================================================================
+%% Hocon Schema Definitions
+
+-define(BRIDGE_FIELDS(T),
+    [{name, hoconsc:t(typerefl:binary())},
+     {type, hoconsc:t(typerefl:atom(T))},
+     {config, hoconsc:t(hoconsc:ref(list_to_atom("emqx_connector_"++atom_to_list(T)), ""))}]).
+
+-define(TYPES, [mysql, pgsql, mongo, redis, ldap]).
+-define(BRIDGES, [hoconsc:ref(?MODULE, T) || T <- ?TYPES]).
+
+structs() -> ["emqx_data_bridge"].
+
+fields("emqx_data_bridge") ->
+    [{bridges, #{type => hoconsc:array(hoconsc:union(?BRIDGES)),
+                 default => []}}];
+
+fields(mysql) -> ?BRIDGE_FIELDS(mysql);
+fields(pgsql) -> ?BRIDGE_FIELDS(pgsql);
+fields(mongo) -> ?BRIDGE_FIELDS(mongo);
+fields(redis) -> ?BRIDGE_FIELDS(redis);
+fields(ldap) -> ?BRIDGE_FIELDS(ldap).
+
+%%======================================================================================
+
 load_bridges() ->
-    ConfFile = filename:join([emqx:get_env(plugins_etc_dir), ?MODULE]) ++ ".conf",
-    {ok, RawConfig} = hocon:load(ConfFile, #{format => richmap}),
-    #{emqx_data_bridge := #{bridges := Bridges}} =
-        hocon_schema:check(emqx_data_bridge_schema, RawConfig,
-            #{atom_key => true, return_plain => true}),
+    % ConfFile = filename:join([emqx:get_env(plugins_etc_dir), ?MODULE]) ++ ".conf",
+    % {ok, RawConfig} = hocon:load(ConfFile, #{format => richmap}),
+    % #{emqx_data_bridge := #{bridges := Bridges}} =
+    %     hocon_schema:check(emqx_data_bridge_schema, RawConfig,
+    %         #{atom_key => true, return_plain => true}),
+    Bridges = emqx_config:get([emqx_data_bridge, bridges], []),
     emqx_data_bridge_monitor:ensure_all_started(Bridges).
 
 resource_type(mysql) -> emqx_connector_mysql;
@@ -57,3 +87,9 @@ is_bridge(#{id := <<"bridge:", _/binary>>}) ->
     true;
 is_bridge(_Data) ->
     false.
+
+config_key_path() ->
+    [emqx_data_bridge, bridges].
+
+update_config(ConfigReq) ->
+    emqx_config_handler:update_config(config_key_path(), ConfigReq).
diff --git a/apps/emqx_data_bridge/src/emqx_data_bridge_api.erl b/apps/emqx_data_bridge/src/emqx_data_bridge_api.erl
index c0992fc46..7b1b4981d 100644
--- a/apps/emqx_data_bridge/src/emqx_data_bridge_api.erl
+++ b/apps/emqx_data_bridge/src/emqx_data_bridge_api.erl
@@ -57,6 +57,8 @@
         , delete_bridge/2
         ]).
 
+-define(BRIDGE(N, T, C), #{<<"name">> => N, <<"type">> => T, <<"config">> => C}).
+
 list_bridges(_Binding, _Params) ->
     {200, #{code => 0, data => [format_api_reply(Data) ||
         Data <- emqx_data_bridge:list_bridges()]}}.
@@ -74,10 +76,9 @@ create_bridge(#{name := Name}, Params) ->
     BridgeType = proplists:get_value(<<"type">>, Params),
     case emqx_resource:check_and_create(
             emqx_data_bridge:name_to_resource_id(Name),
-            emqx_data_bridge:resource_type(BridgeType), Config) of
+            emqx_data_bridge:resource_type(atom(BridgeType)), maps:from_list(Config)) of
         {ok, Data} ->
-            update_config(),
-            {200, #{code => 0, data => format_api_reply(emqx_resource_api:format_data(Data))}};
+            update_config_and_reply(Name, BridgeType, Config, Data);
         {error, already_created} ->
             {400, #{code => 102, message => <<"bridge already created: ", Name/binary>>}};
         {error, Reason0} ->
@@ -91,10 +92,9 @@ update_bridge(#{name := Name}, Params) ->
     BridgeType = proplists:get_value(<<"type">>, Params),
     case emqx_resource:check_and_update(
             emqx_data_bridge:name_to_resource_id(Name),
-            emqx_data_bridge:resource_type(BridgeType), Config, []) of
+            emqx_data_bridge:resource_type(atom(BridgeType)), maps:from_list(Config), []) of
         {ok, Data} ->
-            update_config(),
-            {200, #{code => 0, data => format_api_reply(emqx_resource_api:format_data(Data))}};
+            update_config_and_reply(Name, BridgeType, Config, Data);
         {error, not_found} ->
             {400, #{code => 102, message => <<"bridge not_found: ", Name/binary>>}};
         {error, Reason0} ->
@@ -105,9 +105,7 @@ update_bridge(#{name := Name}, Params) ->
 
 delete_bridge(#{name := Name}, _Params) ->
     case emqx_resource:remove(emqx_data_bridge:name_to_resource_id(Name)) of
-        ok ->
-            update_config(),
-            {200, #{code => 0, data => #{}}};
+        ok -> delete_config_and_reply(Name);
         {error, Reason} ->
             {500, #{code => 102, message => emqx_resource_api:stringnify(Reason)}}
     end.
@@ -117,12 +115,28 @@ format_api_reply(#{resource_type := Type, id := Id, config := Conf, status := St
       name => emqx_data_bridge:resource_id_to_name(Id),
       config => Conf, status => Status}.
 
-format_conf(#{resource_type := Type, id := Id, config := Conf}) ->
-    #{type => Type, name => emqx_data_bridge:resource_id_to_name(Id),
-      config => Conf}.
+% format_conf(#{resource_type := Type, id := Id, config := Conf}) ->
+%     #{type => Type, name => emqx_data_bridge:resource_id_to_name(Id),
+%       config => Conf}.
 
-get_all_configs() ->
-    [format_conf(Data) || Data <- emqx_data_bridge:list_bridges()].
+% get_all_configs() ->
+%     [format_conf(Data) || Data <- emqx_data_bridge:list_bridges()].
 
-update_config() ->
-    emqx_config_handler:update_config(emqx_data_bridge_config_handler, get_all_configs()).
+update_config_and_reply(Name, BridgeType, Config, Data) ->
+    case emqx_data_bridge:update_config({update, ?BRIDGE(Name, BridgeType, Config)}) of
+        ok ->
+            {200, #{code => 0, data => format_api_reply(
+                        emqx_resource_api:format_data(Data))}};
+        {error, Reason} ->
+            {500, #{code => 102, message => emqx_resource_api:stringnify(Reason)}}
+    end.
+
+delete_config_and_reply(Name) ->
+    case emqx_data_bridge:update_config({delete, Name}) of
+        ok -> {200, #{code => 0, data => #{}}};
+        {error, Reason} ->
+            {500, #{code => 102, message => emqx_resource_api:stringnify(Reason)}}
+    end.
+
+atom(B) when is_binary(B) ->
+    list_to_existing_atom(binary_to_list(B)).
diff --git a/apps/emqx_data_bridge/src/emqx_data_bridge_app.erl b/apps/emqx_data_bridge/src/emqx_data_bridge_app.erl
index 90ab8056f..967791643 100644
--- a/apps/emqx_data_bridge/src/emqx_data_bridge_app.erl
+++ b/apps/emqx_data_bridge/src/emqx_data_bridge_app.erl
@@ -17,14 +17,26 @@
 
 -behaviour(application).
 
--export([start/2, stop/1]).
+-behaviour(emqx_config_handler).
+
+-export([start/2, stop/1, handle_update_config/2]).
 
 start(_StartType, _StartArgs) ->
     {ok, Sup} = emqx_data_bridge_sup:start_link(),
     ok = emqx_data_bridge:load_bridges(),
+    emqx_config_handler:add_handler(emqx_data_bridge:config_key_path(), ?MODULE),
     {ok, Sup}.
 
 stop(_State) ->
     ok.
 
 %% internal functions
+handle_update_config({update, Bridge = #{<<"name">> := Name}}, OldConf) ->
+    [Bridge | remove_bridge(Name, OldConf)];
+handle_update_config({delete, Name}, OldConf) ->
+    remove_bridge(Name, OldConf).
+
+remove_bridge(_Name, undefined) ->
+    [];
+remove_bridge(Name, OldConf) ->
+    [B || B = #{<<"name">> := Name0} <- OldConf, Name0 =/= Name].
diff --git a/apps/emqx_data_bridge/src/emqx_data_bridge_schema.erl b/apps/emqx_data_bridge/src/emqx_data_bridge_schema.erl
deleted file mode 100644
index 2c974029c..000000000
--- a/apps/emqx_data_bridge/src/emqx_data_bridge_schema.erl
+++ /dev/null
@@ -1,23 +0,0 @@
--module(emqx_data_bridge_schema).
-
--export([structs/0, fields/1]).
-
--define(BRIDGE_FIELDS(T),
-    [{name, hoconsc:t(typerefl:binary())},
-     {type, hoconsc:t(typerefl:atom(T))},
-     {config, hoconsc:t(hoconsc:ref(list_to_atom("emqx_connector_"++atom_to_list(T)), ""))}]).
-
--define(TYPES, [mysql, pgsql, mongo, redis, ldap]).
--define(BRIDGES, [hoconsc:ref(T) || T <- ?TYPES]).
-
-structs() -> [emqx_data_bridge].
-
-fields(emqx_data_bridge) ->
-    [{bridges, #{type => hoconsc:array(hoconsc:union(?BRIDGES)),
-                 default => []}}];
-
-fields(mysql) -> ?BRIDGE_FIELDS(mysql);
-fields(pgsql) -> ?BRIDGE_FIELDS(pgsql);
-fields(mongo) -> ?BRIDGE_FIELDS(mongo);
-fields(redis) -> ?BRIDGE_FIELDS(redis);
-fields(ldap) -> ?BRIDGE_FIELDS(ldap).
diff --git a/apps/emqx_data_bridge/src/emqx_data_bridge_sup.erl b/apps/emqx_data_bridge/src/emqx_data_bridge_sup.erl
index 3ac1af7b2..a699a72a0 100644
--- a/apps/emqx_data_bridge/src/emqx_data_bridge_sup.erl
+++ b/apps/emqx_data_bridge/src/emqx_data_bridge_sup.erl
@@ -35,13 +35,8 @@ init([]) ->
           start => {emqx_data_bridge_monitor, start_link, []},
           restart => permanent,
           type => worker,
-          modules => [emqx_data_bridge_monitor]},
-        emqx_config_handler:child_spec(emqx_data_bridge_config_handler, emqx_config_handler,
-            config_key_path())
+          modules => [emqx_data_bridge_monitor]}
     ],
     {ok, {SupFlags, ChildSpecs}}.
 
 %% internal functions
-
-config_key_path() ->
-    [emqx_data_bridge, bridges].
diff --git a/apps/emqx_management/src/emqx_mgmt_http.erl b/apps/emqx_management/src/emqx_mgmt_http.erl
index b902e486e..4b927a982 100644
--- a/apps/emqx_management/src/emqx_mgmt_http.erl
+++ b/apps/emqx_management/src/emqx_mgmt_http.erl
@@ -84,7 +84,7 @@ listener_name(Proto) ->
     list_to_atom(atom_to_list(Proto) ++ ":management").
 
 http_handlers() ->
-    Apps = [ App || {App, _, _} <- application:which_applications(),
+    Apps = [ App || {App, _, _} <- application:loaded_applications(),
                     case re:run(atom_to_list(App), "^emqx") of
                         {match,[{0,4}]} -> true;
                         _ -> false
diff --git a/apps/emqx_resource/examples/demo.md b/apps/emqx_resource/examples/demo.md
index 76b9dee19..0a15be7c5 100644
--- a/apps/emqx_resource/examples/demo.md
+++ b/apps/emqx_resource/examples/demo.md
@@ -77,7 +77,7 @@ emqx_resource:query(ResourceID, {sql, SQL}).
          <<"keyfile">> => [],<<"password">> => "public",
          <<"pool_size">> => 1,
          <<"server">> => {{127,0,0,1},3306},
-         <<"ssl">> => false,<<"user">> => "root",
+         <<"ssl">> => false,<<"username">> => "root",
          <<"verify">> => false},
    id => <<"bridge:mysql-def">>,mod => emqx_connector_mysql,
    state => #{poolname => 'bridge:mysql-def'},
@@ -107,7 +107,7 @@ BridgeMySQL='{
     "status": "started",
     "config": {
       "verify": false,
-      "user": "root",
+      "username": "root",
       "ssl": false,
       "server": "127.0.0.1:3306",
       "pool_size": 1,
@@ -135,7 +135,7 @@ BridgeMySQL='{
     "status": "started",
     "config": {
       "verify": false,
-      "user": "root",
+      "username": "root",
       "ssl": false,
       "server": "127.0.0.1:3306",
       "pool_size": 2,
diff --git a/apps/emqx_telemetry/src/emqx_telemetry.erl b/apps/emqx_telemetry/src/emqx_telemetry.erl
index ea4017dc9..dba22e85b 100644
--- a/apps/emqx_telemetry/src/emqx_telemetry.erl
+++ b/apps/emqx_telemetry/src/emqx_telemetry.erl
@@ -16,6 +16,10 @@
 
 -module(emqx_telemetry).
 
+-include_lib("typerefl/include/types.hrl").
+
+-behaviour(hocon_schema).
+
 -behaviour(gen_server).
 
 -include_lib("emqx/include/emqx.hrl").
@@ -36,6 +40,9 @@
         , stop/0
         ]).
 
+-export([ structs/0
+        , fields/1]).
+
 %% gen_server callbacks
 -export([ init/1
         , handle_call/3
@@ -90,6 +97,12 @@
 
 -define(TELEMETRY, emqx_telemetry).
 
+%%--------------------------------------------------------------------
+structs() -> ["emqx_telemetry"].
+
+fields("emqx_telemetry") ->
+    [{enabled, emqx_schema:t(boolean(), undefined, false)}].
+
 %%--------------------------------------------------------------------
 %% Mnesia bootstrap
 %%--------------------------------------------------------------------
diff --git a/apps/emqx_telemetry/src/emqx_telemetry_app.erl b/apps/emqx_telemetry/src/emqx_telemetry_app.erl
index 8a5b34627..89a30393b 100644
--- a/apps/emqx_telemetry/src/emqx_telemetry_app.erl
+++ b/apps/emqx_telemetry/src/emqx_telemetry_app.erl
@@ -25,13 +25,6 @@
         ]).
 
 start(_Type, _Args) ->
-    %% TODO
-    %% After the relevant code for building hocon configuration will be deleted
-    %% Get the configuration using emqx_config:get
-    ConfFile = filename:join([emqx:get_env(plugins_etc_dir), ?APP]) ++ ".conf",
-    {ok, RawConfig} = hocon:load(ConfFile),
-    Config = hocon_schema:check_plain(emqx_telemetry_schema, RawConfig, #{atom_key => true}),
-    emqx_config_handler:update_config(emqx_config_handler, Config),
     Enabled = emqx_config:get([?APP, enabled], true),
     emqx_telemetry_sup:start_link([{enabled, Enabled}]).
 
diff --git a/apps/emqx_telemetry/src/emqx_telemetry_schema.erl b/apps/emqx_telemetry/src/emqx_telemetry_schema.erl
deleted file mode 100644
index 1a60ac946..000000000
--- a/apps/emqx_telemetry/src/emqx_telemetry_schema.erl
+++ /dev/null
@@ -1,13 +0,0 @@
--module(emqx_telemetry_schema).
-
--include_lib("typerefl/include/types.hrl").
-
--behaviour(hocon_schema).
-
--export([ structs/0
-        , fields/1]).
-
-structs() -> ["emqx_telemetry"].
-
-fields("emqx_telemetry") ->
-    [{enabled, emqx_schema:t(boolean(), undefined, false)}].
diff --git a/rebar.config b/rebar.config
index d2288c5ce..915931709 100644
--- a/rebar.config
+++ b/rebar.config
@@ -53,7 +53,7 @@
     , {observer_cli, "1.6.1"} % NOTE: depends on recon 2.5.1
     , {getopt, "1.0.1"}
     , {snabbkaffe, {git, "https://github.com/kafka4beam/snabbkaffe.git", {tag, "0.13.0"}}}
-    , {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.7.0"}}}
+    , {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.9.0"}}}
     , {emqx_http_lib, {git, "https://github.com/emqx/emqx_http_lib.git", {tag, "0.2.1"}}}
     ]}.
 
diff --git a/rebar.config.erl b/rebar.config.erl
index 56987485e..8ce3aa217 100644
--- a/rebar.config.erl
+++ b/rebar.config.erl
@@ -104,7 +104,8 @@ test_plugins() ->
 
 test_deps() ->
     [ {bbmustache, "1.10.0"}
-    , {emqx_ct_helpers, {git, "https://github.com/emqx/emqx-ct-helpers", {tag, "2.0.0"}}}
+    %, {emqx_ct_helpers, {git, "https://github.com/emqx/emqx-ct-helpers", {tag, "2.0.0"}}}
+    , {emqx_ct_helpers, {git, "https://github.com/emqx/emqx-ct-helpers", {branch, "hocon"}}}
     , meck
     ].