emqx4.3/apps/emqx_modules/src/emqx_modules_app.erl

%%--------------------------------------------------------------------
%% Copyright (c) 2021-2022 EMQ Technologies Co., Ltd. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%--------------------------------------------------------------------

-module(emqx_modules_app).

-behaviour(application).

-export([
    start/2,
    stop/1
]).

start(_Type, _Args) ->
    {ok, Sup} = emqx_modules_sup:start_link(),
    maybe_enable_modules(),
    {ok, Sup}.

stop(_State) ->
    maybe_disable_modules(),
    ok.

maybe_enable_modules() ->
    DelayedEnabled = emqx_conf:get([delayed, enable], true),
    RewriteEnabled = length(emqx_conf:get([rewrite], [])) > 0,
    RetainerEnabled = emqx_conf:get([retainer, enable], false),
    AutoSubscribeEnabled = length(emqx_conf:get([auto_subscribe, topics], [])) > 0,
    application:set_env(
        emqx_modules,
        advanced_mqtt_features_in_use,
        #{
            delayed => DelayedEnabled,
            topic_rewrite => RewriteEnabled,
            retained => RetainerEnabled,
            auto_subscribe => AutoSubscribeEnabled
        }
    ),
    DelayedEnabled andalso emqx_delayed:enable(),
    emqx_conf:get([telemetry, enable], true) andalso emqx_telemetry:enable(),
    emqx_conf:get([observer_cli, enable], true) andalso emqx_observer_cli:enable(),
    emqx_conf_cli:load(),
    ok = emqx_rewrite:enable(),
    emqx_topic_metrics:enable(),
    emqx_modules_conf:load().

maybe_disable_modules() ->
    emqx_conf:get([delayed, enable], true) andalso emqx_delayed:disable(),
    emqx_conf:get([telemetry, enable], true) andalso emqx_telemetry:disable(),
    emqx_conf:get([observer_cli, enable], true) andalso emqx_observer_cli:disable(),
    emqx_rewrite:disable(),
    emqx_conf_cli:unload(),
    emqx_topic_metrics:disable(),
    emqx_modules_conf:unload().