Revert "fix(machine boot): serialize start/stop apps"

This reverts commit 38586a4c5ee148a88e0cae6b3fa805a3e75eb84e.

apps/emqx_machine/src/emqx_machine_app_booter.erl

@@ -1,129 +0,0 @@
-%%--------------------------------------------------------------------
-%% Copyright (c) 2024 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_machine_app_booter).
-
-%% @doc This process serves as a serialization point for starting and stopping
-%% applications as part of the boot process or when joining a new cluster.  One motivation
-%% for this is that a join request might start while the node is still starting its list
-%% of applications (e.g. when booting the first time).
-
--include_lib("emqx/include/logger.hrl").
--include_lib("snabbkaffe/include/snabbkaffe.hrl").
-
-%% API
--export([
-    start_link/0,
-
-    start_apps/0,
-    stop_apps/0
-]).
-
-%% `gen_server' API
--export([
-    init/1,
-    handle_call/3,
-    handle_cast/2,
-    handle_info/2
-]).
-
-%%------------------------------------------------------------------------------
-%% Type declarations
-%%------------------------------------------------------------------------------
-
-%% calls/casts/infos
--record(start_apps, {}).
--record(stop_apps, {}).
-
-%%------------------------------------------------------------------------------
-%% API
-%%------------------------------------------------------------------------------
-
-start_link() ->
-    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
-
-start_apps() ->
-    gen_server:call(?MODULE, #start_apps{}, infinity).
-
-stop_apps() ->
-    gen_server:call(?MODULE, #stop_apps{}, infinity).
-
-%%------------------------------------------------------------------------------
-%% `gen_server' API
-%%------------------------------------------------------------------------------
-
-init(_Opts) ->
-    %% Ensure that the stop callback is set, so that join requests concurrent to the
-    %% startup are serialized here.
-    %% It would still be problematic if a join request arrives before this process is
-    %% started, though.
-    ekka:callback(stop, fun emqx_machine_boot:stop_apps/0),
-    State = #{},
-    {ok, State}.
-
-handle_call(#start_apps{}, _From, State) ->
-    handle_start_apps(),
-    {reply, ok, State};
-handle_call(#stop_apps{}, _From, State) ->
-    handle_stop_apps(),
-    {reply, ok, State};
-handle_call(_Call, _From, State) ->
-    {reply, ignored, State}.
-
-handle_cast(_Cast, State) ->
-    {noreply, State}.
-
-handle_info(_Info, State) ->
-    {noreply, State}.
-
-%%------------------------------------------------------------------------------
-%% Internal fns
-%%------------------------------------------------------------------------------
-
-handle_start_apps() ->
-    ?SLOG(notice, #{msg => "(re)starting_emqx_apps"}),
-    lists:foreach(fun start_one_app/1, emqx_machine_boot:sorted_reboot_apps()),
-    ?tp(emqx_machine_boot_apps_started, #{}).
-
-handle_stop_apps() ->
-    ?SLOG(notice, #{msg => "stopping_emqx_apps"}),
-    _ = emqx_alarm_handler:unload(),
-    ok = emqx_conf_app:unset_config_loaded(),
-    ok = emqx_plugins:ensure_stopped(),
-    lists:foreach(fun stop_one_app/1, lists:reverse(emqx_machine_boot:sorted_reboot_apps())).
-
-start_one_app(App) ->
-    ?SLOG(debug, #{msg => "starting_app", app => App}),
-    case application:ensure_all_started(App, emqx_machine_boot:restart_type(App)) of
-        {ok, Apps} ->
-            ?SLOG(debug, #{msg => "started_apps", apps => Apps});
-        {error, Reason} ->
-            ?SLOG(critical, #{msg => "failed_to_start_app", app => App, reason => Reason}),
-            error({failed_to_start_app, App, Reason})
-    end.
-
-stop_one_app(App) ->
-    ?SLOG(debug, #{msg => "stopping_app", app => App}),
-    try
-        _ = application:stop(App)
-    catch
-        C:E ->
-            ?SLOG(error, #{
-                msg => "failed_to_stop_app",
-                app => App,
-                exception => C,
-                reason => E
-            })
-    end.

apps/emqx_machine/src/emqx_machine_boot.erl

@@ -24,7 +24,6 @@
 -export([start_autocluster/0]).
 -export([stop_port_apps/0]).
 -export([read_apps/0]).
--export([restart_type/1]).
 
 -dialyzer({no_match, [basic_reboot_apps/0]}).
 
@@ -65,7 +64,11 @@ start_autocluster() ->
     ok.
 
 stop_apps() ->
-    emqx_machine_app_booter:stop_apps().
+    ?SLOG(notice, #{msg => "stopping_emqx_apps"}),
+    _ = emqx_alarm_handler:unload(),
+    ok = emqx_conf_app:unset_config_loaded(),
+    ok = emqx_plugins:ensure_stopped(),
+    lists:foreach(fun stop_one_app/1, lists:reverse(sorted_reboot_apps())).
 
 %% Those port apps are terminated after the main apps
 %% Don't need to stop when reboot.
@@ -96,7 +99,19 @@ stop_one_app(App) ->
     end.
 
 ensure_apps_started() ->
-    emqx_machine_app_booter:start_apps().
+    ?SLOG(notice, #{msg => "(re)starting_emqx_apps"}),
+    lists:foreach(fun start_one_app/1, sorted_reboot_apps()),
+    ?tp(emqx_machine_boot_apps_started, #{}).
+
+start_one_app(App) ->
+    ?SLOG(debug, #{msg => "starting_app", app => App}),
+    case application:ensure_all_started(App, restart_type(App)) of
+        {ok, Apps} ->
+            ?SLOG(debug, #{msg => "started_apps", apps => Apps});
+        {error, Reason} ->
+            ?SLOG(critical, #{msg => "failed_to_start_app", app => App, reason => Reason}),
+            error({failed_to_start_app, App, Reason})
+    end.
 
 restart_type(App) ->
     PermanentApps =

apps/emqx_machine/src/emqx_machine_sup.erl

@@ -29,18 +29,10 @@ start_link() ->
 
 init([]) ->
     Terminator = child_worker(emqx_machine_terminator, [], transient),
-    ReplicantHealthProbe = child_worker(emqx_machine_replicant_health_probe, [], transient),
-    %% Must start before `post_boot'.
-    Booter = child_worker(emqx_machine_app_booter, [], permanent),
     BootApps = child_worker(emqx_machine_boot, post_boot, [], temporary),
     GlobalGC = child_worker(emqx_global_gc, [], permanent),
-    Children = [
-        Terminator,
-        ReplicantHealthProbe,
-        Booter,
-        BootApps,
-        GlobalGC
-    ],
+    ReplicantHealthProbe = child_worker(emqx_machine_replicant_health_probe, [], transient),
+    Children = [Terminator, ReplicantHealthProbe, BootApps, GlobalGC],
     SupFlags = #{
         strategy => one_for_one,
         intensity => 100,

apps/emqx_machine/test/emqx_machine_SUITE.erl

@@ -56,7 +56,6 @@ end_per_suite(Config) ->
 
 app_specs() ->
     [
-        emqx,
         emqx_conf,
         emqx_prometheus,
         emqx_modules,
@@ -114,15 +113,8 @@ t_shutdown_reboot(Config) ->
         [{machine_reboot_SUITE1, #{role => core, apps => app_specs()}}],
         #{work_dir => emqx_cth_suite:work_dir(?FUNCTION_NAME, Config)}
     ),
-    SortedApps = app_specs(),
     try
         erpc:call(Node, fun() ->
-            %% Since `emqx_cth_*' starts applications without going through
-            %% `emqx_machine', we need to start this manually.
-            {ok, _} = emqx_machine_app_booter:start_link(),
-            ok = meck:new(emqx_machine_boot, [passthrough]),
-            ok = meck:expect(emqx_machine_boot, sorted_reboot_apps, 0, SortedApps),
-
             true = emqx:is_running(node()),
             emqx_machine_boot:stop_apps(),
             false = emqx:is_running(node()),

apps/emqx_plugins/test/emqx_plugins_SUITE.erl

@@ -914,10 +914,6 @@ t_start_node_with_plugin_enabled({init, Config}) ->
         emqx_conf,
         emqx_ctl,
         {emqx_plugins, #{
-            after_start => fun() ->
-                {ok, Pid} = emqx_machine_app_booter:start_link(),
-                unlink(Pid)
-            end,
             config =>
                 #{
                     plugins =>

changes/ce/fix-14113.en.md

@@ -1 +0,0 @@
-Fixed a potential race condition where a node that is still starting could crash if it attempted to join a cluster.