From 3d1f0c756cd8a63412858c2b631b7879fba5ccc1 Mon Sep 17 00:00:00 2001
From: JimMoen <LnJimMoen@outlook.com>
Date: Mon, 29 Jul 2024 15:29:01 +0800
Subject: [PATCH 1/2] feat: call plugin's app module `on_config_changed/2`
 callback

assume the module: `[PluginName]_app`
---
 apps/emqx_plugins/src/emqx_plugins.erl | 30 ++++++++++++++++++++++++--
 changes/ce/feat-13548.en.md            |  6 ++++++
 2 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 changes/ce/feat-13548.en.md

diff --git a/apps/emqx_plugins/src/emqx_plugins.erl b/apps/emqx_plugins/src/emqx_plugins.erl
index 253d1b4ef..56a88d7cb 100644
--- a/apps/emqx_plugins/src/emqx_plugins.erl
+++ b/apps/emqx_plugins/src/emqx_plugins.erl
@@ -356,13 +356,13 @@ get_config_bin(NameVsn) ->
 %% RPC call from Management API or CLI.
 %% The plugin config Json Map was valid by avro schema
 %% Or: if no and plugin config ALWAYS be valid before calling this function.
-put_config(NameVsn, ConfigJsonMap, AvroValue) when not is_binary(NameVsn) ->
+put_config(NameVsn, ConfigJsonMap, AvroValue) when (not is_binary(NameVsn)) ->
     put_config(bin(NameVsn), ConfigJsonMap, AvroValue);
 put_config(NameVsn, ConfigJsonMap, _AvroValue) ->
     HoconBin = hocon_pp:do(ConfigJsonMap, #{}),
     ok = backup_and_write_hocon_bin(NameVsn, HoconBin),
-    %% TODO: callback in plugin's on_config_changed (config update by mgmt API)
     %% TODO: callback in plugin's on_config_upgraded (config vsn upgrade v1 -> v2)
+    ok = maybe_call_on_config_changed(NameVsn, ConfigJsonMap),
     ok = persistent_term:put(?PLUGIN_PERSIS_CONFIG_KEY(NameVsn), ConfigJsonMap),
     ok.
 
@@ -373,6 +373,32 @@ restart(NameVsn) ->
         {error, Reason} -> {error, Reason}
     end.
 
+%% @doc Call plugin's callback on_config_changed/2
+maybe_call_on_config_changed(NameVsn, NewConf) ->
+    FuncName = on_config_changed,
+    maybe
+        {ok, PluginAppModule} ?= app_module_name(NameVsn),
+        true ?= erlang:function_exported(PluginAppModule, FuncName, 2),
+        {ok, OldConf} = get_config(NameVsn),
+        _ = erlang:apply(PluginAppModule, FuncName, [OldConf, NewConf])
+    else
+        {error, Reason} ->
+            ?SLOG(info, #{msg => "failed_to_call_on_config_changed", reason => Reason});
+        false ->
+            ?SLOG(info, #{msg => "on_config_changed_callback_not_exported"});
+        _ ->
+            ok
+    end.
+
+app_module_name(NameVsn) ->
+    case read_plugin_info(NameVsn, #{}) of
+        {ok, #{<<"name">> := Name} = _PluginInfo} ->
+            emqx_utils:safe_to_existing_atom(<<Name/binary, "_app">>);
+        {error, Reason} ->
+            ?SLOG(error, Reason#{msg => "failed_to_read_plugin_info"}),
+            {error, Reason}
+    end.
+
 %% @doc List all installed plugins.
 %% Including the ones that are installed, but not enabled in config.
 -spec list() -> [plugin_info()].
diff --git a/changes/ce/feat-13548.en.md b/changes/ce/feat-13548.en.md
new file mode 100644
index 000000000..75b56cd43
--- /dev/null
+++ b/changes/ce/feat-13548.en.md
@@ -0,0 +1,6 @@
+Optionally calls the `on_config_changed/2` callback function when the plugin configuration is updated via the REST API.
+
+This callback function is assumed to be exported by the `<PluginName>_app` module.
+i.e:
+Plugin NameVsn: `my_plugin-1.0.0`
+This callback function is assumed to be `my_plugin_app:on_config_changed/2`

From e6bfc14cc9f8f7c792dc55c96fe81e38f9acb237 Mon Sep 17 00:00:00 2001
From: JimMoen <LnJimMoen@outlook.com>
Date: Wed, 31 Jul 2024 09:26:44 +0800
Subject: [PATCH 2/2] fix: try-catch optional `on_config_changed/2` plugin app
 callback

---
 apps/emqx_plugins/src/emqx_plugins.erl | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/apps/emqx_plugins/src/emqx_plugins.erl b/apps/emqx_plugins/src/emqx_plugins.erl
index 56a88d7cb..94c6aa4e1 100644
--- a/apps/emqx_plugins/src/emqx_plugins.erl
+++ b/apps/emqx_plugins/src/emqx_plugins.erl
@@ -380,7 +380,18 @@ maybe_call_on_config_changed(NameVsn, NewConf) ->
         {ok, PluginAppModule} ?= app_module_name(NameVsn),
         true ?= erlang:function_exported(PluginAppModule, FuncName, 2),
         {ok, OldConf} = get_config(NameVsn),
-        _ = erlang:apply(PluginAppModule, FuncName, [OldConf, NewConf])
+        try erlang:apply(PluginAppModule, FuncName, [OldConf, NewConf]) of
+            _ -> ok
+        catch
+            Class:CatchReason:Stacktrace ->
+                ?SLOG(error, #{
+                    msg => "failed_to_call_on_config_changed",
+                    exception => Class,
+                    reason => CatchReason,
+                    stacktrace => Stacktrace
+                }),
+                ok
+        end
     else
         {error, Reason} ->
             ?SLOG(info, #{msg => "failed_to_call_on_config_changed", reason => Reason});