feat(exhook): support customize hook_priority

apps/emqx_exhook/etc/emqx_exhook.conf

@@ -24,6 +24,17 @@
 ## Value: false | Duration
 #exhook.auto_reconnect = 60s
 
+## The exhook execution priority on the Chain of the emqx hooks.
+##
+## Modify the field to fix the exhook execute order before/after other plugins/modules.
+## By default, most hooks registered by plugins or modules have a priority of 0.
+##
+## With the same priority of 0, the execute order depends on hookpoints mount order.
+## Scilicet is the loaded order of plugins/ modules.
+##
+## Default: 0
+## Value: Integer
+#exhook.hook_priority = 0
 
 ##--------------------------------------------------------------------
 ## The Hook callback servers

apps/emqx_exhook/include/emqx_exhook.hrl

@@ -41,4 +41,6 @@
       , {'message.dropped',     {emqx_exhook_handler, on_message_dropped,      []}}
       ]).
 
+-define(DEFAULT_HOOK_PRIORITY, 0).
+
 -endif.

apps/emqx_exhook/priv/emqx_exhook.schema

@@ -15,6 +15,11 @@
   {datatype, string}
 ]}.
 
+{mapping, "exhook.hook_priority", "emqx_exhook.hook_priority", [
+  {default, 0},
+  {datatype, integer}
+]}.
+
 {translation, "emqx_exhook.auto_reconnect", fun(Conf) ->
   case cuttlefish:conf_get("exhook.auto_reconnect", Conf) of
       "false" -> false;

apps/emqx_exhook/src/emqx_exhook_mngr.erl

@@ -23,7 +23,7 @@
 -include_lib("emqx/include/logger.hrl").
 
 %% APIs
--export([start_link/3]).
+-export([start_link/4]).
 
 %% Mgmt API
 -export([ enable/2
@@ -59,9 +59,14 @@
           %% Request options
           request_options :: grpc_client:options(),
           %% Timer references
-          trefs :: map()
+          trefs :: map(),
+          %% Hooks execute options
+          hooks_options :: hooks_options()
          }).
 
+-export_type([ server_options/0
+             , hooks_options/0]).
+
 -type servers() :: [{Name :: atom(), server_options()}].
 
 -type server_options() :: [ {scheme, http | https}
@@ -69,6 +74,8 @@
                           | {port, inet:port_number()}
                           ].
 
+-type hooks_options() :: #{hook_priority => integer()}.
+
 -define(DEFAULT_TIMEOUT, 60000).
 
 -define(CNTER, emqx_exhook_counter).
@@ -77,12 +84,12 @@
 %% APIs
 %%--------------------------------------------------------------------
 
--spec start_link(servers(), false | non_neg_integer(), grpc_client:options())
+-spec start_link(servers(), false | non_neg_integer(), grpc_client:options(), hooks_options())
     ->ignore
      | {ok, pid()}
      | {error, any()}.
-start_link(Servers, AutoReconnect, ReqOpts) ->
+start_link(Servers, AutoReconnect, ReqOpts, HooksOpts) ->
-    gen_server:start_link(?MODULE, [Servers, AutoReconnect, ReqOpts], []).
+    gen_server:start_link(?MODULE, [Servers, AutoReconnect, ReqOpts, HooksOpts], []).
 
 -spec enable(pid(), atom()|string()) -> ok | {error, term()}.
 enable(Pid, Name) ->
@@ -102,7 +109,7 @@ call(Pid, Req) ->
 %% gen_server callbacks
 %%--------------------------------------------------------------------
 
-init([Servers, AutoReconnect, ReqOpts0]) ->
+init([Servers, AutoReconnect, ReqOpts0, HooksOpts]) ->
     process_flag(trap_exit, true),
     %% XXX: Due to the ExHook Module in the enterprise,
     %% this process may start multiple times and they will share this table
@@ -120,32 +127,33 @@ init([Servers, AutoReconnect, ReqOpts0]) ->
 
     %% Load the hook servers
     ReqOpts = maps:without([request_failed_action], ReqOpts0),
-    {Waiting, Running} = load_all_servers(Servers, ReqOpts),
+    {Waiting, Running} = load_all_servers(Servers, ReqOpts, HooksOpts),
     {ok, ensure_reload_timer(
            #state{waiting = Waiting,
                   running = Running,
                   stopped = #{},
                   request_options = ReqOpts,
                   auto_reconnect = AutoReconnect,
-                  trefs = #{}
+                  trefs = #{},
+                  hooks_options = HooksOpts
                  }
           )}.
 
 %% @private
-load_all_servers(Servers, ReqOpts) ->
+load_all_servers(Servers, ReqOpts, HooksOpts) ->
-    load_all_servers(Servers, ReqOpts, #{}, #{}).
+    load_all_servers(Servers, ReqOpts, HooksOpts, #{}, #{}).
-load_all_servers([], _Request, Waiting, Running) ->
+load_all_servers([], _Request, _HooksOpts, Waiting, Running) ->
     {Waiting, Running};
-load_all_servers([{Name, Options}|More], ReqOpts, Waiting, Running) ->
+load_all_servers([{Name, Options} | More], ReqOpts, HooksOpts, Waiting, Running) ->
     {NWaiting, NRunning} =
-        case emqx_exhook_server:load(Name, Options, ReqOpts) of
+        case emqx_exhook_server:load(Name, Options, ReqOpts, HooksOpts) of
             {ok, ServerState} ->
                 save(Name, ServerState),
                 {Waiting, Running#{Name => Options}};
             {error, _} ->
                 {Waiting#{Name => Options}, Running}
         end,
-    load_all_servers(More, ReqOpts, NWaiting, NRunning).
+    load_all_servers(More, ReqOpts, HooksOpts, NWaiting, NRunning).
 
 handle_call({load, Name}, _From, State) ->
     {Result, NState} = do_load_server(Name, State),
@@ -214,7 +222,8 @@ do_load_server(Name, State0 = #state{
                                  waiting = Waiting,
                                  running = Running,
                                  stopped = Stopped,
-                                 request_options = ReqOpts}) ->
+                                 request_options = ReqOpts,
+                                 hooks_options = HooksOpts}) ->
     State = clean_reload_timer(Name, State0),
     case maps:get(Name, Running, undefined) of
         undefined ->
@@ -223,7 +232,7 @@ do_load_server(Name, State0 = #state{
                 undefined ->
                     {{error, not_found}, State};
                 Options ->
-                    case emqx_exhook_server:load(Name, Options, ReqOpts) of
+                    case emqx_exhook_server:load(Name, Options, ReqOpts, HooksOpts) of
                         {ok, ServerState} ->
                             save(Name, ServerState),
                             ?LOG(info, "Load exhook callback server "

apps/emqx_exhook/src/emqx_exhook_server.erl

@@ -25,7 +25,7 @@
 -define(PB_CLIENT_MOD, emqx_exhook_v_1_hook_provider_client).
 
 %% Load/Unload
--export([ load/3
+-export([ load/4
         , unload/1
         ]).
 
@@ -81,8 +81,9 @@
 %% Load/Unload APIs
 %%--------------------------------------------------------------------
 
--spec load(atom(), list(), map()) -> {ok, server()} | {error, term()} .
+-spec load(atom(), emqx_exhook_mngr:server_options(), grpc_client:options(), emqx_exhook_mngr:hooks_options())
-load(Name0, Opts0, ReqOpts) ->
+          -> {ok, server()} | {error, term()} .
+load(Name0, Opts0, ReqOpts, HooksOpts) ->
     Name = to_list(Name0),
     {SvrAddr, ClientOpts} = channel_opts(Opts0),
     case emqx_exhook_sup:start_grpc_client_channel(
@@ -97,7 +98,7 @@ load(Name0, Opts0, ReqOpts) ->
                                io_lib:format("exhook.~s.", [Name])),
                     ensure_metrics(Prefix, HookSpecs),
                     %% Ensure hooks
-                    ensure_hooks(HookSpecs),
+                    ensure_hooks(HookSpecs, maps:get(hook_priority, HooksOpts, ?DEFAULT_HOOK_PRIORITY)),
                     {ok, #server{name = Name,
                                  options = ReqOpts,
                                  channel = _ChannPoolPid,
@@ -193,13 +194,13 @@ ensure_metrics(Prefix, HookSpecs) ->
             || Hookpoint <- maps:keys(HookSpecs)],
     lists:foreach(fun emqx_metrics:ensure/1, Keys).
 
-ensure_hooks(HookSpecs) ->
+ensure_hooks(HookSpecs, Priority) ->
     lists:foreach(fun(Hookpoint) ->
         case lists:keyfind(Hookpoint, 1, ?ENABLED_HOOKS) of
             false ->
                 ?LOG(error, "Unknown name ~s to hook, skip it!", [Hookpoint]);
             {Hookpoint, {M, F, A}} ->
-                emqx_hooks:put(Hookpoint, {M, F, A}),
+                emqx_hooks:put(Hookpoint, {M, F, A}, Priority),
                 ets:update_counter(?CNTER, Hookpoint, {2, 1}, {Hookpoint, 0})
         end
     end, maps:keys(HookSpecs)).

apps/emqx_exhook/src/emqx_exhook_sup.erl

@@ -18,6 +18,8 @@
 
 -behaviour(supervisor).
 
+-include("emqx_exhook.hrl").
+
 -export([ start_link/0
         , init/1
         ]).
@@ -43,7 +45,7 @@ start_link() ->
 
 init([]) ->
     Mngr = ?CHILD(emqx_exhook_mngr, worker,
-                  [servers(), auto_reconnect(), request_options()]),
+                  [servers(), auto_reconnect(), request_options(), hooks_options()]),
     {ok, {{one_for_one, 10, 100}, [Mngr]}}.
 
 servers() ->
@@ -57,6 +59,10 @@ request_options() ->
       request_failed_action => env(request_failed_action, deny)
      }.
 
+hooks_options() ->
+    #{hook_priority => env(hook_priority, ?DEFAULT_HOOK_PRIORITY)
+     }.
+
 env(Key, Def) ->
     application:get_env(emqx_exhook, Key, Def).