fix(gcp_pubsub): ensure jwt token is deleted after worker stops and always ensure refresh timer (v4.4)

https://emqx.atlassian.net/browse/EMQX-8652

Since the rule resource testing mechanism creates a new resource to
test the configuration, a new JWT associated with an unique temporary
resource was being created and left in the JWT table, leaking it.

Also, a wrong case clause when setting the new refresh timer for the
JWT worker was preventing it from refreshing from the 2nd refresh
onward.

apps/emqx_rule_engine/src/emqx_rule_engine_jwt.erl

@@ -22,6 +22,7 @@
 %% API
 -export([ lookup_jwt/1
         , lookup_jwt/2
+        , delete_jwt/2
         ]).
 
 -type jwt() :: binary().
@@ -43,3 +44,13 @@ lookup_jwt(TId, ResourceId) ->
         error:badarg ->
             {error, not_found}
     end.
+
+-spec delete_jwt(ets:table(), resource_id()) -> ok.
+delete_jwt(TId, ResourceId) ->
+    try
+        ets:delete(TId, {ResourceId, jwt}),
+        ok
+    catch
+        error:badarg ->
+            ok
+    end.

apps/emqx_rule_engine/src/emqx_rule_engine_jwt_sup.erl

@@ -72,7 +72,7 @@ jwt_worker_child_spec(Id, Config) ->
      , restart => transient
      , type => worker
      , significant => false
-     , shutdown => brutal_kill
+     , shutdown => 5_000
      , modules => [emqx_rule_engine_jwt_worker]
      }.
 

apps/emqx_rule_engine/src/emqx_rule_engine_jwt_worker.erl

@@ -31,8 +31,11 @@
         , handle_info/2
         , format_status/1
         , format_status/2
+        , terminate/2
         ]).
 
+-export([force_refresh/1]).
+
 -include_lib("jose/include/jose_jwk.hrl").
 -include_lib("emqx_rule_engine/include/rule_engine.hrl").
 -include_lib("emqx_rule_engine/include/rule_actions.hrl").
@@ -49,7 +52,7 @@
                    , alg := binary()
                    }.
 -type jwt() :: binary().
--type state() :: #{ refresh_timer := undefined | timer:tref()
+-type state() :: #{ refresh_timer := undefined | timer:tref() | reference()
                   , resource_id := resource_id()
                   , expiration := timer:time()
                   , table := ets:table()
@@ -88,6 +91,11 @@ ensure_jwt(Worker) ->
     gen_server:cast(Worker, {ensure_jwt, Ref}),
     Ref.
 
+-spec force_refresh(pid()) -> ok.
+force_refresh(Worker) ->
+    _ = erlang:send(Worker, {timeout, force_refresh, ?refresh_jwt}),
+    ok.
+
 %%-----------------------------------------------------------------------------------------
 %% gen_server API
 %%-----------------------------------------------------------------------------------------
@@ -95,6 +103,7 @@ ensure_jwt(Worker) ->
 -spec init(config()) -> {ok, state(), {continue, {make_key, binary()}}}
                         | {stop, {error, term()}}.
 init(#{private_key := PrivateKeyPEM} = Config) ->
+    process_flag(trap_exit, true),
     State0 = maps:without([private_key], Config),
     State = State0#{ jwk => undefined
                    , jwt => undefined
@@ -139,7 +148,7 @@ handle_cast({ensure_jwt, From}, State0 = #{jwt := JWT}) ->
 handle_cast(_Req, State) ->
     {noreply, State}.
 
-handle_info({timeout, TRef, ?refresh_jwt}, State0 = #{refresh_timer := TRef}) ->
+handle_info({timeout, _TRef, ?refresh_jwt}, State0) ->
     State = generate_and_store_jwt(State0),
     {noreply, State};
 handle_info(_Msg, State) ->
@@ -152,6 +161,11 @@ format_status(_Opt, [_PDict, State0]) ->
     State = censor_secrets(State0),
     [{data, [{"State", State}]}].
 
+terminate(_Reason, State) ->
+    #{resource_id := ResourceId, table := TId} = State,
+    emqx_rule_engine_jwt:delete_jwt(TId, ResourceId),
+    ok.
+
 %%-----------------------------------------------------------------------------------------
 %% Helper fns
 %%-----------------------------------------------------------------------------------------
@@ -195,14 +209,13 @@ store_jwt(#{resource_id := ResourceId, table := TId}, JWT) ->
     ok.
 
 -spec ensure_timer(state()) -> state().
-ensure_timer(State = #{ refresh_timer := undefined
+ensure_timer(State = #{ refresh_timer := OldTimer
                       , expiration := ExpirationMS0
                       }) ->
-    ExpirationMS = max(5_000, ExpirationMS0 - 5_000),
+    ok = cancel_timer(OldTimer),
+    ExpirationMS = max(5_000, ExpirationMS0 - 60_000),
     TRef = erlang:start_timer(ExpirationMS, self(), ?refresh_jwt),
-    State#{refresh_timer => TRef};
-ensure_timer(State) ->
-    State.
+    State#{refresh_timer => TRef}.
 
 -spec censor_secrets(state()) -> map().
 censor_secrets(State) ->
@@ -214,3 +227,10 @@ censor_secrets(State) ->
              Value
      end,
      State).
+
+-spec cancel_timer(undefined | timer:tref() | reference()) -> ok.
+cancel_timer(undefined) ->
+    ok;
+cancel_timer(TRef) ->
+    _ = erlang:cancel_timer(TRef),
+    ok.

apps/emqx_rule_engine/test/emqx_rule_engine_jwt_worker_SUITE.erl

@@ -140,12 +140,22 @@ t_refresh(_Config) ->
          {ok, SecondJWT} = emqx_rule_engine_jwt:lookup_jwt(Table, ResourceId),
          ?assertNot(is_expired(SecondJWT)),
          ?assert(is_expired(FirstJWT)),
-         {FirstJWT, SecondJWT}
+         %% check yet another refresh to ensure the timer was properly
+         %% reset.
+         ?block_until(#{?snk_kind := rule_engine_jwt_worker_refresh,
+                        jwt := JWT1} when JWT1 =/= SecondJWT
+                                          andalso JWT1 =/= FirstJWT, 15_000),
+         {ok, ThirdJWT} = emqx_rule_engine_jwt:lookup_jwt(Table, ResourceId),
+         ?assertNot(is_expired(ThirdJWT)),
+         ?assert(is_expired(SecondJWT)),
+         {FirstJWT, SecondJWT, ThirdJWT}
        end,
-       fun({FirstJWT, SecondJWT}, Trace) ->
-         ?assertMatch([_, _ | _],
+       fun({FirstJWT, SecondJWT, ThirdJWT}, Trace) ->
+         ?assertMatch([_, _, _ | _],
                       ?of_kind(rule_engine_jwt_worker_token_stored, Trace)),
          ?assertNotEqual(FirstJWT, SecondJWT),
+         ?assertNotEqual(SecondJWT, ThirdJWT),
+         ?assertNotEqual(FirstJWT, ThirdJWT),
          ok
        end),
     ok.
@@ -225,7 +235,7 @@ t_lookup_badarg(_Config) ->
 
 t_start_supervised_worker(_Config) ->
     {ok, _} = emqx_rule_engine_jwt_sup:start_link(),
-    Config = #{resource_id := ResourceId} = generate_config(),
+    Config = #{resource_id := ResourceId, table := TId} = generate_config(),
     {ok, Pid} = emqx_rule_engine_jwt_sup:ensure_worker_present(ResourceId, Config),
     Ref = emqx_rule_engine_jwt_worker:ensure_jwt(Pid),
     receive
@@ -237,6 +247,7 @@ t_start_supervised_worker(_Config) ->
     end,
     MRef = monitor(process, Pid),
     ?assert(is_process_alive(Pid)),
+    ?assertMatch({ok, _}, emqx_rule_engine_jwt:lookup_jwt(TId, ResourceId)),
     ok = emqx_rule_engine_jwt_sup:ensure_worker_deleted(ResourceId),
     receive
         {'DOWN', MRef, process, Pid, _} ->
@@ -245,4 +256,7 @@ t_start_supervised_worker(_Config) ->
         1_000 ->
             ct:fail("timeout")
     end,
+    %% ensure it cleans up its own tokens to avoid leakage when
+    %% probing/testing rule resources.
+    ?assertEqual({error, not_found}, emqx_rule_engine_jwt:lookup_jwt(TId, ResourceId)),
     ok.