fix(trace): several improvements thanks to comments from @zmstone

apps/emqx/src/emqx_trace/emqx_trace.erl

@@ -88,16 +88,18 @@ unsubscribe(Topic, SubOpts) ->
     ?TRACE("UNSUBSCRIBE", "unsubscribe", #{topic => Topic, sub_opts => SubOpts}).
 
 rendered_action_template(ActionID, RenderResult) ->
-    Msg = io_lib:format("action_template_rendered(~s)", [ActionID]),
+    Msg = lists:flatten(io_lib:format("action_template_rendered(~ts)", [ActionID])),
     TraceResult = ?TRACE("QUERY_RENDER", Msg, RenderResult),
     case logger:get_process_metadata() of
         #{stop_action_after_render := true} ->
             %% We throw an unrecoverable error to stop action before the
             %% resource is called/modified
-            StopMsg = io_lib:format(
-                "action_stopped_after_render(~s): "
-                "Action stopped after template render due to test setting.",
-                [ActionID]
+            StopMsg = lists:flatten(
+                io_lib:format(
+                    "action_stopped_after_render(~ts): "
+                    "Action stopped after template render due to test setting.",
+                    [ActionID]
+                )
             ),
             MsgBin = iolist_to_binary(StopMsg),
             error({unrecoverable_error, MsgBin});

apps/emqx_bridge_http/src/emqx_bridge_http_connector.erl

@@ -371,29 +371,7 @@ on_query(
         }
     ),
     NRequest = formalize_request(Method, BasePath, Request),
-    case NRequest of
-        {Path, Headers} ->
-            emqx_trace:rendered_action_template(
-                InstId,
-                #{
-                    path => Path,
-                    method => Method,
-                    headers => Headers,
-                    timeout => Timeout
-                }
-            );
-        {Path, Headers, Body} ->
-            emqx_trace:rendered_action_template(
-                InstId,
-                #{
-                    path => Path,
-                    method => Method,
-                    headers => Headers,
-                    timeout => Timeout,
-                    body => Body
-                }
-            )
-    end,
+    trace_rendered_action_template(InstId, Method, NRequest, Timeout),
     Worker = resolve_pool_worker(State, KeyOrNum),
     Result0 = ehttpc:request(
         Worker,
@@ -503,6 +481,27 @@ on_query_async(
         }
     ),
     NRequest = formalize_request(Method, BasePath, Request),
+    trace_rendered_action_template(InstId, Method, NRequest, Timeout),
+    MaxAttempts = maps:get(max_attempts, State, 3),
+    Context = #{
+        attempt => 1,
+        max_attempts => MaxAttempts,
+        state => State,
+        key_or_num => KeyOrNum,
+        method => Method,
+        request => NRequest,
+        timeout => Timeout
+    },
+    ok = ehttpc:request_async(
+        Worker,
+        Method,
+        NRequest,
+        Timeout,
+        {fun ?MODULE:reply_delegator/3, [Context, ReplyFunAndArgs]}
+    ),
+    {ok, Worker}.
+
+trace_rendered_action_template(InstId, Method, NRequest, Timeout) ->
     case NRequest of
         {Path, Headers} ->
             emqx_trace:rendered_action_template(
@@ -520,30 +519,12 @@ on_query_async(
                 #{
                     path => Path,
                     method => Method,
-                    headers => Headers,
+                    headers => emqx_utils_redact:redact_headers(Headers),
                     timeout => Timeout,
                     body => Body
                 }
             )
-    end,
-    MaxAttempts = maps:get(max_attempts, State, 3),
-    Context = #{
-        attempt => 1,
-        max_attempts => MaxAttempts,
-        state => State,
-        key_or_num => KeyOrNum,
-        method => Method,
-        request => NRequest,
-        timeout => Timeout
-    },
-    ok = ehttpc:request_async(
-        Worker,
-        Method,
-        NRequest,
-        Timeout,
-        {fun ?MODULE:reply_delegator/3, [Context, ReplyFunAndArgs]}
-    ),
-    {ok, Worker}.
+    end.
 
 resolve_pool_worker(State, undefined) ->
     resolve_pool_worker(State, self());

apps/emqx_rule_engine/rebar.config

@@ -2,7 +2,8 @@
 
 {deps, [
     {emqx, {path, "../emqx"}},
-    {emqx_utils, {path, "../emqx_utils"}}
+    {emqx_utils, {path, "../emqx_utils"}},
+    {emqx_modules, {path, "../emqx_modules"}}
 ]}.
 
 {profiles, [

apps/emqx_rule_engine/src/emqx_rule_api_schema.erl

@@ -108,15 +108,6 @@ fields("rule_test") ->
 fields("rule_apply_test") ->
     [
         rule_input_message_context(),
-        {"environment",
-            sc(
-                typerefl:map(),
-                #{
-                    desc =>
-                        ?DESC("test_rule_environment"),
-                    default => #{}
-                }
-            )},
         {"stop_action_after_template_rendering",
             sc(
                 typerefl:boolean(),

apps/emqx_rule_engine/src/emqx_rule_engine.app.src

@@ -17,7 +17,9 @@
         %% rule_engine should wait for bridge connector start,
         %% it's will check action/connector ref's exist.
         emqx_bridge,
-        emqx_connector
+        emqx_connector,
+        %% Needed to start the tracing functionality
+        emqx_modules
     ]},
     {mod, {emqx_rule_engine_app, []}},
     {env, []},

apps/emqx_rule_engine/src/emqx_rule_runtime.erl

@@ -420,13 +420,13 @@ handle_action(RuleId, ActId, Selected, Envs) ->
     end.
 
 -define(IS_RES_DOWN(R), R == stopped; R == not_connected; R == not_found; R == unhealthy_target).
-do_handle_action(_RuleId, {bridge, BridgeType, BridgeName, ResId} = Action, Selected, _Envs) ->
+do_handle_action(RuleId, {bridge, BridgeType, BridgeName, ResId} = Action, Selected, _Envs) ->
     trace_action_bridge("BRIDGE", Action, "bridge_action", #{}, debug),
-    TraceCtx = do_handle_action_get_trace_context(Action),
-    ReplyTo = {fun ?MODULE:inc_action_metrics/2, [TraceCtx], #{reply_dropped => true}},
+    {TraceCtx, IncCtx} = do_handle_action_get_trace_inc_metrics_context(RuleId, Action),
+    ReplyTo = {fun ?MODULE:inc_action_metrics/2, [IncCtx], #{reply_dropped => true}},
     case
         emqx_bridge:send_message(BridgeType, BridgeName, ResId, Selected, #{
-            reply_to => ReplyTo, trace_ctx => maps:remove(action_id, TraceCtx)
+            reply_to => ReplyTo, trace_ctx => TraceCtx
         })
     of
         {error, Reason} when Reason == bridge_not_found; Reason == bridge_stopped ->
@@ -437,20 +437,20 @@ do_handle_action(_RuleId, {bridge, BridgeType, BridgeName, ResId} = Action, Sele
             Result
     end;
 do_handle_action(
-    _RuleId,
+    RuleId,
     {bridge_v2, BridgeType, BridgeName} = Action,
     Selected,
     _Envs
 ) ->
     trace_action_bridge("BRIDGE", Action, "bridge_action", #{}, debug),
-    TraceCtx = do_handle_action_get_trace_context(Action),
-    ReplyTo = {fun ?MODULE:inc_action_metrics/2, [TraceCtx], #{reply_dropped => true}},
+    {TraceCtx, IncCtx} = do_handle_action_get_trace_inc_metrics_context(RuleId, Action),
+    ReplyTo = {fun ?MODULE:inc_action_metrics/2, [IncCtx], #{reply_dropped => true}},
     case
         emqx_bridge_v2:send_message(
             BridgeType,
             BridgeName,
             Selected,
-            #{reply_to => ReplyTo, trace_ctx => maps:remove(action_id, TraceCtx)}
+            #{reply_to => ReplyTo, trace_ctx => TraceCtx}
         )
     of
         {error, Reason} when Reason == bridge_not_found; Reason == bridge_stopped ->
@@ -460,17 +460,31 @@ do_handle_action(
         Result ->
             Result
     end;
-do_handle_action(_RuleId, #{mod := Mod, func := Func} = Action, Selected, Envs) ->
+do_handle_action(RuleId, #{mod := Mod, func := Func} = Action, Selected, Envs) ->
     trace_action(Action, "call_action_function"),
     %% the function can also throw 'out_of_service'
     Args = maps:get(args, Action, []),
     Result = Mod:Func(Selected, Envs, Args),
-    TraceCtx = do_handle_action_get_trace_context(Action),
-    inc_action_metrics(TraceCtx, Result),
+    {_, IncCtx} = do_handle_action_get_trace_inc_metrics_context(RuleId, Action),
+    inc_action_metrics(IncCtx, Result),
     trace_action(Action, "call_action_function_result", #{result => Result}, debug),
     Result.
 
-do_handle_action_get_trace_context(Action) ->
+do_handle_action_get_trace_inc_metrics_context(RuleID, Action) ->
+    case emqx_trace:list() of
+        [] ->
+            %% As a performance/memory optimization, we don't create any trace
+            %% context if there are no trace patterns.
+            {undefined, #{
+                rule_id => RuleID,
+                action_id => Action
+            }};
+        _List ->
+            Ctx = do_handle_action_get_trace_inc_metrics_context_unconditionally(Action),
+            {maps:remove(action_id, Ctx), Ctx}
+    end.
+
+do_handle_action_get_trace_inc_metrics_context_unconditionally(Action) ->
     Metadata = logger:get_process_metadata(),
     StopAfterRender = maps:get(stop_action_after_render, Metadata, false),
     case Metadata of

apps/emqx_rule_engine/src/emqx_rule_sqltester.erl

@@ -28,7 +28,6 @@ apply_rule(
     RuleId,
     #{
         context := Context,
-        environment := Env,
         stop_action_after_template_rendering := StopAfterRender
     }
 ) ->
@@ -39,30 +38,32 @@ apply_rule(
         true ->
             %% test if the topic matches the topic filters in the rule
             case emqx_topic:match_any(InTopic, EventTopics) of
-                true -> do_apply_matched_rule(Rule, Context, Env, StopAfterRender);
-                false -> {error, nomatch}
+                true ->
+                    do_apply_matched_rule(
+                        Rule,
+                        Context,
+                        StopAfterRender
+                    );
+                false ->
+                    {error, nomatch}
             end;
         false ->
             case lists:member(InTopic, EventTopics) of
                 true ->
                     %% the rule is for both publish and events, test it directly
-                    do_apply_matched_rule(Rule, Context, Env, StopAfterRender);
+                    do_apply_matched_rule(Rule, Context, StopAfterRender);
                 false ->
                     {error, nomatch}
             end
     end.
 
-do_apply_matched_rule(Rule, Context, Env, StopAfterRender) ->
+do_apply_matched_rule(Rule, Context, StopAfterRender) ->
     update_process_trace_metadata(StopAfterRender),
-    Env1 =
-        case Env of
-            M when map_size(M) =:= 0 ->
-                %% Use the default environment if no environment is provided
-                default_apply_rule_environment();
-            _ ->
-                Env
-        end,
-    ApplyRuleRes = emqx_rule_runtime:apply_rule(Rule, Context, Env1),
+    ApplyRuleRes = emqx_rule_runtime:apply_rule(
+        Rule,
+        Context,
+        apply_rule_environment()
+    ),
     reset_trace_process_metadata(StopAfterRender),
     ApplyRuleRes.
 
@@ -80,16 +81,11 @@ reset_trace_process_metadata(true = _StopAfterRender) ->
 reset_trace_process_metadata(false = _StopAfterRender) ->
     ok.
 
-default_apply_rule_environment() ->
-    #{
-        headers => #{
-            protocol => mqtt,
-            username => undefined,
-            peerhost => {127, 0, 0, 1},
-            proto_ver => 5,
-            properties => #{}
-        }
-    }.
+%% At the time of writing the environment passed to the apply rule function is
+%% not used at all for normal actions. When it is used for custom functions it
+%% is first merged with the context so there does not seem to be any need to
+%% set this to anything else then the empty map.
+apply_rule_environment() -> #{}.
 
 -spec test(#{sql := binary(), context := map()}) -> {ok, map() | list()} | {error, term()}.
 test(#{sql := Sql, context := Context}) ->

apps/emqx_rule_engine/test/emqx_rule_engine_SUITE.erl

@@ -158,13 +158,13 @@ init_per_suite(Config) ->
     emqx_rule_funcs_demo:module_info(),
     application:load(emqx_conf),
     ok = emqx_common_test_helpers:start_apps(
-        [emqx, emqx_conf, emqx_rule_engine, emqx_auth, emqx_bridge],
+        [emqx_conf, emqx_rule_engine, emqx_auth, emqx_bridge],
         fun set_special_configs/1
     ),
     Config.
 
 end_per_suite(_Config) ->
-    emqx_common_test_helpers:stop_apps([emqx, emqx_conf, emqx_rule_engine, emqx_auth, emqx_bridge]),
+    emqx_common_test_helpers:stop_apps([emqx_conf, emqx_rule_engine, emqx_auth, emqx_bridge]),
     ok.
 
 set_special_configs(emqx_auth) ->

rel/i18n/emqx_rule_api_schema.hocon

@@ -66,12 +66,6 @@ test_context.desc:
 test_context.label:
 """Event Conetxt"""
 
-test_rule_environment.desc:
-"""The environment that will be passed to the rule when it is applied. A default environment will be used if no environment is given."""
-
-test_rule_environment.label:
-"""Event Environment"""
-
 stop_action_after_template_render.desc:
 """Set this to true if the action should be stopped after its template has been rendered (default is true)."""