Add configuration for sys_heartbeat

etc/emqx.conf

@@ -1878,6 +1878,14 @@ plugins.expand_plugins_dir = {{ platform_plugins_dir }}/
 ## Default: 1m, 1 minute
 broker.sys_interval = 1m
 
+## System heartbeat interval of publishing following heart beat message:
+##  - "$SYS/brokers/<node>/uptime"
+##  - "$SYS/brokers/<node>/datetime"
+##
+## Value: Duration
+## Default: 30s
+broker.sys_heartbeat = 30s
+
 ## Enable global session registry.
 ##
 ## Value: on | off

priv/emqx.schema

@@ -1807,6 +1807,11 @@ end}.
   {default, "1m"}
 ]}.
 
+{mapping, "broker.sys_heartbeat", "emqx.broker_sys_heartbeat", [
+  {datatype, {duration, ms}},
+  {default, "30s"}
+]}.
+
 {mapping, "broker.enable_session_registry", "emqx.enable_session_registry", [
   {default, on},
   {datatype, flag}

src/emqx_sys.erl

@@ -28,6 +28,7 @@
         , datetime/0
         , sysdescr/0
         , sys_interval/0
+        , sys_heatbeat_interval/0
         ]).
 
 -export([info/0]).
@@ -92,6 +93,11 @@ datetime() ->
 sys_interval() ->
     application:get_env(?APP, broker_sys_interval, 60000).
 
+%% @doc Get sys heatbeat interval
+-spec(sys_heatbeat_interval() -> pos_integer()).
+sys_heatbeat_interval() ->
+    application:get_env(?APP, sys_heartbeat, 30000).
+
 %% @doc Get sys info
 -spec(info() -> list(tuple())).
 info() ->
@@ -111,7 +117,7 @@ init([]) ->
     {ok, heartbeat(tick(State))}.
 
 heartbeat(State) ->
-    State#state{heartbeat = start_timer(timer:seconds(1), heartbeat)}.
+    State#state{heartbeat = start_timer(sys_heatbeat_interval(), heartbeat)}.
 tick(State) ->
     State#state{ticker = start_timer(sys_interval(), tick)}.