diff --git a/apps/iot/src/iot_mqtt_publisher.erl b/apps/iot/src/iot_mqtt_publisher.erl
index 2997a1c..cacb7ad 100644
--- a/apps/iot/src/iot_mqtt_publisher.erl
+++ b/apps/iot/src/iot_mqtt_publisher.erl
@@ -69,6 +69,7 @@ init([]) ->
     {stop, Reason :: term(), NewState :: #state{}}).
 handle_call({publish, ReceiverPid, Topic, Message, Qos}, _From, State = #state{conn_pid = ConnPid, inflight = InFlight}) ->
     %% [{qos, Qos}, {retain, true}]
+    lager:debug("[iot_mqtt_publisher] will publish message: ~p, topic: ~p, qos: ~p", [Message, Topic, Qos]),
     case emqtt:publish(ConnPid, Topic, #{}, Message, [{qos, Qos}]) of
         {ok, PacketId} ->
             Ref = make_ref(),