fix: return 503 if dashboard's router not ready

apps/emqx_dashboard/src/emqx_dashboard_middleware.erl

@@ -23,7 +23,7 @@
 execute(Req, Env) ->
     case check_dispatch_ready(Env) of
         true -> add_cors_flag(Req, Env);
-        false -> {stop, cowboy_req:reply(503, Req)}
+        false -> {stop, cowboy_req:reply(503, #{<<"retry-after">> => <<"15">>}, Req)}
     end.
 
 add_cors_flag(Req, Env) ->

apps/emqx_management/src/emqx_mgmt_api_status.erl

@@ -33,18 +33,26 @@ init(Req0, State) ->
 %%--------------------------------------------------------------------
 
 running_status() ->
-    BrokerStatus =
+    case emqx_dashboard_listener:is_ready(timer:seconds(20)) of
+        true ->
+            BrokerStatus = broker_status(),
+            AppStatus = application_status(),
+            Body = io_lib:format("Node ~ts is ~ts~nemqx is ~ts", [node(), BrokerStatus, AppStatus]),
+            {200, #{<<"content-type">> => <<"text/plain">>}, list_to_binary(Body)};
+        false ->
+            {503, #{<<"retry-after">> => <<"15">>}, <<>>}
+    end.
+
+broker_status() ->
     case emqx:is_running() of
         true ->
             started;
         false ->
             stopped
-        end,
+    end.
-    AppStatus =
+
+application_status() ->
     case lists:keysearch(emqx, 1, application:which_applications()) of
         false -> not_running;
         {value, _Val} -> running
-        end,
+    end.
-    Status = io_lib:format("Node ~ts is ~ts~nemqx is ~ts", [node(), BrokerStatus, AppStatus]),
-    Body = list_to_binary(Status),
-    {200, #{<<"content-type">> => <<"text/plain">>}, Body}.