fix: add push_gateway_server's validator

apps/emqx_prometheus/src/emqx_prometheus_schema.erl

@@ -26,7 +26,8 @@
     fields/1,
     desc/1,
     translation/1,
-    convert_headers/1
+    convert_headers/1,
+    validate_push_gateway_server/1
 ]).
 
 namespace() -> "prometheus".
@@ -41,6 +42,7 @@ fields("prometheus") ->
                 #{
                     default => "http://127.0.0.1:9091",
                     required => true,
+                    validator => fun ?MODULE:validate_push_gateway_server/1,
                     desc => ?DESC(push_gateway_server)
                 }
             )},
@@ -158,6 +160,12 @@ convert_headers(Headers) when is_map(Headers) ->
 convert_headers(Headers) when is_list(Headers) ->
     Headers.
 
+validate_push_gateway_server(Url) ->
+    case uri_string:parse(Url) of
+        #{scheme := S} when S =:= "https" orelse S =:= "http" -> ok;
+        _ -> {error, "Invalid url"}
+    end.
+
 %% for CI test, CI don't load the whole emqx_conf_schema.
 translation(Name) ->
     emqx_conf_schema:translation(Name).

apps/emqx_prometheus/test/emqx_prometheus_api_SUITE.erl

@@ -92,6 +92,12 @@ t_prometheus_api(_) ->
     NewConf1 = Conf#{<<"enable">> => (not Enable)},
     {ok, _Response3} = emqx_mgmt_api_test_util:request_api(put, Path, "", Auth, NewConf1),
     ?assertEqual((not Enable), undefined =/= erlang:whereis(emqx_prometheus)),
+
+    ConfWithoutScheme = Conf#{<<"push_gateway_server">> => "127.0.0.1:8081"},
+    ?assertMatch(
+        {error, {"HTTP/1.1", 400, _}},
+        emqx_mgmt_api_test_util:request_api(put, Path, "", Auth, ConfWithoutScheme)
+    ),
     ok.
 
 t_stats_api(_) ->