[Rspamd] Use meta exporter to pipe meta data of ratelimited msg to Redis

data/conf/rspamd/local.d/metadata_exporter.conf

@@ -1,10 +1,26 @@
 rules {
-        QUARANTINE {
-                backend = "http";
-                url = "http://nginx:9081/pipe.php";
-                selector = "is_reject";
-                formatter = "default";
-                meta_headers = true;
-        }
+  QUARANTINE {
+    backend = "http";
+    url = "http://nginx:9081/pipe.php";
+    selector = "is_reject";
+    formatter = "default";
+    meta_headers = true;
+  }
+	RLINFO {
+		backend = "http";
+		url = "http://nginx:9081/pipe_rl.php";
+		selector = "ratelimited";
+		formatter = "json";
+	}
+}
+custom_select {
+  ratelimited = <<EOD
+return function(task)
+  local ratelimited = task:get_symbol("RATELIMITED")
+  if ratelimited then
+    return true
+  end
+  return
+end
+EOD;
 }
-