[Nginx] Custom 502

data/conf/nginx/site.conf

@@ -210,4 +210,9 @@ server {
   }
 
   include /etc/nginx/conf.d/site.*.custom;
+
+  error_page 502 @awaitingupstream;
+  location @awaitingupstream {
+    rewrite ^(.*)$ /_status.502.html break;
+  }
 }