add healthcheck for dns

docker-compose.yml

@@ -125,7 +125,11 @@ services:
       dns-net:
     dns: 
       - 127.0.0.1
-
+    healthcheck:
+      test: ["CMD", "nslookup", "server1.mrhossa.de", "127.0.0.1"]
+      interval: 30s
+      timeout: 5s
+      retries: 3
 networks:
   docker-net:
     driver: bridge