Add [](bracket). IPv6 address expression is also changed in ver 3.0.x.

slapos/recipe/generic_varnish/template/default.vcl.in

@@ -5,7 +5,7 @@
 #server.
 #
 backend default {
-  .host = "%(backend_ip)s";
+  .host = "%(backend_server)s";
   .port = "%(backend_port)s";
   .probe = {
            .timeout = 30s;