message: add a dynamic.director.
diff: @@ -19,9 +19,20 @@ acl purge {
  "192.168.0.0"/16;
  }
  +sub vcl_init {
  + new www_dir = dynamic.director(
  + port = "${VARNISH_BACKEND_PORT:-8080}",
  + probe = www_probe,
  + whitelist = purge,
  + ttl = 60s);
  + }
  +
  +
  # This configuration is optimized for Drupal hosting:
  # Respond to incoming requests.
  sub vcl_recv {
  + set req.backend_hint = www_dir.backend("${VARNISH_BACKEND_HOST:-nginx}");
  +
  if (req.url ~ "^/varnish_status$") {
  return (synth(200,"OK"));
  }
  