anchor.diff:  # ************************************************************
   probe backend_health_check {
       .url = "<%= @health_check_url %>";
  -    .url = "/ping.txt"
       .timeout = <%= @health_check_timeout %>;
  -    .timeout = 300ms;
       .interval = <%= @health_check_interval %>;
  -    .interval = 1s;
       .window = <%= @health_check_window %>;
  -    .window = 10;
       .threshold = <%= @health_check_threshold %>;
  -    .threshold = 6;
       .expected_response = <%= @health_check_expected_response %>;
  -    .expected_response = 200;
   }
   
   # ************************************************************
  
positive.code:     .host = "<%= v[0] %>";
      .port = "<%= v[1] %>";
      .first_byte_timeout = <%= @first_byte_timeout %>;
  # This backend is used for saint mode. Unless you know what you're doing
  # DO NOT REMOVE
  }
  <% end -%>
  
  
negative.code: # Saint Mode Backend
  # https://www.varnish-software.com/static/book/Saving_a_request.html#example-evil-backend-hack
  # ************************************************************
  backend fail {
      .host = "127.0.0.1";
      .port = "12871";
      .probe = {
          .url = "/fail";
          .initial = 0;
          .interval = 1d;
      }
  }
  
  # ************************************************************
  # Director
  