anchor.diff:  # 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 = backend_health_check; }
  +backend fail {
  +    .host = "127.0.0.1";
  +    .port = "12871";
  +    .probe = {
  +        .url = "/fail";
  +        .initial = 0;
  +        .interval = 1d;
  +    }
  +}
   
   # ************************************************************
   # Director
  
positive.code: # ************************************************************
  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;
  }
  
  # ************************************************************
  
negative.code:     .host = "<%= v[0] %>";
      .port = "<%= v[1] %>";
      .first_byte_timeout = <%= @first_byte_timeout %>;
      .probe = backend_health_check;
  }
  <% end -%>
  
  