anchor.diff:      set req.backend = whitehall;
     } else if (req.url ~ "^/maternity(\.xml|\.json|\.ics)?(\?.*|)$|^/paternity(\.xml|\.json|\.ics)?(\?.*|)$") {
       set req.backend = planner;
  +  } else if (req.url ~ "^/designprinciples") {
  +    set req.backend = designprinciples;
     } else {
       set req.backend = frontend;
     }
  
positive.code:   <% frontend_hosts.count.times do |i| %>
    {
    .backend = smartanswers_<%= i %>;
    }
    <% end %>
  }
  
negative.code:     .threshold = 3;
    }
  }
  
  backend designprinciples_<%= i %> {
    .host = "<%= host %>";
    .port = "8085";
    .host_header = "designprinciples.<%= govuk_platform %>.alphagov.co.uk";
    .probe = {
      .url = "/";
      .interval = 5s;
      .timeout = 1s;
      .window = 5;
      .threshold = 3;
    }
  }
  
  <% end %>
  
  director frontend round-robin {
  