anchor.diff:        # Caching
         proxy_cache "proxy_cache_zone";
         proxy_cache_lock on;
  -      proxy_cache_valid 200 1d;
  +      proxy_cache_valid 200 2d;
         proxy_cache_valid 404 15m;
         # Serve stale cache on errors or if updating
         proxy_cache_use_stale error timeout updating http_404 http_500 http_503 http_504;
         # If in cache as stale, serve stale and update in background
         proxy_cache_background_update on;
  +      # Workaround nginx async bug which causes stale cache replies to wait for the async backend cache update reply (seen in v1.16.0)
  +      keepalive_requests 0;
         # Enable revalidation using If-Modified-Since and If-None-Match for stale items
         proxy_cache_revalidate on;
  -      proxy_cache_min_uses 8;
  +      proxy_cache_min_uses 4;
   
         add_header x-cache-status $upstream_cache_status;
   <% end -%>
  
positive.code:       return 404;
      }
  
  <% for i in 0..15 do %>
  <% if i == 0 -%>
      # Default Fallback Location Handler (lowest)
      location / {
  
negative.code:       proxy_http_version 1.1;
        proxy_set_header Connection '';
  
        proxy_connect_timeout 20s;
  
        # Replace host header.
        proxy_set_header Host 'tile.openstreetmap.org';
  