proxy_cache img_cache;
proxy_cache_key "$scheme://$host$request_uri$is_args$args";
proxy_cache_valid 200 301 302 30d;
proxy_cache_valid 404 1h;
proxy_cache_use_stale error timeout updating;
proxy_cache_lock on;
proxy_cache_background_update on;
expires max;
access_log off;
add_header Cache-Control "public, immutable";