proxy_cache_convert_head off;
proxy_cache_methods GET HEAD;
proxy_cache_key $scheme$request_method$proxy_host$request_uri;
proxy_cache cache_std;
proxy_cache_valid 200 120m;
proxy_cache_valid 404 500 502 503 504 20s;
proxy_no_cache $no_cache;
proxy_cache_use_stale error timeout http_500 http_502 http_503 http_504;
add_header X-Proxy-Cache $upstream_cache_status;
