{{tag>nginx webserver cache}}

====== Nginx caching ======
Example configuration of caching.

Below should be in http context somewhere
<code nginx>
proxy_cache_path /var/cache/nginx/mycache
  levels=1:2 keys_zone=de:100M max_size=1G;

</code>

Below is valid in http, server, location contexts.

<WRAP center round important 60%>
You might want to add ''$http_user_agent'' to cache key below to avoid a situation where for example, a mobile site will be served to desktop users if that site has been cached first.
</WRAP>

<code nginx>
    # caching doesn't work without proxy buffering
    proxy_buffering on;

    proxy_cache mycache;
    proxy_cache_key $scheme$proxy_host$uri$is_args$args;
    # caches for responses with status code 200, 301, and 302
    proxy_cache_valid 1d;
    # cache for any other including errors
    proxy_cache_valid any 1m;
    proxy_cache_min_uses 2;
    # bypass cache by providing query arg nocache=1
    proxy_cache_bypass $arg_nocache;
    proxy_cache_lock on;
    proxy_cache_background_update on;
    proxy_cache_use_stale error timeout updating
      http_500 http_502 http_503 http_504;

    add_header x-nginx-cache-status $upstream_cache_status;

    proxy_ignore_headers Cache-Control;

</code>

The proxied backend might send some ''cache-control'' headers on its own like with values like ''private, no-cache, no-store, max-age=0, must-revalidate''. 
We need to discard this. You might also need to ignore headers like ''Expires'' and ''X-Accel-Expires''.

The response header ''x-nginx-cache-status'' should say "HIT" if the configuration is correct.

====== Tested on ======
  * nginx/1.26.0

====== See also ======

====== References ======
  * http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_cache_bypass
  * https://stackoverflow.com/questions/9230812/nginx-as-cache-proxy-not-caching-anything
  * https://dzx.fr/blog/how-to-configure-reverse-proxy-caching-with-nginx/
  * https://www.mnot.net/cache_docs/
  * https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control