Utilizing Nginx's FastCGI cache

Something I wasn't aware of until recently, the Nginx FastCGI module comes with a rather nifty caching component.

Basically via config you are able to control the caching of responses from your FastCGI backend(s) (e.g. PHP-FPM) straight to disk, with the next request for the same cache key (which is typically made up of your $scheme, $request_method and $request_uri - but can be controlled) then served up from disk cache via Nginx directly.

I have posted some boilerplate config to a Gist here:

https://gist.github.com/magnetikonline/10450786

Things of note:

• The target cache file path, shared memory size/use and GC timeout is set by fastcgi_cache_path
• Cache key is controlled via fastcgi_cache_key and can include anything in it's makeup that's available in Nginx variable land.
• Using a rewrite variable $fastcgi_skipcache and some if() conditions we can get quite complex as to what is in/out when it comes to adding content to the cache vs. passing through to your FastCGI backend.

Have had some really good success with this on a few highly trafficked, yet sluggish WordPress blogs of late with minimal code changes required within the apps themselves - including the use of custom HTTP headers with XMLHTTP requests and $http_[CUSTOM-HEADER] to control cache injection.

Well worth a look in.