PHP 5.5 FastCGI Caching

Question

I've implemented FastCGI caching on our site, and have seen great speed improvements. However the FastCGI cache key does not seem to be unique enough. If I login, my name appears in the header. However the next person to login still sees my name in the header, assuming the cache is still valid.

Is there a way to make the cache key unique on a per-user basis? Ideally using a unique identifier from the user's Cookies or a PHP Session? I tried implemented the answer below, but Nginx failed to restart.

Log in value from Set-Cookie header in nginx

Note my cache key looks like this:

fastcgi_cache_key "$scheme$request_method$host$request_uri";

Update: My thought is if I can parse the HTTP headers sent to Nginx, then I can grab the PHP SESSION ID and use that. However I cannot find an example of how to do this anywhere. Right now I have something like this, which doesn't work.

http_cookie ~* PHPSESSID=([0-9a-z]+) {
    set $ses_id $1;
}

Answer 1

I was able to solve the above problem using the Nginx ngx_http_userid_module. The hardest part was actually finding the module, implementing the solution was quite trivial.

I used their example configuration:

userid         on;
userid_name    uid;
userid_domain  example.com;
userid_path    /;
userid_expires 365d;
userid_p3p     'policyref="/w3c/p3p.xml", CP="CUR ADM OUR NOR STA NID"';

And then added the userid to my fastCGI cache key:

fastcgi_cache_key "$scheme$request_method$host$request_uri$uid_got";

Hopefully this answer helps someone discover this useful module quicker than I did.