Rewrite rule for cache busting URLs

[bkirkbri]

Our application uses versioned URLs like http://domain.com/r123456789/resource/uri to allow for aggressive caching and easy cache invalidation.

To get this working in nginx, I currently have a config like this:

[code]
#################################################
set $cache_control '';

location ~ ^/r\d+/ {
    set $cache_control 'public, max-age=2592000'; # 30 days
    rewrite ^/r\d+(/.*)$ $1 last;
}

location /some/resources {
    if ( $cache_control ) {
        add_header Cache-Control $cache_control;
    }
    alias /path/to/resources;
}

location /some/other/resource {
    if ( $cache_control ) {
        add_header Cache-Control $cache_control;
    }
    alias /some/other/path;
}
#################################################
[/code]

Is this a bad idea?  Likely to fail in the future?  Anyone know a better way?

Could the HTTP Headers module be improved to allow "expires" or "add_header" to be used inside an "if" condition?

Thanks in advance!

Best,
Brian

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,96334,96334#msg-96334