How do I add Cache Control expires header to images?

Question

I'm trying to speed up things on my site. YSlow alerts me that my images lack expires headers. But how do i apply such headers on images?

My application is based upon the zend framework. The images are stored as well images on a folder, how would I be able to set up expires headers for them?

Answer 1

I ran into the same problem yesterday...

1. Make sure you have the right headers set in the action that generates the image.
2. You have to add memorize_headers with 'Content-Type' to the frontendOptions and for performance also 'Cache-Control' and whatever headers you want to set...

So the example for Zend_Cache_Frontend_Page from http://framework.zend.com/manual/en/zend.cache.frontends.html it would look like this:

$frontendOptions = array(
   'lifetime' => 7200,
   'debug_header' => true, // for debugging
   'regexps' => array(
       // cache the whole IndexController
       '^/$' => array('cache' => true),

       // cache the whole IndexController
       '^/index/' => array('cache' => true),

       // we don't cache the ArticleController...
       '^/article/' => array('cache' => false),

       // ... but we cache the "view" action of this ArticleController
       '^/article/view/' => array(
           'cache' => true,

           // and we cache even there are some variables in $_POST
           'cache_with_post_variables' => true,

           // but the cache will be dependent on the $_POST array
           'make_id_with_post_variables' => true
       )
   ),
    'memorize_headers' => array(
        'Content-Type',
        'Cache-Control',
        'Expires',
        'Pragma',
   )
);

$backendOptions = array(
    'cache_dir' => '/tmp/'
);

// getting a Zend_Cache_Frontend_Page object
$cache = Zend_Cache::factory('Page',
                             'File',
                             $frontendOptions,
                             $backendOptions);

$cache->start();