Question

Say I don’t have mod_deflate compiled into apache, and I don’t feel like recompiling right now. What are the downsides to a manual approach, e.g. something like:

AddEncoding x-gzip .gz
RewriteCond %{HTTP_ACCEPT_ENCODING} gzip
RewriteRule ^/css/styles.css$ /css/styles.css.gz

(Note: I’m aware that the specifics of that RewriteCond need to be tweaked slightly)

Answer 1

Another alternative would be to forward everything to a PHP script, which gzips and caches everything on the fly. On every request, it would compare timestamps with the cached version and return that if it’s newer than the source file. With PHP, you can also overwrite the HTTP Headers, so it is treated properly as if it was GZIPed by Apache itself.

Something like this might do the job for you:

.htaccess

RewriteEngine On
RewriteRule ^(css/styles.css)$ cache.php?file=$1 [L]

cache.php:

<?php
// Convert path to a local file path (may need to be tweaked)
cache($_GET['file']);

// Return cached or raw file (autodetect)
function cache($file)
{
  // Regenerate cache if the source file is newer
  if (!is_file($file.'.gz') or filemtime($file.'.gz') < filemtime($file)) {
    write_cache($file);
  }

  // If the client supports GZIP, send compressed data
  if (!empty($_SERVER['HTTP_ACCEPT_ENCODING']) and strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== false) {
    header('Content-Encoding: gzip');
    readfile($file.'.gz');
  } else { // Fallback to static file
    readfile($file);
  }
  exit;
}

// Saved GZIPed version of the file
function write_cache($file)
{
  copy($file, 'compress.zlib://'.$file.'.gz');
}

You will need write permissions for apache to generate the cached versions. You can modify the script slightly to store cached files in a different place.

This hasn’t been extensively tested and it might need to be modified slightly for your needs, but the idea is all there and should be enough to get you started.