Web Accelerating Cache¶

Module: mod_cache

• Table of contents
• Web Accelerating Cache
  • Description
  • Installation
  • Options

Description¶

mod_cache site comes back again since feb. 29, 2008
mod_cache provides a shared web cache for mod_proxy and uses a configuration similar to Squid Cache. mod_cache has several key benefits:

• Simple: mod_cache sets lighttpd flags between request handling stages. The request is then handled by mod_staticfile, mod_proxy, or other modules.
• Robust: mod_cache stores caches to the filesystem rather than to memory in order to avoid memory leaks/exhaustion.
• Fast: Lighttpd uses the Sendfile system call, which writes the file to the network interface directly.
• Powerful: mod_cache can be used in conjunction with other lighttpd plugins (except mod_deflate and mod_secdownload). For example; using mod_compress to compress cached files, using mod_access/mod_trigger_b4_dl to implement anti-hot-link restrictions, or using mod_flv_streaming to do native flv file streaming.

With the shared web cache, mod_proxy is able to deliver content from the local cache without having to re-download bulky files, thus simultaneously increasing the speed from the user's perspective while reducing bandwidth up-stream of the server.

This is not intended to be a reverse-proxy as one is rarely useful with Lightttpd, as Lighttpd is designed to handle a large number of concurrent requests with minimal resource usage by loading external applications (eg. FastCGI) only when needed, and gracefully handling slow user transfers without blocking. For more information on optimizing the performance of Lighttpd, see: http://trac.lighttpd.net/trac/wiki/Docs:Performance

Installation¶

This module is a 3rd party module and is not included in the official distribution. You can download the patch from here:

• For lighttpd 1.4.13: http://www.linux.com.cn/modcache/lighttpd-1.4.13.mod_cache.v1.2.patch
• For lighttpd 1.4.18: http://www.linux.com.cn/modcache/lighttpd-1.4.18.modcache.v.1.4.3.patch
• For lighttpd 1.4.19: http://www.linux.com.cn/modcache/lighttpd-1.4.19.modcache.v.1.6.0.patch

or you can download the following patched versions of lighttpd:

• 1.4.26: http://lighttpd-improved.googlecode.com/files/lighttpd-1.4.26.modcache.v.1.8.3-2.tar.gz

The PCRE library is needed to build mod_cache.

Always check for updates before attemping to install this or any other 3rd party module.

If the official source is not available there is a google group dedicated to mod_cache: http://groups.google.com/group/mod_cache

Options¶

See [http://code.google.com/p/lighttpd-improved/]

cache.bases
directory arrays which want to save cache files.

e.g.:
cache.bases=("/data/cache", "/data2/cache")

Default: not set

cache.enable
enable or disable mod_cache.

e.g.:

    cache.enable = "disable" 
    $HTTP["host"] == "video.example.org" {
      cache.enable = "enable" 
    }

Default: enable

cache.domains
domain pcre regex arrays which mod_cache will cache.

e.g.:
cache.domains = ("mydomain.com$")

Default: not set (all domains are cached)

cache.support-queries
ignore '?' in request url or not.

e.g.:
cache.support-queries = "enable" # mod_cache treats "/uri?q1" or "/uri?q2" as "/uri". *

Default: disable.

cache.debug
writes mod_cache debugging messages to error.log or not

Default: disable.

cache.purge-host
PCRE regex hosts IP which are allowed to PURGE cache file

e.g.:

   cache.purge-host = "^(192\.168\.|222\.120\.35\.)" # Allow PURGE from 192.168/16 and 222.120.35/24, plus hardcoded 10/8 and 127.0.0.1

Default: not set (10/8 and 127.0.0.1 are hardcoded to ip lists which allow to PURGE)

cache.ignore-hostname
don't include hostname in cache saving filename

Default: disable.

cache.refresh-pattern
arrays of "url_pcre_regex" => "minutes options". Zero minute means cache forever. multi options are allowed.

refresh-pattern options are:

Option	Description
ignore-reload	do not update cache when browser sends 'Cache-Control: no-cache' header
update-on-refresh	update cache when browser sends 'Cache-Control: no-cache' header
override-expire	ignore backend's 'Expire' header while determining whether to cache
ignore-cache-control-header	ignore backend's 'Cache-Control' headers while determining whether to cache
no-expire-header	do not set expires header on matched uri. without this options mod_cache set expire header based refresh-pattern rule
fetchall-for-range-request	download all content of file if browser sends 'Range: xxx-yyybytes' header. it is useful for multi-thread downloaders(such as flashget)
flv-streaming	to work with mod_flv_streaming
nocache	do not cache matched url

Examples