Old version 1.4.xx has mod_fastcgi for PHP. This module has been replaced by mod_proxy_backend_fastcgi and mod_proxy_core in Lighttpd 1.5.xx.

FastCGI was developed by FastCGI and is a binary container around HTTP requests which reduces the parsing overhead.

FastCGI used for both PHP and rails application. In this small howto I will explain howto configure PHP under Lighttpd 1.5.xx.

Required softwares

[a] Make sure you have Lighttpd v1.5.xx installed

[b] spawn-fcgi binary (part of lighttpd software) to spawns fastcgi processes. It is used to spawn remote/local FastCGI processes such as PHP or ruby.

[c] PHP compiled / installed as fastcgi. Type the following command to verify that php is installed as fastcgi binary (look for cgi-fcgi word):
$ php-cgi -v
OR
$ php -v
Output:

PHP 5.1.6 (cgi-fcgi) (built: Mar  9 2007 07:25:36)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies

mod_proxy_backend_fastcgi configuration

Open configuration file /etc/lighttpd/lighttpd.conf
# vi /etc/lighttpd/lighttpd.conf
Make sure following modules are loaded:
server.modules += ( "mod_proxy_core", "mod_proxy_backend_fastcgi" )

Configure fastcgi PGP module by appending following configuration directives:

$HTTP["url"] =~ "\.php$" {
        proxy-core.balancer = "round-robin"
        proxy-core.allow-x-sendfile = "enable"
        proxy-core.check-local = "enable"
        proxy-core.protocol = "fastcgi"
        proxy-core.backends = ( "unix:/tmp/php-fastcgi.sock" )
        proxy-core.max-pool-size = 16
}

Save and close the file.

Task: Start lighttpd

Type the following command to swap php using spawn-fcgi:
# /usr/bin/spawn-fcgi -s /tmp/php-fastcgi.sock -f /usr/bin/php-cgi -u lighttpd -g lighttpd -C 5 -P /var/run/spawn-fcgi.pid

Start/restart lighttpd:
# /etc/init.d/lighttpd start

Task: Stop lighttpd

Type the following command:
# /etc/init.d/lighttpd stop
Kill external php process:
# killall php-cgi

Task: Patch lighttpd init startup script

Since lighttpd uses external binary to swap php or ruby application you need to add stop and start functionality by patching /etc/init.d/lighttpd file. You can grab my /etc/init.d/lighttpd file .
# cd /etc/init.d/
# mv lighttpd lighttpd.old
# wget http://www.cyberciti.biz/files/lighttpd/1.5.0/lighttpd.init.d.txt
# mv lighttpd.init.d.txt lighttpd
# chmod +x lighttpd