This guide explains how to configure Apache under Debian in order to run PHP under the fastcgi module instead of mod_php. By default Apache loads mod_php for all file types and consumes more resources but with fastcgi we can configure Apache to pass just PHP files to the PHP interpreter.

The libapache2-mod-fastcgi module is needed that can be installed by editing /etc/apt/sources.list and then adding contrib and non-free to the default repository. For example:

deb http://uk.debian.org/debian/ jessie main contrib non-free
deb-src http://uk.debian.org/debian/ jessie main contrib non-free

First, disable the standard php5 module with:

a2dismod php5

After that, run aptitude update and then install the necessary packages:

aptitude install php5-fpm libapache2-mod-fastcgi apache2

Next, we create or overwrite the file at /etc/apache2/mods-available/fastcgi.conf with the following contents:

fastcgi.conf

<IfModule mod_fastcgi.c>
    AddType application/x-httpd-fastphp5 .php
    Action application/x-httpd-fastphp5 /php5-fcgi
    Alias /php5-fcgi /usr/lib/cgi-bin/php5-fcgi
    FastCgiExternalServer /usr/lib/cgi-bin/php5-fcgi -socket /var/run/php5-fpm.sock -pass-header Authorization
    <Directory /usr/lib/cgi-bin>
        Require all granted
    </Directory>
</IfModule>

Then, we enable all the necessary support modules:

a2enmod actions alias fastcgi

where:

• actions is needed for FPM
• alias is needed to create the PHP alias
• fastcgi is the PHP FastCGI module

PHP-FPM has to be started by issuing:

/etc/init.d/php5-fpm restart

and after that Apache2 can be started by issuing:

/etc/init.d/apache2 restart

Create a PHP file containing:

<?php phpinfo();

and open it in the browser. You should see on the first screen along the top:

Server API	FPM/FastCGI

which indicates that it is working.

In case you see:

Server API     Apache Handler 2.0

then it is not working - most likely you have forgotten to disable the standard PHP module (with a2dismod php5).

• Set a PCRE recursion limit.