I recently updated the Memcached WP Object Cache plugin to use the Memcached PHP extension – it currently uses the Memcache extension. My plugin is called Memcached Redux, and it’s delicious. The Memcached PHP extension implements methods from libmemcached, the C / C++ Memcached library.

Installing the extension on MacPorts is beyond easy:

port install php5-memached

Installing on Amazon EC2 instance running CentOS 5 is WAY more esoteric. I spent about 2 hours mucking around until I figured it out, so here it is (this assumes you are already using memcached and have libevent, libzlib, etc installed):

cd /etc/yum.repos.d/
wget http://rpms.famillecollet.com/remi-enterprise.repo
wget http://syslogserver.googlecode.com/files/epel-release-5-3.noarch.rpm
wget http://rpms.famillecollet.com/enterprise/remi-release-5.rpm
rpm -Uvh remi-release-5*.rpm epel-release-5*.rpm
yum --enablerepo=remi install libmemcached*
pecl install memcached

vi /etc/php.ini

// (under Dynamic Extensions) Add "extension=memcached.so":

extension=apc.so
extension=http.so
extension=memcache.so
extension=memcached.so

Servers have to be restarted – this has be done before code is deployed or the class won’t exist, which will cause a fatal error.

This process looks harmless, but I had to read 3.7 million blog posts before I found the right path forward.