Large OpenStack environments usually require Keystone to handle a huge amount of authorization and authentication requests as Keystone is invoked on almost every OpenStack operation. To improve the scale Keystone can handle in heavy load environments we can configure the Keystone caching mechanism. The caching mechanism can store Tokens, User Identities, and Roles instead of retrieving them from a remote store. Keystone supports caching all configurable subsystems using a caching backend mechanism.
In this recipe, we configure Keystone to use Memcached caching service as a backend plugin for caching Keystone. We will need to install and configure the Memcached service first.
memcachedservice with dependent packages:
[root@controller ~]# yum install -y memcached memcached-selinux
[root@controller ~]# vi /etc/sysconfig/memcached
Make sure of the following settings: