openstack-ansible-security/doc/source/developer-notes/V-51369.rst

Although SELinux is available on Ubuntu 14.04, the policies aren't maintained as well as they are on Red Hat-based systems. The openstack-ansible project has chosen to use the more Ubuntu-compatible Linux security module, AppArmor.

AppArmor roles are configured in openstack-ansible to limit the chances of container breakout and the potential damage done in case it does occur.