OpenStack service specifics
In this section, we'll walk through each of the OpenStack services and outline the H/A strategy for them. While most of the services can be configured as Active/Active behind a load balancer, some of them must be configured as Active/Passive and others may be configured as Active/Passive. Some of the configuration is dependent on a particular version of OpenStack as well, especially, Ceilometer, Heat, and Neutron. The following details are current as of the Liberty release of OpenStack.
OpenStack web services
As a general rule, all of the web services and the Horizon dashboard may be run Active/Active. These include the API services for Keystone, Glance, Nova, Cinder, Neutron, Heat, and Ceilometer. The scheduling services for Nova, Cinder, Neutron, Heat, and Ceilometer may also be deployed Active/Active. These services do not require a load balancer, as they respond to requests on the message bus.
The only web service which must be run Active/Passive is the Ceilometer...
