[[s-ceilometer-agent-central]]
==== Highly available Ceilometer Central Agent

Ceilometer is the metering service in OpenStack.
Central Agent polls for resource utilization statistics for resources not tied
to instances or compute nodes.

NOTE: Due to limitations of a polling model, a single instance of this agent
can be polling a given list of meters. In this setup, we install this service
on the API nodes also in the active / passive mode.


Making the Ceilometer Central Agent service highly available in active / passive mode involves
managing its daemon with the Pacemaker cluster manager.

NOTE: You will find at http://docs.openstack.org/developer/ceilometer/install/manual.html#installing-the-central-agent[this page]
the process to install the Ceilometer Central Agent.


===== Adding the Ceilometer Central Agent resource to Pacemaker

First of all, you need to download the resource agent to your system:

----
cd /usr/lib/ocf/resource.d/openstack
wget https://raw.github.com/madkiss/openstack-resource-agents/master/ocf/ceilometer-agent-central
chmod a+rx *
----

You may then proceed with adding the Pacemaker configuration for
the Ceilometer Central Agent resource. Connect to the Pacemaker cluster with +crm
configure+, and add the following cluster resources:

----
include::includes/pacemaker-ceilometer_agent_central.crm[]
----

This configuration creates

* +p_ceilometer-agent-central+, a resource for manage Ceilometer Central Agent service

+crm configure+ supports batch input, so you may copy and paste the
above into your live pacemaker configuration, and then make changes as
required.

Once completed, commit your configuration changes by entering +commit+
from the +crm configure+ menu. Pacemaker will then start the Ceilometer Central Agent
service, and its dependent resources, on one of your nodes.

===== Configuring Ceilometer Central Agent service

Edit +/etc/ceilometer/ceilometer.conf+ :
----
# We use API VIP for Identity Service connection :
os_auth_url=http://192.168.42.103:5000/v2.0

# We send notifications to High Available RabbitMQ :
notifier_strategy = rabbit
rabbit_host = 192.168.42.102

[database]
# We have to use MySQL connection to store datas :
sql_connection=mysql://ceilometer:password@192.168.42.101/ceilometer
----