Fig. 1: Redundant MySQL Server nodes using Pacemaker, Corosync and DRBD.
If automation is required, Vagrant and Puppet seem to be the most adequate tools to implement it. What about automatic installation of High Availability database servers? As part of our Cloud Dependability efforts, the ICCLab works on automatic installation of High Availability systems. One such HA system is a MySQL Server – combined with DRBD, Corosync and Pacemaker.
In this system the server-logic of the MySQL Server runs locally on different virtual machine nodes, while all database files are stored on a clustered DRBD-device which is distributed on all the nodes. The DRBD resource is used by Corosync which acts as resource layer for Pacemaker. If one of the nodes fails, Pacemaker automagically restarts the MySQL server on another node and synchronizes the data on the DRBD device. This combined DRBD and Pacemaker approach is best practice in the IT industry.
At ICCLab we have developed an automatic installation script which creates 2 virtual machines and configures MySQL, DRBD, Corosync and Pacemaker on both machines. The automated installation script can be downloaded from Github.
Like us in the ICCLab, you have likely spent lots of time researching the best means to deploy OpenStack and you’ve decided upon a particular method (at the ICCLab we use foreman and puppet). You’ve implemented OpenStack with your chosen deployment plan and technologies and you now have an operational OpenStack cluster. The question you now have to ask is:
“How do I test that all functionality is operating correctly?”
You could certainly take the time to write a suite of tests using the various OpenStack python clients and maintain those. However there is an OpenStack project already available that can save you a lot of time. OpenStack Tempest is a project and suite that comprises of a set of integration tests. Tempest is used to validate the OpenStack code base through it’s integration with Jenkins (continuous integration server). Tempests calls against OpenStack service API endpoints and uses the python unittest2 and nosetest frameworks at its core.
If you wish to experiment with Tempest locally, try it out with devstack. Devstack automatically configures Tempest for use with it. To ease things, simply use vagrant-devstack (README here) do the following:
You will now see quite an amount of tests being run against your devstack installation. It will take time! If you wish to integrate Tempest with your Jenkins CI server see information on devstack gate. There is also a Tempest Jenkins plugin. Finally, if you wish to run Tempest against a “real” installation of OpenStack you will need to configure the Tempest configuration file (etc/tempest.conf) and change the relevant information (more here).