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Using Libvirt with Python to manage virtual machines

Remote Diagnostics

Article from ADMIN 22/2014

By Thorsten Scherf

If you do not want to use any of the major management frameworks to manage your virtual machines, the Libvirt library for Python provides an alternative.

In enterprise environments, you often see extensive management frameworks used to manage the collection of virtual systems and other resources. If you want to right-size your approach and prefer to rely on the Libvirt virtualization framework instead, you can automate many tasks via its API.

I recently had such a case: A provisioning front end had been used to generate a variety of virtual systems on a number of hypervisors. I wanted to know when a machine was available on a host. Of course, I could have changed the front end so that a message was sent when a new system was installed, but, unfortunately, I did not have access to the provisioning system.

I could have turned to a management tool (virsh or virt-manager), but that's a fairly convoluted approach in the long run, especially if you are sitting in front of a workstation and the tools are not installed there. To solve the problem, I decided to simply send a request to the Libvirt API on the existing hypervisors and retrieve a list of active and inactive systems. The output can be garnished with arbitrary information, but I was just interested in seeing which systems were online and which were offline.

The virtualization framework offers a range of authentication methods. Because time is always short, I opted for a simple SSH-based login on the host systems. To do this, I created a virtuser account and defined an SSH key for the account at the same time. The user and the SSH key are managed via a central FreeIPA system (Figure 1).

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