Remotely controllingvirtual machines with virsh

Engine Room toBridge

Article from ADMIN 07/2012

By Tim Schürmann

With the command-line tool virsh, a part of the libvirt library, you can query virtual machines to discover their state of health, launch or shut down virtual machines, and perform other tasks – all of which can be conveniently scripted.

The libvirt project has set the objective of creating a standardized management center for a variety of virtualization solutions and hypervisors [1]. Many administrators in production environments only know it as the colorful virt-manager front end, which manages virtual machines on Qemu/KVM. However, virt-manager isn't even part of the libvirt project, which only provides a handful of command-line programs, one of which is the overlooked but essential virsh.

Building Blocks

Like any other libvirt tool, virsh relies on the libvirt library, which in turn provides the interface to the libvirtd daemon. The daemon runs on the machine hosting the virtual machines, also known as a node, and controls the hypervisor operations (Figure 1), making libvirtd basically indispensable to administrators.

Figure 1: Virsh passes the commands on to the other libvirt package components.

After installing libvirt, you can immediately start using virsh – at least normally you can. Many distributions, two of them being Debian and Ubuntu, have offloaded the libvirt tools into a separate package. In this case, you need to install

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