Getting started with libvirt08 Nov 2016
Very recently I have been working on a platform to orchestrate VM creation and lifecycle management across a cluster of nodes with capacity, metadata, storage and network management. I was exploring stuff like KVM + QEMU and XEN when I read about libvirt and found it perfectly suiting my needs.
To start off with, KVM (Kernel-based Virtual Machine) is a virtualization infrastructure for the Linux kernel that turns it into a hypervisor, a software which enables us to run Virtual Machines on top of a host machine. XEN is another such hypervisor.
libvirt, on the other hand is an abstraction layer on top of the various hypervisor platforms with a nice API available to manage virtualization. We can choose to use any of the hypervisor backends that libvirt supports to create and manage virtual machines. The list of hypervisors supported by libvirt are listed below:
- KVM / QEMU
- User Mode Linux
- VMWare ESX and GSX
- VMWare workstation and Player
- Hyper V
- Parallels Workstation
Let’s start off with installing libvirt first. Since the workstations I use are ArchLinux and OSX, I will stick to these two platforms only (the installation instructions for other platforms are easily available).
On ArchLinux, you can install libvirt with a KVM backend by installing the following packages
sudo pacman -S libvirt qemu ebtables dnsmasq bridge-utils openbsd-netcat
By default, KVM is the default driver enabled.
On OSX, you can install libvirt by running
brew install libvirt
To ensure that the libvirt daemon is running, run the following command
sudo systemctl status libvirtd
Once the libvirt daemon is running you can use the command line client
virsh which comes included in the libvirt package to connect to the daemon.
Once inside the
virsh client, you can run a bunch of commands to consume the API.
- Getting the hypervisor hostname
virsh # hostname playstation
- Getting the node information
virsh # nodeinfo CPU model: x86_64 CPU(s): 4 CPU frequency: 1800 MHz CPU socket(s): 1 Core(s) per socket: 2 Thread(s) per core: 2 NUMA cell(s): 1 Memory size: 8066144 KiB
- Getting the version
virsh # version Compiled against library: libvirt 2.3.0 Using library: libvirt 2.3.0 Using API: QEMU 2.3.0 Running hypervisor: QEMU 2.7.0
You can use the
help command to get a list of all available commands.
In the next post in the libvirt series, I’ll start off with programmatically consuming the libvirt APIs.