SUSE Linux Enterprise Server Documentation › Virtualization Guide › Managing Virtual Machines with libvirt › Overview
ContentsContents
Virtualization Guide
  1. About This Manual
  2. I Introduction
    1. 1 Virtualization Technology
    2. 2 Introduction to Xen Virtualization
    3. 3 Introduction to KVM Virtualization
    4. 4 Introduction to Linux Containers
    5. 5 Virtualization Tools
    6. 6 Installation of Virtualization Components
    7. 7 Supported Guests, Hosts and Features
  3. II Managing Virtual Machines with libvirt
    1. 8 Overview
    2. 9 Guest Installation
    3. 10 Basic VM Guest Management
    4. 11 Connecting and Authorizing
    5. 12 Managing Storage
    6. 13 Configuring Virtual Machines
    7. 14 Administrating VM Guests
    8. 15 Save and Restore of Virtual Machines
  4. III Common Tasks
    1. 16 VM Guest Clock Settings
    2. 17 libguestfs
  5. IV Managing Virtual Machines with Xen
    1. 18 Setting Up a Virtual Machine Host
    2. 19 Virtual Networking
    3. 20 Managing a Virtualization Environment
    4. 21 Block Devices in Xen
    5. 22 Virtualization: Configuration Options and Settings
    6. 23 Administration Tasks
    7. 24 XenStore: Configuration Database Shared between Domains
    8. 25 Xen as a High-Availability Virtualization Host
  6. V Managing Virtual Machines with QEMU
    1. 26 QEMU Overview
    2. 27 Guest Installation
    3. 28 Running Virtual Machines with qemu-system-ARCH
    4. 29 KVM Disk Cache Modes
    5. 30 Administrating Virtual Machines with QEMU Monitor
  7. VI Managing Virtual Machines with LXC
    1. 31 Linux Containers
    2. 32 Migration from LXC to libvirt-lxc
  8. Glossary
  9. A Virtual Machine Drivers
  10. B Appendix
  11. C XM, XL Toolstacks and Libvirt framework
  12. D Documentation Updates
  13. E GNU Licenses
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SUSE Linux Enterprise Server Documentation › Virtualization Guide › Managing Virtual Machines with libvirt › Overview
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Applies to SUSE Linux Enterprise Server 12

8 Overview

libvirt is a library that provides a common API for managing popular virtualization solutions, among them KVM, LXC, and Xen. The library provides a normalized management API for these virtualization solutions, allowing a stable, cross-hypervisor interface for higher-level management tools. The library also provides APIs for management of virtual networks and storage on the VM Host Server. The configuration of each VM Guest is stored in an XML file.

With libvirt you can also manage your VM Guests remotely. It supports TLS encryption and x509 certificates as well as authentication with SASL.

The communication between the virtualization solutions (KVM, Xen, LXC) and the libvirt API is managed by the daemon libvirtd, which needs to run on the VM Host Server. libvirt client applications such as virt-manager, possibly running on a remote machine, communicate with libvirtd running on the VM Host Server, which services the requestusing native hypervisor APIs. Use the following commands to start and stop libvirtd or check its status: 

# systemctl start libvirtd.service 

# systemctl status libvirtd.service
libvirtd.service - Virtualization daemon
Loaded: loaded (/usr/lib/systemd/system/libvirtd.service; enabled)
Active: active (running) since Mon 2014-05-12 08:49:40 EDT; 2s ago
[...]

# systemctl stop libvirtd.service

# systemctl status libvirtd.service
[...]
Active: inactive (dead) since Mon 2014-05-12 08:51:11 EDT; 4s ago
[...]

To automatically start libvirtd at boot time, either activate it using the YaST Services Manager module or by entering the following command: 

systemctl enable libvirtd.service

The following libvirt-based tools are available on SUSE Linux Enterprise Server. They do not need to be run on the VM Host Server, allowing management of VM Host Servers and VM Guests via remote connections. This enables managing VM Host Servers centrally from a single workstation, alleviating the need to access each VM Host Server individually.

Virtual Machine Manager (virt-manager)

The Virtual Machine Manager is a desktop tool for managing VM Guests. It provides the ability to control the life cycle of existing machines (start/shutdown, pause/resume, save/restore) and create new VM Guests. It allows managing various types of storage and virtual networks. It provides access the graphical console of VM Guests with a built-in VNC viewer and can be used to view performance statistics. virt-manager supports connecting to a local libvirtd, managing a local VM Host Server, or a remote libvirtd managing a remote VM Host Server.

To start the Virtual Machine Manager, enter virt-manager at the command prompt.

virt-viewer

A viewer for the graphical console of a VM Guest. It uses SPICE (configured by default on the VM Guest) or VNC protocols and supports TLS and x509 certificates. VM Guests can be accessed by name, ID, or UUID. If the guest is not already running, the viewer can be told to wait until the guest starts, before attempting to connect to the console. virt-viewer is not installed by default and is available after installing the package virt-viewer.

virt-install

A command line tool for creating new VM Guests using the libvirt library. It supports graphical installations via VNC or SPICE protocols. Given suitable command line arguments, virt-install can run completely unattended. This allows for easy automation of guest installs. virt-install is the default installation tool used by the Virtual Machine Manager.

vm-install

A tool to set up a VM Guest, configure its devices and start the operating system installation. Starts a GUI wizard when called from a graphical user interface. When invoked on a terminal, starts the wizard in command-line mode. vm-install can be selected as the installation tool when creating a new virtual machine in the Virtual Machine Manager.

virsh

A command line tool to manage VM Guests with similar functionality as the Virtual Machine Manager. Allows you to change a VM Guest's status (start, stop, pause, etc.) to set up new guests and devices and to edit existing configurations. virsh is also useful to script VM Guest management operations.

virsh works like Subversion's svn command or zypper: it takes the first arguments as a command and further arguments as options to this command: 

virsh [-c URI] commanddomain-id [OPTIONS]

Just like zypper, virsh can also be called without a command. In this case it starts a shell waiting for your commands. This mode is useful when having to run subsequent commands: 

~> virsh -c qemu+ssh://wilber@mercury.example.com/system
Enter passphrase for key '/home/wilber/.ssh/id_rsa': 
Welcome to virsh, the virtualization interactive terminal.

Type:  'help' for help with commands
       'quit' to quit

virsh # hostname
mercury.example.com
→Chapter 9 Guest Installation←Part II Managing Virtual Machines with libvirt
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