* About This Document
* Ubuntu Server Guide
o Introduction
o Installation
o Package Management
o Networking
o Remote Administration
o Network Authentication
o Domain Name Service (DNS)
o Security
o Web Servers
o Databases
o LAMP Applications
o File Servers
o Email Services
o Version Control System
o Windows Networking
o Backups
o Virtualization
+ libvirt
+ JeOS and vmbuilder
+ Eucalyptus
+ OpenNebula
o Clustering
o Other Useful Applications
libvirt
* Ubuntu Server Guide
* Virtualization
The libvirt library is used to interface with different
virtualization technologies.
Before getting started with libvirt it is best to make sure your hardware supports the necessary
virtualization extensions for KVM. Enter the following from a terminal prompt:
egrep '(vmx|svm)' /proc/cpuinfo
If nothing is printed, it means that your cpu does not support hardware virtualization.
On most computer whose processor supports virtualization, it is
necessary to activate an option in the bios to enable it. The method
described above does not show the status of it's activation.
* 17.1.1. Virtual Networking
* 17.1.2. Installation
* 17.1.3. virt-install
* 17.1.4. virt-clone
* 17.1.5. Virtual Machine Management
* 17.1.6. Virtual Machine Viewer
* 17.1.7. Resources
17.1.1. Virtual Networking
There are a few different ways to allow a virtual machine access to the external network. The default virtual network configuration is
usermode networking, which uses the SLIRP protocol and traffic is NATed through the host interface to the outside network.
To enable external hosts to directly access services on virtual machines a bridge needs to be configured. This allows
the virtual interfaces to connect to the outside network through the physical interface, making them appear as normal hosts to the rest
of the network. For information on setting up a bridge see Section 4.1.4 ― Bridging.
17.1.2. Installation
To install the necessary packages, from a terminal prompt enter:
sudo apt-get install kvm libvirt-bin
After installing libvirt-bin, the user used to manage virtual machines will need to be added to
the libvirtd group. Doing so will grant the user access to the advanced networking options.
In a terminal enter:
sudo adduser $USER libvirtd
If the user chosen is the current user, you will need to log out and back in for the new group membership to take effect.
You are now ready to install a Guest operating system. Installing a virtual machine follows the same
process as installing the operating system directly on the hardware. You either need a way to automate the installation, or
a keyboard and monitor will need to be attached to the physical machine.
In the case of virtual machines a Graphical User Interface (GUI) is analogous to using a physical keyboard and mouse. Instead of installing
a GUI the virt-viewer application can be used to connect to a virtual machine's console using VNC.
See Section 17.1.6 ― Virtual Machine Viewer for more information.
There are several ways to automate the Ubuntu installation process, for example using
preseeds, kickstart, etc. Refer to the Ubuntu Installation Guide for details.
Yet another way to install an Ubuntu virtual machine is to use ubuntu-vm-builder. ubuntu-vm-builder
allows you to setup advanced partitions, execute custom post-install scripts, etc. For details see Section 17.2 ― JeOS and vmbuilder
17.1.3. virt-install
virt-install is part of the python-virtinst package. To install it, from a terminal prompt enter:
sudo apt-get install python-virtinst
There are several options available when using virt-install. For example:
sudo virt-install -n web_devel -r 256 -f web_devel.img \
-s 4 -c jeos.iso –accelerate \
–connect=qemu:///system –vnc \
–noautoconsole -v
*
-n web_devel: the name of the new virtual machine will be web_devel in this example.
*
-r 256: specifies the amount of memory the virtual machine will use.
*
-f web_devel.img: indicates the path to the virtual disk which can be a file, partition, or logical volume.
In this example a file named web_devel.img.
*
-s 4: the size of the virtual disk.
*
-c jeos.iso: file to be used as a virtual CDROM. The file can be either an ISO file or the path to the
host's CDROM device.
*
–accelerate: enables the kernel's acceleration technologies.
*
–vnc: exports the guest's virtual console using VNC.
*
–noautoconsole: will not automatically connect to the virtual machine's console.
*
-v: creates a fully virtualized guest.
After launching virt-install you can connect to the virtual machine's console either locally
using a GUI or with the virt-viewer utility.
17.1.4. virt-clone
The virt-clone application can be used to copy one virtual machine to another. For example:
sudo virt-clone -o web_devel -n database_devel -f /path/to/database_devel.img –connect=qemu:///system
*
-o: original virtual machine.
*
-n: name of the new virtual machine.
*
-f: path to the file, logical volume, or partition to be used by the new virtual machine.
*
–connect: specifies which hypervisor to connect to.
Also, use -d or –debug option to help troubleshoot problems with
virt-clone.
Replace web_devel and database_devel with appropriate virtual machine names.
17.1.5. Virtual Machine Management
* 17.1.5.1. virsh
* 17.1.5.2. Virtual Machine Manager
17.1.5.1. virsh
There are several utilities available to manage virtual machines and libvirt.
The virsh utility can be used from the command line. Some examples:
*
To list running virtual machines:
virsh -c qemu:///system list
*
To start a virtual machine:
virsh -c qemu:///system start web_devel
*
Similarly, to start a virtual machine at boot:
virsh -c qemu:///system autostart web_devel
*
Reboot a virtual machine with:
virsh -c qemu:///system reboot web_devel
*
The state of virtual machines can be saved to a file in order to be restored later. The
following will save the virtual machine state into a file named according to the date:
virsh -c qemu:///system save web_devel web_devel-022708.state
Once saved the virtual machine will no longer be running.
*
A saved virtual machine can be restored using:
virsh -c qemu:///system restore web_devel-022708.state
*
To shutdown a virtual machine do:
virsh -c qemu:///system shutdown web_devel
*
A CDROM device can be mounted in a virtual machine by entering:
virsh -c qemu:///system attach-disk web_devel /dev/cdrom /media/cdrom
In the above examples replace web_devel with the appropriate virtual machine name, and
web_devel-022708.state with a descriptive file name.
17.1.5.2. Virtual Machine Manager
The virt-manager package contains a graphical utility to manage local and remote virtual machines.
To install virt-manager enter:
sudo apt-get install virt-manager
Since virt-manager requires a Graphical User Interface (GUI) environment it is recommended to be
installed on a workstation or test machine instead of a production server. To connect to the local
libvirt service enter:
virt-manager -c qemu:///system
You can connect to the libvirt service running on another host by entering the following in a terminal prompt:
virt-manager -c qemu+ssh://virtnode1.mydomain.com/system
The above example assumes that SSH connectivity between the management system and virtnode1.mydomain.com
has already been configured, and uses SSH keys for authentication. SSH keys are needed because
libvirt sends the password prompt to another process. For details on configuring
SSH see Section 5.1 ― OpenSSH Server
17.1.6. Virtual Machine Viewer
The virt-viewer application allows you to connect to a virtual machine's console.
virt-viewer does require a Graphical User Interface (GUI) to interface with the virtual machine.
To install virt-viewer from a terminal enter:
sudo apt-get install virt-viewer
Once a virtual machine is installed and running you can connect to the virtual machine's console by using:
virt-viewer -c qemu:///system web_devel
Similar to virt-manager, virt-viewer can connect to a remote host using
SSH with key authentication, as well:
virt-viewer -c qemu+ssh://virtnode1.mydomain.com/system web_devel
Be sure to replace web_devel with the appropriate virtual machine name.
If configured to use a bridged network interface you can also setup SSH access
to the virtual machine. See Section 5.1 ― OpenSSH Server and Section 4.1.4 ― Bridging for more details.
17.1.7. Resources
*
See the KVM home page for more details.
*
For more information on libvirt see the libvirt home page
*
The Virtual Machine Manager site has more information on
virt-manager development.
*
Also, stop by the #ubuntu-virt IRC channel on freenode to
discuss virtualization technology in Ubuntu.
libvirt JeOS and vmbuilder