KVM Tutorial

Installing KVM

Check if your CPU supports hardware virtualization via command:

egrep '(vmx|svm)' --color=always /proc/cpuinfo

If nothing is displayed CPU doesn't support virtualization.

Instal packages ubuntu-virt-server, python-vm-builder and kvm-pxe via command (but just in case, first update the package repository on the node):

apt-get update
apt-get install ubuntu-virt-server python-vm-builder kvm-pxe

Add the current user to the group:

adduser `id -un` libvirtd
adduser `id -un` kvm

Logout and login again:

logout
ssh root@node1-1

Check users group by comamand:

groups

Output should be similar to:

root kvm libvirtd

To list all running KVMs use:

virsh -c qemu:///system list

Setup network bridge on the host

Install the package bridge-utils:

apt-get install bridge-utils

Create the bridge interface named br0:

brctl addbr br0

Edit the network interfaces configuration with editor (for example nano):

nano /etc/network/interfaces

and add persistent configuration for br0 interface:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth1
iface eth1 inet dhcp

# The secondary network interface
auto eth0
iface eth0 inet manual

#Bridge 0 interface
auto br0
iface br0 inet static
  address 10.28.1.1
  netmask 255.255.0.0
  broadcast 10.28.255.255
  network 10.28.0.0
  bridge_ports eth0
  bridge_fd 9
  bridge_hello 2
  bridge_maxage 12
  bridge_stp off

Restart networking with command:

/etc/init.d/networking restart

For bridge verification open the new ssh window and run:

tcpdump -i br0

and then, in the other window, try to ping some adress in same subnet, for example:

ping 10.28.0.1

In the second windows you should see logging ofrequest/reply messages.

It is recommended to reboot the machine once the bridge is configured.

Create and run KVM image using vmbuilder

Folder /var/lib/libvirt/images/ will be created for storing images. Each image will have separate folder for example /var/lib/libvirt/images/virtual-machine1

Create necessary folders:

mkdir -p /var/lib/libvirt/images/vm1/mytemplates/libvirt

'-p' option of mkdir command means that all parent folders will be created if they do not exist.

vmbuilder tool uses templates for creating of images so copy the template:

cp /etc/vmbuilder/libvirt/* /var/lib/libvirt/images/vm1/mytemplates/libvirt/

Open partition configuration file with command:

nano /var/lib/libvirt/images/vm1/vmbuilder.partition

and add the following lines:

root 8000
swap 4000
---
/var 20000

Copied text defines three partitions - root, swap and var and their sizes. "—-" means that var partition will be separate image file.

Go to folder vm1:

cd /var/lib/libvirt/images/vm1/

Execute vmbuilder command:

vmbuilder kvm ubuntu --suite=oneiric --flavour=virtual --arch=amd64 --mirror=http://de.archive.ubuntu.com/ubuntu -o --libvirt=qemu:///system --ip=10.28.4.4 --gw=10.28.0.1 --mask=255.255.0.0 --bcast=10.28.255.255 --net=10.28.0.0 --dns=10.0.0.9 --part=vmbuilder.partition --templates=mytemplates --user=guest --name=Guest --pass=guest --addpkg=vim-nox --addpkg=unattended-upgrades --addpkg=acpid --mem=256 --hostname=vm1 --bridge=br0 --addpkg openssh-server --addpkg nano

Create and run KVM image using KVM directly

Download ubuntu server ISO file:

wget -O ubuntu-server.iso http://www.ubuntu.com/start-download?distro=server&bits=64&release=latest 

Create Disk:

qemu-img create -f qcow2 vm-oneric-amd64-serial 10G

Setup network bridge (see part III).

Install tool for Tun:

apt-get install uml-utilities

Create the tap interface:

tunctl

Output of the name is (tap0).

Add tap interface to the bridge as a port:

brctl addif br0 tap0

Bring up tap0 interface:

ifconfig tap0 up

Boot and Install Ubuntu using VNC:

kvm -daemonize -m 1024 -hda vm-oneric-amd64-serial -cdrom ubuntu-server.iso -boot d -smp 2 -cpu qemu64 -net nic,model=virtio -net tap,ifname=tap0,script=no -vnc :0

To run already created image you can enter:

kvm -daemonize -m 1024 -hda vm-oneric-amd64-serial  -smp 2 -cpu qemu64 -net nic,model=virtio -net tap,ifname=tap0,script=no -vnc :0

Use VNC client to connect to virtual machine. Kill Virtual machine (KVM process):

pkill -9 kvm

Remove tap0 in as a bridge interface:

brctl delif br0 tap0

Delete tap interface:

tunctl -d tap0

kvm -daemonize -m 1024 -hda vm-oneric-amd64-serial -smp 2 -cpu qemu64 -net nic,model=virtio -net tap,ifname=tap0,script=no -vnc :0

kvm -daemonize -m 1024 -hda vm-oneric-amd64-serial -cdrom ubuntu-11.10-server-amd64.iso -boot d -smp 2 -cpu qemu64 -net nic,model=virtio -net tap,ifname=tap0,script=no -vnc :0