Virtualization in Grid'5000
Purpose
This page presents how to use KVM on the production environment, with a "non-deploy" reservation. The aim is to permit the execution of virtual machines on the nodes, along with a subnet reservation, which will give you a range of routed IP for your experiment.
Note | |
---|---|
For more network related information, see the virtual network interlink page. |
In the second part, we will explain more precisely the contextualization mechanism, which allow you to customize your virtual machines.
Quick start
In this part, we will create a virtual machine in a few steps, and ssh to it.
Job submission
In order to test easily the kvm environment, we use an interactive job, and we reserve one subnet and one node.
Disk image, virtual machine
A disk image containing debian squeeze is available at the following path:
/grid5000/images/KVM/squeeze-x64-base.qcow2
It can be used as a base for more advanced work. For the next steps of this tutorial, copy the disk image to /tmp on the node:
Network configuration
In order to use the network with kvm, a Tun/Tap interface must be created for each virtual machines. This virtual interface will be attached to your virtual machine, and bridged on the production network. Therefore, the virtual machine will be able to get an IP from the DHCP server and access the network.
A script is available to create automatically this interface on the node:
create_tap
:
- Tun/Tap interfaces are listed by issuing the command
/sbin/ifconfig
.
tap0 Link encap:Ethernet HWaddr 00:16:3e:db:c6:41 inet6 addr: fe80::58ff:a4ff:fe97:c6a8/64 Scope:Link UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:29435 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
Note | |
---|---|
- Create one Tun/Tap interface per guest OS. - Use |
Generate the contextualization iso file
This file contains a script which will set the network configration of your VM.
First, choose an IP in the range you have reserved. The command g5k-subnets
will give you more information.
10.172.0.0/22 10.175.255.255 255.252.0.0 10.175.255.254 10.172.0.0 dns.luxembourg.grid5000.fr 172.16.191.101
You can get the list of available IP, and an associated unique mac address with the following command.
10.172.0.1 00:16:3E:AC:00:01 10.172.0.2 00:16:3E:AC:00:02 10.172.0.3 00:16:3E:AC:00:03 10.172.0.4 00:16:3E:AC:00:04 10.172.0.5 00:16:3E:AC:00:05 10.172.0.6 00:16:3E:AC:00:06 10.172.0.7 00:16:3E:AC:00:07 10.172.0.8 00:16:3E:AC:00:08 10.172.0.9 00:16:3E:AC:00:09 10.172.0.10 00:16:3E:AC:00:0A ...
Generate this iso file with this command:
Run the guest OS using the kvm command
Start the virtual machine with the kvm command. The following command is just an example, feel free to adapt it to your use case.
The kvm process is launched in a screen
session, if you are not familiar with screen, read its documentation.
node :
|
screen kvm -m 512 -hda /tmp/squeeze-x64-base.qcow2 -cdrom $ISOFILE -net nic,model=virtio,macaddr=$MACADDR -net tap,ifname=tap0,script=no -nographic |
Or, use libvirt
Libvirt is a toolkit for managing virtualization servers. Libvirt is also an abstraction layer for different virtualization solutions, including KVM but also Xen and VMWare ESX. In our case, we use libvirt on top of KVM.
- Create a domain file in XML, describing a virtual machine. Don't forget to adapt this example to your case (especially, replace the mac address by a randomly generated one).
eg : domain.xml
<domain type='kvm'> <name>squeeze</name> <memory>524288</memory> <vcpu>1</vcpu> <os> <type arch="x86_64">hvm</type> </os> <clock sync="localtime"/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash> <devices> <emulator>/usr/bin/kvm</emulator> <disk type='file' device='disk'> <driver type='qcow2'/> <source file='/tmp/squeeze-x64-base.qcow2'/> <target dev='vda' bus='virtio'/> <shareable/> </disk> <disk type='file' device='cdrom'> <source file='/tmp/kvm-context.iso'/> <target dev='vdb' bus='virtio'/> <readonly/> </disk> <interface type='ethernet'> <target dev='tap0'/> <script path='no'/> <model type='virtio'/> <mac address='00:16:3e:ac:00:01'/> </interface> <serial type='pty'> <source path='/dev/ttyS0'/> <target port='0'/> </serial> <console type='pty'> <source path='/dev/ttyS0'/> <target port='0'/> </console> </devices> </domain>
- Now, the guest OS can be started.
- You can also use
virsh
to manage your guest OS:- list the running virtual machines:
virsh list
- open a console on the "squeeze" virtual machine:
virsh console squeeze
- list the running virtual machines:
KVM contextualization explained
This part describes the basic usage of a contextualization iso file with KVM, in order to configure the virtual machines (especially the network side). The contextualization script can be easily extended for other purposes.
Mechanism
Principe
Contextualization mechanism works like the following :
- Test for the presence of a CD in the CD drive of the VM
- if it exists, mount the CD, test the presence of a script
post-install
, and run it as root - if it does not exist, use
dhcp
on the first network interface.
Installation
The contextualization mechanism is not standard, if you want to use it on your vm, you must copy and adapt a few scripts.
- The contextualization script is executed during the boot sequence.
This script can be placed in /etc/rc.local
, at the end of the file (before the exit 0 if any).
# KVM contextualization script /usr/local/bin/init
- Here is an example of a contextualization script :
#!/bin/bash DEVICE= [ -b /dev/hdb ] && DEVICE=/dev/hdb [ -b /dev/sdb ] && DEVICE=/dev/sdb [ -b /dev/vdb ] && DEVICE=/dev/vdb [ -b /dev/xvdb ] && DEVICE=/dev/xvdb [ -b /dev/sr0 ] && DEVICE=/dev/sr0 if [ -b "$DEVICE" ];then /bin/mount -t iso9660 $DEVICE /mnt 2> /dev/null if [ -f /mnt/post-install ]; then bash /mnt/post-install fi umount /mnt 2> /dev/null else ifup eth0 fi exit 0
Generate your iso file for the contextualization
This part explain how to generate the contextualization iso file manually.
The manipulation can be automated with the script g5k-vm
.
- A basic example of contextualization iso file is available at
/grid5000/images/KVM/kvm-context.tgz
on each site.- the entry point is the file
kvm-context/post-install
; - this example configure the network interface using a static IP address and the network information provided in the file
kvm-context/network/common
; - you can customize that iso file for your experiments.
- the entry point is the file
- Use the tool
genisoimage
to generate the contextualization iso file.
Retrieve the file kvm-context.tgz
Uncompress the file /grid5000/images/KVM/kvm-context.tgz
in your home directory. This tarball contains an example of contextualization script.
Adapt the network configuration in the contextualization script
- The contextualization script will apply your network settings.
- The command
g5k-subnets
will give you all the needed network information related to your reservation.
- Choose an IP and a mac address in your range:
10.172.0.1 00:16:3E:AC:00:01 10.172.0.2 00:16:3E:AC:00:02 10.172.0.3 00:16:3E:AC:00:03 10.172.0.4 00:16:3E:AC:00:04 10.172.0.5 00:16:3E:AC:00:05 10.172.0.6 00:16:3E:AC:00:06 10.172.0.7 00:16:3E:AC:00:07 10.172.0.8 00:16:3E:AC:00:08 10.172.0.9 00:16:3E:AC:00:09 10.172.0.10 00:16:3E:AC:00:0A ...
- Following the information displayed, you should adapt the file
./kvm-context/common/network
.
This file is used by the script ./kvm-context/distributions/debian/00_network
in order to configure the network interface for your VM.
IPADDR=10.172.0.1 MACADDR=00:16:3e:ac:00:01 GATEWAY=10.175.255.254 NETWORK=10.172.0.0 BROADCAST=10.175.255.255 NETMASK=255.252.0.0 NAMESERVER=172.16.191.101 DOMAIN=luxembourg.grid5000.fr SEARCH=luxembourg.grid5000.fr
Generate the iso file
Once you have prepared the content of the iso file for the contextualization, you can generate it in /tmp
on the node.
The file (kvm-context-10.172.0.1.iso
) is ready to be attached to a VM, the script included in the iso will then configure the network interface during boot time.