Systemimager and KVM guests - tips

Recently I've been figuring out how to deploy kvm guests with systemimager and pxe. This is a continuation of my previous story.

If you go for kvm you will probably end up using virtio network and virtio-hdd drivers with your guests as they provide best performance. Using these drivers implies some strange hdd naming. You place your instalation od /dev/vda instead of /dev/sda. Unfortunately systemimager (or better - systeminstaller - one of its components), will not recognize vda disks properly which leads to some complications.

Normally, when you run si_prepareclient on your golden-client, partitioning configuration is placed in file /etc/systemimager/autoinstallscript.conf in section <config><disk> (this is done by systeminstaller in fact). Then this section is used by si_mkautoinstallscript to generate parted commands in your <imagename>.master script. In case of /dev/vda disk, the <config><disk> section is empty, therefore you don't get the partitioning section in .master script. Due to this, deployment of your kvm guest image will fail as no partitions will be created. You may either want to debug systeminstaler (try do tebug perl code ;-) or just work it around, which is what I chose.

What you need to do
First, manually add the <disk> section on the golden client to /etc/systemimager/autoinstallscript.conf after you run si_prepareclient. The file might now be looking like this. The <disk> section is in italics.

This one is taken from redhat with no LVM, the hdd size is 12gb, and 2gb go for swap:
<config>
<disk dev="/dev/vda" label_type="msdos" unit_of_measurement="MB">
<!--
This disk's output was brought to you by the partition tool "parted",
and by the numbers 4 and 5 and the letter Q.
-->
<part num="1" size="101" p_type="primary" p_name="-" flags="boot" />
<part num="2" size="10676" p_type="primary" p_name="-" flags="-" />
<part num="3" size="2097" p_type="primary" p_name="-" flags="-" />
</disk>

<fsinfo line="10" real_dev="/dev/vda2" mount_dev="LABEL=/" mp="/" fs="ext3" options="defaults" dump="1" pass="1" />
<fsinfo line="20" real_dev="/dev/vda1" mount_dev="LABEL=/boot" mp="/boot" fs="ext3" options="defaults" dump="1" pass="2" />
<fsinfo line="30" real_dev="tmpfs" mp="/dev/shm" fs="tmpfs" options="defaults" dump="0" pass="0" />
<fsinfo line="40" real_dev="devpts" mp="/dev/pts" fs="devpts" options="gid=5,mode=620" dump="0" pass="0" />
<fsinfo line="50" real_dev="sysfs" mp="/sys" fs="sysfs" options="defaults" dump="0" pass="0" />
<fsinfo line="60" real_dev="proc" mp="/proc" fs="proc" options="defaults" dump="0" pass="0" />
<fsinfo line="70" real_dev="/dev/vda3" mount_dev="LABEL=SWAP-vda3" mp="swap" fs="swap" options="defaults" dump="0" pass="0" />

<boel devstyle="udev"/>

</config>

Second: pull the image from the golden-client (si_getimage).

Third: check your /var/lib/systemimager/scripts/<imagename>.master if it contains "parted" section (cat <imagename>.master |grep parted or something like this should verify this).

Fourth: have your image deployed to a new vm:
si_mkclientnetboot --image yourimage --flavor yourimage
The --flavor is needed to use a kernel with virtio drivers for deployment - it needs to recognize your /dev/vda and virtio ethernet.

That's all. Reboot your new vm with pxe boot and watch your image being deployed.
Comments welcome ;-)