Using Kickstart to Automate CentOS VM Creation

I’ve done this using CentOS, but I’m pretty sure the same thing will work with RedHat the exact same way.

Virtualization is now a commodity with several free tools available from Sun, VMWare and Xen. If you’re like me, you like to create a new, clean VM for each experiment. However, this comes with a drawback - the installation process, choosing your timezone, putting in the same password every time, etc… takes a while.

Screen shot 2009-10-24 at 1.03.24 PM.png

Fortunately, CentOS provides the means to automate the process via a kickstart file. The best part is, after you do an install, you’ll have a kickstart file to start working with - it’ll save all your options in /root/anaconda-ks.cfg. You can edit this file later to include other packages that you’d like to install, such as the GCC c++ libraries. You can also run other commands through yum, and customize the system-wide bashrc.

I’m only going to go over how I did the install - for the full details check out the CentOS kickstart guide

I’ve created a minimal kickstart file to do a base install without gnome, printing, and any tools I don’t find useful. I’ve disabled X completely - I have no need to boot to a GUI. I’ve also uncommented the lines to configure the drive settings, so I won’t be prompted for anything along the way; my VM should be completely ready to go once I reboot after the installation. Pretty awesome.

There’s a convenient way to run a kickstart file off a http connection, so I’ve put it the web server on my dev box. My dev box’s IP address is, and I copied the modified /root/anaconda-ds.cnf (which I’ve renamed to ks.cfg) to the server. At the installation boot prompt, I’d enter:

linux ks=

Then let it run. After a bit it’ll ready to reboot and be used. Just make sure to unmount the install DVD.

Obviously this has a lot more uses than just creating VMs, but I’m not a sysadmin, so I haven’t personally used it outside the desktop environment. There’s other tools for different distros, and third party tools for CentOS/RedHat.

For what I’ve done so far, one could argue it’s easier just to create an image of the VM and to just clone that whenever I want a new one. That’s a good solution if I was interested in always creating the same exact VM. However, using the kickstart method has several advantages. I could create a simple web app that generates new configs based on what I’ve checked off in a few lists, allowing me to quickly fire up new VMs with the right software for whatever I’m working on. I can also upgrade the version of the OS and run the same kickstart, so I don’t have to maintain some up to date starting image.

If I’ve made any mistakes, please don’t hesitate to point them out. I’m by no means a guru on the subject, I’ve just wanted to look into this topic for a while.

Some Other Useful resources