Sunday, June 29, 2014

Replicating Fedora Machines using Kickstart

Sometimes one wants to install more machines the same as one that is already working.  Replication is one point where Linux is light years ahead of the competition.

Using Kickstart, you can roll out thousands of identically configured machines (with hardware that may be completely different) in a jiffy - Kickstart will automatically install the correct device drivers.

The Skinny

I usually do it manually, since it is too simple to bother scripting:
  • Save file /root/anaconda-ks.cfg
  • Save /etc/yum.repos.d with tar -zcvf yum.repos.d.tgz /etc/yum.repos.d
  • Save the packages list with yum list installed > packages
Use the saved kickstart file to install the new machine, untar the repos and run yum -y install $(cat packages) or yum -y install < packages

Booting Kickstart

Kickstart is the remote control system of the Red Hat Anaconda installer.

A Kickstart installation requires access to the Linux installation media on a local CD-ROM drive or hard drive, or over the network using HTTP or NFS.

If you need just one or two new machines, then do it manually.  If you need hundreds or thousands, then it is worth modifying the Kickstart file to make installation completely hands free.

To use a Kickstart file to install a system:
  1. Boot the system from a Live CD or USB schtick. If you need to modify the boot command, press Esc to access the command line.
  2. If you have not customized the boot medium to use Kickstart, use the ks option to specify the location of the Kickstart file.

    For example, the following boot command specifies that the Kickstart file is on the boot CD:
    boot: linux ks=cdrom:/ks.cfg
    If the Kickstart file is located on an NFS server, you might use a boot command such as the following:
    boot: linux ksdevice=em1 ip=dhcp ks=nfs:192.168.1.100:/ksfiles/ks.cfg
    where ksdevice=em1 specifies the network interface and ip=dhcp specifies that DHCP should be used to configure this interface.
That is all there is to Kickstart - it works.

Synchronizing Two Machines

If you have two existing machines and you want to ensure that they have the same packages installed, then you can use dnf or yum:

Get the list of installed packages one one machine (sort just makes it nice):
$ rpm -qa --qf "%{name}.%{arch}\n" | sort > packages.lst
 
Install missing packages from the list on the other machine:
$ sudo dnf install $(cat packages.lst)

Do it both ways and they will end up the exact same.


La Voila!

    2 comments:

    1. Hi Herman,
      I'm here cuz you mentioned that kickstart was a way to save a particular build of linux to install easily later on. I'm stuck at the "Boot the system from a USB schtick". I've got a live USB and when I get to the boot screen I have the options: Start Fedora, Test this media and Start Fedora, Troubleshooting >. If I press e to edit an option it seems the boot: command is not recognized. I'm sure I'm missing something simple here. Any thoughts?

      ReplyDelete
    2. That is the most difficult part. It could require a bit of faffing around till you figure out exactly when to press the esc key unfortunately!

      https://docs.fedoraproject.org/en-US/Fedora/20/html/Installation_Guide/ap-admin-options.html

      https://docs.fedoraproject.org/en-US/Fedora/20/html/Installation_Guide/s1-kickstart2-startinginstall.html

      ReplyDelete

    On topic comments are welcome. Junk will be deleted.