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 on 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!