Build a Fedora Live CD

            In December 2006, the Fedora Linux distribution released its first official Live CD, which, thanks to an intelligent selection of applications, nicely advertises the best features of Fedora. In addition to many applications, the Live CD has several games, uses the Compiz 3D desktop, and is accessible by non-English speaking users. But what stole the show for me was David Zeuthen's livecd tools, which make creating and maintaining a custom Fedora-based Live CD a walk in the park.

Zeuthen is the developer of Pilgrim, which creates system images that can run off USB flash drives for the One Laptop Per Child project . The livecd tools used for creating the Fedora Live CD is a rewrite of Pilgrim in Python. It can be used for creating live CDs out of Red Hat Enterprise Linux, CentOS, and other downstream Fedora distributions.

                Before getting down to making your own Live CD, you need to understand how a Fedora release is assembled, distributed, and maintained. The Fedora project keeps packages in two publicly accessible repositories. The repository maintained by official Fedora developers is called the "core" repository, while the one maintained by contributors and the community is called the "extras" repository. A repository is simply a collection of packages. Apart from the core and extras, there are several third-party repositories such as Livna and FreshRPM.

                A Fedora Core distribution contains all the packages in the core repository, the latest being Fedora Core 6. The first official Fedora Live CD is based on packages in Fedora Core 6 and the extras repository. The livecd tools have been submitted for inclusion in Fedora's extras repository, which will be merged with the core repository by the time Fedora 7 is released.

What makes the  live cd tools special?

The biggest advantage of the livecd tools approach to creating Live CDs is the design that separates the tools from the Live CD. To cook a Live CD, all you need is a set of configuration files. These configuration files contain a list of packages that you need on the Live CD and also describe the type of system configuration that will happen once the Live CD is booted.

To assist the custom Live CD maintainer, these configuration files are packaged as RPMs and kept in a repository of their own. As the Fedora distribution and its repositories move from version to version, you can keep updating these configuration files to pull the relevant packages.

Zeuthen has made available three such RPMs that you can base your custom Live CDs on. These RPMs follow an inheritance scheme that assists in creating derivative versions. The fedora-livecd package is a minimal Live CD with no user interface. The fedora-livecd-gnome package is based on the fedora-base package and includes a GNOME desktop. The fedora-livecd-desktop packages builds on top of the fedora-gnome package and gives a GNOME desktop with lots of applications and other things.

Figure 1, from Zeuthen, explains this better.

Zeuthen also suggests that in the future it might also help other official Fedora Special Interest Groups (SIGs) to roll their own distributions derived from these RPMs.