Remastering a Ubuntu Alternate CD

From COMPSA

Warning! If you are not familiar with at least the basics of Linux or virtual machines it is suggested that you get some time using them before attempting to follow the instructions on this page.

Overview

The goal of this page is to outline the process that we've come down to for creating an install CD for Ubuntu which is faster and easier to run on a large number of systems than the regular install is. This custom CD is also supposed to have all updates streamed into it (or at least a mechanism in place to automatically perform these updates) and should install common software not included in Ubuntu's default installation (such as the Flash player, MP3 support, etc.).

Useful tools

VMWare server is helpful for testing installations in a quick fashion (and can test remastered CDs without requiring you to use up physical media). VMWare is available at no cost from VMWare.com (you'll need a serial number from the same site, feel free to use mailinator or whatever instead of your real info if you'd like; they are a well-behaved company, though, in terms of sending out e-mail).

QEmu is a also available; it can perform the same function as VMWare server; but, also allows people on other architectures to make their machine emulate an x86 processor. QEmu website

You will require a Linux distribution to be able to remaster CDs. Just about any modern distribution is fine as the tools we use are pretty much universal (mount, rsync, a text editor, and mkisofs). The remastering process requires a significant amount of hard drive space (I'd suggest plan for it to use at least 10 GB assuming you use one or more virtual machines for testing your CD).

The Process

1) Fetch a copy of Ubuntu's alternate install CD if you don't have one already. Do not get the Live CD (which is the default one). Unless you know otherwise you want to get the i386 version (since that's what all of the machines we've been donated so far require).

2) Extract the files from the ISO image to a directory, let's call it buntu (note: you can't use a graphical tool like Archive Manager to do this-- it'll appear to succeed; but, will create a corrupt CD later on-- you must perform this command as root)

mount ubuntu-6.06.1-alternate-i386.iso ubuntu-iso/ -t iso9660,ro -o loop
rsync -azvb --delete ubuntu-iso/ buntu/

3) Change into directory buntu

4) Add to isolinux/isolinux.cfg directly before the LABEL install bit this (everything after append should be on the same line):

LABEL forcause
 menu label Install Co^mputers for a Cause version
 kernel /install/vmlinuz
 append  debian-installer/locale=en_US kbd-chooser/method=us
netcfg/get_hostname=ubuntu debconf/priority=critical
preseed/file/cdrom/preseed/cause.seed
initrd=/install/initrd.gz ramdisk_size=16384 root=/dev/ram rw --

(this adds a new option to the menu when the install CD starts up titled Install Computers for a Cause version and specifies language and location information. It also tells the installer where to look for information about what installation options to pick and tells the installer not to ask about anything but critical decisions)

5) Copy the contents of cause.seed to a plain text file preseed/cause.seed

6) Optional If you'd like edit isolinux/splash.pcx to be a pretty custom startup screen.

7) Change back up a directory so you're in the directory above buntu

8) Generate a new CD image called NewCD.iso

mkisofs    \
-r    \
-V "Ubuntu 6.06.1 i386"    \
-cache-inodes    \
-J    \
-l    \
-b isolinux/isolinux.bin    \
-c isolinux/boot.cat    \
-no-emul-boot    \
-boot-load-size 4    \
-boot-info-table    \
-o ../NewCD.iso buntu/

9) Voila! You now have a customized Ubuntu CD. Feel free to test it in VMWare or QEmu or to burn it to a physical CD.

Cafehack Group

Monday, August 31, 2009