Guide to particulars in customizing Ubuntu Installer

Question

I've tried reading through guides for preseeding and customization, but I did not understand how and where to modify which options. I can only comfortably learn through practical examples, for which I ask this question.

I am looking into preseeding and customizing solution to just do a few specific tasks:

• Completely rewrite the packages installed by default, much like minimal installs and with the --no-install-recommends flag of apt-get.
• Add a few proprietary applications to the default install list
• Automatically install and mount proprietary drivers on install and live session
• Edit the default configuration files for applications installed by default
• Specify partitions along with permission
• Modify the package pool in the installer media (CD/DVD/USB), preferably using command line tools similar to apt-get and aptitude.

Can anyone please tell me how to configure preseed option to only do the above?

NB I do not understand the GPG part after adding/removing packages in the pool.

PS The third point is of particular importance.

Answer 1

For a reference preseed, you might like to refer to installation-guide-i386 which contains the following sample preseed:

  /usr/share/doc/installation-guide-i386/example-preseed.txt.gz

• Completely rewrite the packages installed by default, much like minimal installs
• Add a few proprietary applications to the default install list

To provide the list of packages you want installed, you might like to look for the following line:

  tasksel tasksel/first   multiselect ubuntu-desktop

Where "ubuntu-desktop" can be changed for an arbitrary number of packages or meta packages.

• Automatically install and mount proprietary drivers on install and live session

Other that specifying the packages needed (for the proprietary drivers), I'm not sure how this would be accomplished. As a side note, you "mount" a partition, you "load" a kernel module/driver.

• Edit the default configuration files for applications installed by default

To make those kind of scripted changes, you probably want to look into:

  d-i preseed/late_command string ...

Where the "..." can be replaced with arbitrary commands like sed -i for example.

• Specify partitions along with permission

There's a partition section in the example preseed mentioned above.

Ubiquity with preseed

Casper supports preseed and ubiquity can have many values preseeded. Here are some of the variables that can be preseeded relevant to ubiquity:

ubiquity countrychooser/shortlist select US
ubiquity languagechooser/language-name select English
ubiquity localechooser/supported-locales multiselect en_US.UTF-8
ubiquity ubiquity/summary note
ubiquity ubiquity/reboot boolean true
ubiquity ubiquity/poweroff boolean true
ubiquity ubiquity/success_command string ...

Where "..." would contain the same as the late_command mentioned above, success_command is read by ubiquity and late_command by d-i.

Answer 2

The following creates a modified boot image. Burn it to a CD, or insert the ISO into a VM to test it. You'll need cpio and genisoimage (that's the names of the packages and executables).

The following is in the form of a Makefile, but can be entered interactively. ${IN_ISO} refers to the original ISO image (I used the -alternative version, and I'd suggest you do the same), ${OUT_ISO} to the desired ISO name.

# Extract the ISO image to mount/ and copy it to cdroot/
cdroot:
    mkdir -p mount
    sudo mount -o loop ${IN_ISO} mount
    mkdir cdroot
    cd cdroot && tar cf - ../mount --transform 's,^mount/,,' | tar xf -
    sudo umount mount && rm -r mount
    chmod -R a+rw cdroot

# Copy new files to the disk. Content of those files is posted below
prepare: cdroot
    cp isolinux.cfg cdroot/isolinux/isolinux.cfg
    test -e ./initrd.orig.gz || cp cdroot/install/initrd.gz ./initrd.orig.gz
    mkdir -p initrd
    cd initrd && gunzip <../initrd.orig.gz | sudo cpio -i && cd ..
    cp preseed.cfg initrd/preseed.cfg
    cd initrd && find . | cpio -o --format=newc | gzip -9 > ../cdroot/install/initrd.gz && cd ..
    sudo rm -rf initrd

# Create the ISO image. Make sure to use extensions for lower-case filenames    
iso: cdroot prepare
    genisoimage -o ${OUT_ISO} \
        -force-rr -J \
        -b isolinux/isolinux.bin -c isolinux/boot.cat \
        -no-emul-boot -boot-load-size 4 -boot-info-table \
        cdroot

You need some additional files:

isolinux.cfg configures the boot loader. You want it to just boot, and automatically go through the installation process. It should look like this:

default install
label install
  menu label ^Install my custom Ubuntu
  kernel /install/vmlinuz
  append auto initrd=/install/initrd.gz --
# Leave 2 seconds to abort or debug
prompt 1
timeout 20

That's all the preparations we need before actually configuring the installation. Download the preseed example and name it preseed.cfg. Go through it and edit whatever you want. Important options are:

# Locale
d-i debian-installer/locale string en_US
d-i time/zone string US/Eastern

# Partitioning. The following settings WILL OVERWRITE ANYTHING
# Don't insert the CD into your boss' computer ...
d-i partman-auto/method string regular
d-i partman/confirm_write_new_label boolean true
d-i partman/choose_partition select finish
d-i partman/confirm boolean true
d-i partman/confirm_nooverwrite boolean true

# To create a normal user account.
d-i passwd/user-fullname string Ubuntu User
d-i passwd/username string ubuntu
d-i passwd/user-password password insecure
d-i passwd/user-password-again password insecure
d-i user-setup/allow-password-weak boolean true

# Package selection. Don't include ubuntu-desktop to significantly reduce the content
tasksel tasksel/first multiselect standard

#d-i preseed/early_command string driver installation commands (stuff needed to boot)
#d-i preseed/late_command string driver installation commands, custom software, etc.

But I'd suggest you don't use the above as an example, but download Ubuntu's example and configure it to your needs with late_command, you can do anything from shell, including downloading and executing a script that installs and configures your custom software. For example, use this as late_command:

d-i preseed/late_command string in-target sh -c 'wget https://example.com/my/install.sh && sh install.sh'

Alternatively, you can place install.sh in the initrd above and execute it directly. Its content could look like this:

#!/bin/sh
aptitude install -y x11-apps any-package-you-want-installed
wget http://proprietary.com/drivers/for/ubuntu.tar.gz -O- | tar xf - && sh drivers/instal.sh

It really depends on how your proprietary driver installation routine works.