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UDIB

UDIB is the Unattended Debian Installation Builder. It provides a handy commandline utility for injecting files into Debian installation ISOs. Using UDIB, you can preseed an ISO by injecting a preseed file. Preseeded ISOs allow fully automated Debian installations on bare metal (or anywhere else).

Quick Start Guide

This short guide explains how to build a Debian ISO with a customized and automated installation:

  1. make sure you have all the required software installed
  2. clone this repo and cd into your local copy
  3. (optional) create and activate a virtual environment: python3 -m venv .venv && . .venv/bin/activate
  4. install the required python packages: pip install -r requirements.txt
  5. all the Debian ISOs are available in https://cdimage.debian.org/mirror/cdimage/archive/
  6. create the custom ISOs: ./udib.py inject -i debian-11.10.0-amd64-netinst.iso
  7. boot from the -modified.iso on your target machine (or in a VM)

Depending on how many answers you provided in the preseed file, the installation may require some manual interaction. Preseed files are very powerful, and if you need more customization you can have a deeper look into how they work. You can also use UDIB to get the full preseed example file: ./udib.py get preseed-file-full and use that as a starting point. Be sure to have a look at the usage reference for a closer look at UDIB itself.

What's preseeding?

A preseed file is a text file which provides the Debian installer with previously set (preseeded) answers during the installation process. Preseeding a Debian ISO allows you to heavily reduce the amount of user interaction required during an installation, or even fully automate it. The preseed file is written by you and then injected into the installation image. When you start the installation, any answers you have provided to the debian installer as part of your preseed file are automatically applied during the installation. If you want to know more, you can have a look at Debian's official guide or at the Debian wiki's quick overview, both of which explain preseeding much better than I can.

How does UDIB work?

UDIB's main purpose is the injection files into existing Debian installation ISOs. In a nutshell, it does this by extracting the ISO, adding the files to the ISO's initrd, and repacking the ISO again. You could do all of this manually of course by following the basic and advanced guides for ISO repacking on the Debian wiki, but UDIB does all of this for you.

Dependencies

Using UDIB to create ISOs requires the following software:

  • GNU/Linux
  • python3 (3.10.4 known to work)
  • xorriso (1.5.4 known to work)
  • GNU gpg
    • preinstalled on most distributions
  • GNU cpio
    • preinstalled on most distributions
  • GNU sha512sum
    • preinstalled on most distributions

Internet access is (obviously) required if you want to fetch any files using UDIB.

Detailed usage guide

You can view help at the commandline using ./udib.py --help for general options and ./udib.py COMMAND --help for help with a specific subcommand.

The name and destination of files produced by udib.py can be specified with the --output-file option. Alternatively, you can use the --output-dir option to specify the directory where produced files will be saved, without having to name them explicitly (default names will be used).

Retrieving example preseed files or vanilla ISOs

As a starting point for creating your own preseeded ISO, you can retrieve one of Debian's example preseed files or an unmodified Debian ISO using UDIB:

udib.py [--output-file FILE | --output-dir DIR] get WHAT

WHAT must be a specific string and can be either one of:

  • preseed-file-basic to download Debian's basic example preseed file (sufficient in most cases)
  • preseed-file-full to download Debian's full example preseed file (has a LOT of customization options)
  • iso to download the latest, unmodified Debian stable x86-64 netinst ISO

Injecting files into an ISO

To inject existing files into an ISO, you can run the following command:

udib.py [--output-file FILE | --output-dir DIR] inject [--image-file IMAGEFILE] FILE [FILE ...]

where FILE is the path to the file you want to inject. Injected files are added at the root of the installer's filesystem and can be accessed there during the installation. NOTE: the installer will not recognize a preseed file unless it's filename is preseed.cfg exactly. If you don't specify an --image-file, UDIB will download the latest Debian x86-64 netinst ISO and inject your FILEs into it.