Debian Trixie (13) Unattended Installer

A Docker-based solution for creating a customized Debian Trixie (Debian 13) unattended installation ISO.

Features

This automated installer includes:

• Language: English (en_US.UTF-8)
• Country: Switzerland (CH)
• Keyboard Layout: Swiss French (ch-fr)
• Partitioning: Automatic full disk partitioning
• Desktop Environment: None (server installation)
• Packages: Standard system utilities and SSH server
• SSH Configuration: PermitRootLogin enabled (set to yes)
• Additional Scripts: Support for custom post-installation scripts

Requirements

• Docker installed on your system
• Sufficient disk space (~2GB for building)
• Internet connection to download Debian ISO

Quick Start

1. Build the Docker Image

docker build -t debian-trixie-installer .

2. Create the Unattended ISO

Run the Docker container to build the custom ISO:

docker run --rm --privileged \
  -v $(pwd)/output:/output \
  debian-trixie-installer

The ISO will be created in the output/ directory as debian-trixie-unattended.iso.

3. Use the ISO

You can now use the generated ISO to:

• Boot from a USB drive (use tools like dd, Rufus, or Etcher to write to USB)
• Boot in a virtual machine (VirtualBox, VMware, QEMU, etc.)
• Deploy on physical hardware

The installation will start automatically after 1 second.

Default Credentials

⚠️ Warning: Change these default credentials for production use!

• Root password: root
• User: debian / Password: debian

Customization

Modify Preseed Configuration

Edit preseed.cfg to customize:

• Passwords (use mkpasswd -m sha-512 to generate encrypted passwords)
• Hostname and domain
• Package selection
• Partitioning scheme
• Time zone
• And more...

Add Custom Scripts

Place your custom post-installation scripts in the additional-scripts/ directory. These scripts will be copied to /root/additional-scripts/ on the installed system.

Example:

cp my-custom-script.sh additional-scripts/
chmod +x additional-scripts/my-custom-script.sh

Then rebuild the Docker image.

Keyboard Layouts

The current configuration uses Swiss French keyboard (ch-fr). To change:

Edit preseed.cfg and modify:

d-i keyboard-configuration/xkb-keymap select ch(fr)

Common alternatives:

• US: us
• UK: gb
• German (Switzerland): ch(de)
• French (France): fr

Directory Structure

.
├── Dockerfile                 # Docker image definition
├── preseed.cfg               # Debian preseed configuration
├── build-installer.sh        # ISO building script
├── additional-scripts/       # Custom post-installation scripts
│   ├── README.md
│   └── example.sh
├── .dockerignore            # Docker ignore file
└── README.md                # This file

Configuration Details

Localization

• Locale: en_US.UTF-8
• Language: English
• Country: Switzerland
• Timezone: Europe/Zurich

Partitioning

• Uses the entire first disk (/dev/sda)
• Atomic partitioning recipe (one partition for everything)
• Automatically confirms all partitioning decisions

Network

• Automatic network configuration via DHCP
• Default hostname: debian-trixie
• Default domain: localdomain

Packages

• Standard system utilities
• SSH server (OpenSSH)
• sudo

SSH Configuration

• Root login enabled with password authentication
• SSH service enabled on boot

Advanced Usage

Building with Custom Output Directory

mkdir -p /path/to/output
docker run --rm --privileged \
  -v /path/to/output:/output \
  debian-trixie-installer

Interactive Build (for debugging)

docker run -it --rm --privileged \
  -v $(pwd)/output:/output \
  debian-trixie-installer /bin/bash

Then manually run:

/build/build-installer.sh

Security Notes

⚠️ Important Security Considerations:

1. Change Default Passwords: The preseed uses default passwords for demonstration. Always change these before production use.

2. Root Login: SSH root login is enabled for convenience. Consider disabling it after initial setup or using SSH keys only.

3. Network Security: The system uses DHCP by default. Configure static IPs and firewall rules as needed.

4. Update Regularly: Keep the system updated with security patches:

   apt-get update && apt-get upgrade -y

Troubleshooting

ISO Not Booting

• Ensure the ISO was written correctly to USB/VM
• Try using different USB writing tools
• Check BIOS/UEFI boot settings

Build Fails

• Ensure you have sufficient disk space
• Check internet connectivity for ISO download
• Run with --privileged flag for mounting operations

Installation Hangs

• Check network connectivity (needed for package downloads)
• Review preseed configuration syntax
• Boot in expert mode and check system logs

License

This project is provided as-is for educational and deployment purposes.

Contributing

Feel free to submit issues or pull requests for improvements.