Automating Ubuntu Installation: Creating Unattended Setup with Preseed Configuration


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For system administrators and DevOps engineers looking to automate Ubuntu deployments, preseed files provide the equivalent functionality to Red Hat's Kickstart. The Debian-installer (d-i) used by Ubuntu fully supports unattended installations through this mechanism.

To implement automated Ubuntu installation, you'll need three key elements:

  • A preseed configuration file (text-based answer file)
  • Modified boot parameters for the installer
  • Proper network accessibility for package retrieval

Here's a basic preseed.cfg file that handles partitioning, user creation, and package selection:

# System language
d-i debian-installer/language string en
d-i debian-installer/country string US

# Network configuration
d-i netcfg/choose_interface select auto
d-i netcfg/get_hostname string ubuntu-auto
d-i netcfg/get_domain string example.com

# Partitioning
d-i partman-auto/method string lvm
d-i partman-auto-lvm/guided_size string max
d-i partman-auto/choose_recipe select atomic

# User setup
d-i passwd/user-fullname string Admin User
d-i passwd/username string admin
d-i passwd/user-password password secure123
d-i passwd/user-password-again password secure123
d-i user-setup/allow-password-weak boolean true

# Package selection
tasksel tasksel/first multiselect standard, ubuntu-server

There are multiple ways to incorporate the preseed file:

Network-based via HTTP

Append this to your kernel boot parameters:

auto url=http://your-server/preseed.cfg

Embedded in ISO

For offline installations, modify the ISO by adding the preseed file to the isolinux/txt.cfg:

label autoinstall
  menu label ^Automated Install
  kernel /install/vmlinuz
  append file=/cdrom/preseed.cfg auto=true priority=critical debian-installer/locale=en_US

Post-Install Scripts

Add custom commands to run after installation:

d-i preseed/late_command string \
  in-target apt-get update; \
  in-target apt-get install -y docker.io; \
  in-target systemctl enable docker

Disk Encryption

For encrypted LVM setups:

d-i partman-auto-crypto/erase_disks boolean true
d-i partman-crypto/passphrase password encryption-pass
d-i partman-crypto/passphrase-again password encryption-pass

When debugging unattended installations:

  • Add fb=false debconf/frontend=noninteractive to boot params
  • Check /var/log/installer/syslog on the target system
  • Test in a VM before deploying to production

For cloud images, combine preseed with cloud-init for complete automation. The Ubuntu server image automatically looks for user-data and meta-data files on the NoCloud datasource.

For system administrators and DevOps engineers automating deployments, Ubuntu provides a powerful unattended installation system through preseed files. This functionality is comparable to Red Hat's Kickstart but uses Debian's debian-installer framework.

You'll need three essential elements:

  1. A modified Ubuntu ISO with preseed.cfg
  2. Kernel boot parameters pointing to your configuration
  3. Proper partitioning and post-install scripts

Here's a basic preseed.cfg example that handles partitioning, package selection, and user setup:


# System language
d-i debian-installer/language string en
d-i debian-installer/country string US

# Network configuration
d-i netcfg/choose_interface select auto
d-i netcfg/get_hostname string ubuntu-auto
d-i netcfg/get_domain string local

# Partitioning (LVM example)
d-i partman-auto/method string lvm
d-i partman-lvm/device_remove_lvm boolean true
d-i partman-auto-lvm/guided_size string max
d-i partman-auto/choose_recipe select atomic

Modify the ISO's boot parameters in isolinux/txt.cfg:


label autoinstall
  menu label ^Automated Install
  kernel /install/vmlinuz
  append auto=true file=/cdrom/preseed.cfg priority=critical debian-installer/locale=en_US keyboard-configuration/layoutcode=us

For PXE boot environments, you can host the preseed file on a web server:


d-i preseed/url string http://192.168.1.100/preseed.cfg

Include custom scripts in your preseed to run after installation:


d-i preseed/late_command string \
  in-target sh -c "apt-get update && apt-get install -y docker-ce"; \
  in-target wget http://example.com/scripts/postinstall.sh -O /root/postinstall.sh; \
  in-target chmod +x /root/postinstall.sh

Monitor the installation process with these techniques:

  • Add fb=false to boot parameters to see console output
  • Check /var/log/installer/syslog on the target system
  • Test in a VM before deploying to production