Install Linux unattended

After reviving my old Thinkpad X230 I looked for a way to automate the installation of a Linux system with a minimal desktop. The idea was to have a “conference laptop” which can be reinstalled after each use.

tl;dr: The code including a detailed README can be found on my GitHub profile.

After building the custom archiso, this article gives an overview of the Ansible code.

Prepare configuration

On the ISO image the installatio process is started by the script perrys-bootstrapper.sh. This script supports of course command line arguments, but it also can read configuration from UEFI variables.

Define hostname:

echo -n myhostname > efi-hostname
efivar --name ed38a5bf-1135-4b0f-aa72-49d30b05dfd4-PerryHostname -w -f efi-hostname

Define flavor:

# one of: debian, ubuntu, archlinux
echo -n debian > efi-flavor
efivar --name ed38a5bf-1135-4b0f-aa72-49d30b05dfd4-PerryFlavor -w -f efi-flavor

Per default the bootstrapper is not started automatically. This can be changed by setting the kernel command line parameter script in Grub:

script=/usr/local/sbin/perrys-bootstrapper.sh

The hostname is then used to find further configuration settings in the inventorys bootstrapparameters object.

Bootstrapping process

The whole process is done by Ansible and consists of three stages.

The first stage will create the filesystem partitions. If encryptedfs=true, it will ask for the passphrase and will then encrypt the root partition. Afterwards, depending on the choosen flavor, pacstrap or debootstrap is executed.

The second stage will use Ansibles chroot connection to run Ansible tasks inside of the newly created Linux system, install packages and bootloader, configure locales and other necessary stuff. Also it will prepare the third stage as a one-shot systemd service.

See the local.yml playbook for more details.

Finally the system reboots and will execute the third stage at first boot to install more stuff like a Desktop Environment. If the hostname is retired, the playbook retired.yml is pulled from the git repository for that.

The third stage can be changed and re-run at any time, since there is a script called /usr/local/sbin/perrys-ansible-apply.sh available on the installed system.