Debian Bookworm unattended VM guest installer

Simple script that uses virt-install and configures Debian installer for unattended installation and custom configuration using preseed config in order to create freshly installed Debian KVM guest.

Usage: ./install.sh <GUEST_NAME> [MAC_ADDRESS]

  GUEST_NAME    used as guest hostname, name of the VM and image file name
  MAC_ADDRESS   allows to use specific MAC on the network, this is helpful
                when DHCP server expects your guest to have predefined MAC

Guest OS is minimal no-GUI Debian installation configured with serial console for ability to virsh console <GUEST_NAME>, and OpenSSH server with your SSH key or/and password pre-configured.

It is easy to change the script to add any extra packages and configuration files during unattended installation. The main point of sharing this script is to provide an example of unattended Debian VM creation or a base for your own script.

Prerequisites

apt-get install wget virtinst libvirt-daemon-system qemu-system-x86

Things to check before the first use

• Set your login name and full name in preseed.cfg, update your GitHub name in install.sh in order to install your SSH key for authentication by guest. If you want to use different SSH key, not the one from GitHub, just put authorized_keys to preseed directory and remove wget command that fetches key from GitHub. Update your login name in postinst.sh, where SSH key is installed.
• It's worth considering to enable password authentication in preseed.cfg at least during first run so you could virsh console <GUEST_NAME> in case network connection in guest does not come up with DHCP or IP of the guest is unclear.
• Check RAM size and disk size for the guest in arguments to virst-install in install.sh and modify them as needed.
• Add apt-get install -y <your_favorite> or whatever you want to postinst.sh and any configuration files you want to add to the guest into postinst directory.

Network configuration

Script works with bridged network, guests use DHCP and show up in local network. In case you want something else, replace br0 in arguments to virt-install in install.sh.

Before setting bridged network up:

apt-get install brigde-utils

Example of network configuration in /etc/network/interfaces:

auto lo
iface lo inet loopback

auto br0
iface br0 inet dhcp
        bridge_hw eth0
        bridge_ports eth0
        bridge_stp off
        bridge_fd 1
        bridge_maxage 12

More Info

• https://www.debian.org/releases/stable/example-preseed.txt