prep-image

#!/usr/bin/env bash
#
# Generates customized cloud images (highly opinionated).  Supports the following releases:
#   - Debian 11 (bullseye)
#   - Debian 12 (bookworm)
#
# Performs the following operations on the image:
#   - Sets the default locale to en_US.UTF8 and generates locales.

# Requires libguestfs-tools

readonly DEBIAN_BASE_URL="https://cloud.debian.org/images/cloud"

set -o errexit
set -o pipefail
set -o nounset

function die() {
	echo "$*" 1>&2
	exit -1
}

IMAGE_FILENAME=""
IMAGE_URL=""
CUSTOMIZED_FILENAME=""
DEFAULT_LOCALE="en_US.UTF-8"
DHCP_INTERFACE="${DHCP_INTERFACE:-ens18}"

#
# Extra commands to be run on the image.
#
declare -a EXTRA_COMMANDS
EXTRA_COMMANDS=()
# Set default locale to en_US.UTF-8 and generate locales
EXTRA_COMMANDS+=('echo "locales locales/default_environment_locale select '${DEFAULT_LOCALE}'" | sudo debconf-set-selections')
EXTRA_COMMANDS+=('echo "locales locales/locales_to_be_generated multiselect '${DEFAULT_LOCALE}' UTF-8" | debconf-set-selections')
EXTRA_COMMANDS+=('sed -i "s/^# '${DEFAULT_LOCALE}' UTF-8/'${DEFAULT_LOCALE}' UTF-8/" /etc/locale.gen')
EXTRA_COMMANDS+=('dpkg-reconfigure --frontend noninteractive locales')
# Limit dhcp on initial boot
EXTRA_COMMANDS+=('sed -i "s/^source-directory \/run\/network\/interfaces.d/# source-directory \/run\/network\/interfaces.d/" /etc/network/interfaces')
EXTRA_COMMANDS+=('echo "source /run/network/interfaces.d/'${DHCP_INTERFACE}'" >> /etc/network/interfaces')

printf "\n ** Cloud image preparation **\n\n"

###############################################################################
# Select a distro                                                             #
###############################################################################
PS3=$'\n'"Select a distro: "
select release in "Debian Bullseye" "Debian Bookworm" "Quit"; do
	case $release in
		"Debian Bullseye")
			IMAGE_FILENAME="debian-11-generic-amd64.qcow2"
			IMAGE_URL="${DEBIAN_BASE_URL}/bullseye/latest/${IMAGE_FILENAME}"
			break
			;;
		"Debian Bookworm")
			IMAGE_FILENAME="debian-12-generic-amd64.qcow2"
			IMAGE_URL="${DEBIAN_BASE_URL}/bookworm/latest/${IMAGE_FILENAME}"
			break
			;;
		"Quit")
			exit -1
			;;
		*)
			echo "Invalid selection"
			;;
	esac
done

printf "\nBuilding a custom cloud image for $release.\n\n"

CUSTOMIZED_FILENAME="$(basename ${IMAGE_FILENAME} .qcow2).customized.qcow2"

###############################################################################
# Download the base image if it does not exist
###############################################################################
if [[ ! -f "$IMAGE_FILENAME" ]]; then
	printf "Image $IMAGE_FILENAME not available locally.\nDownloading from ${IMAGE_URL}...\n\n"
	curl -L -o "$IMAGE_FILENAME" "$IMAGE_URL"
else
	printf "Found existing image ${IMAGE_FILENAME}.  Skipping download.\n"
fi

###############################################################################
# Prepare for customizations
###############################################################################
[[ -f "$CUSTOMIZED_FILENAME" ]] && rm "$CUSTOMIZED_FILENAME"
cp "$IMAGE_FILENAME" "$CUSTOMIZED_FILENAME"


###############################################################################
# Build the virt-customize args
###############################################################################
declare -a CUSTOMIZE_ARGS
CUSTOMIZE_ARGS=("-a" "$CUSTOMIZED_FILENAME")
CUSTOMIZE_ARGS+=("--install" "qemu-guest-agent")
CUSTOMIZE_ARGS+=("--install" "xfsprogs")
for cmd in "${EXTRA_COMMANDS[@]}"; do
	CUSTOMIZE_ARGS+=("--run-command" "${cmd}")
done
CUSTOMIZE_ARGS+=("--truncate" "/etc/machine-id")

###############################################################################
# Execute!
###############################################################################
printf "\nPreparing custom image ${CUSTOMIZED_FILENAME}...\n\n"
(
	set -x; virt-customize "${CUSTOMIZE_ARGS[@]}"
)

printf "\nCustomized image is available: $CUSTOMIZED_FILENAME\n"