images/ubuntu-build-opennebula-image.sh

#!/bin/sh

# This script generates Ubuntu images for OpenNebula.
#
# Test image locally (without network) with:
#   qemu-system-x86_64 -enable-kvm -m 1G -drive file=$IMAGE,format=qcow2

set -e
set -x

# XXX: Handle command-line arguments?
RELEASE=focal # 20.04
ARCH=amd64
IMAGE_PATH=ubuntu-$RELEASE-$(date --iso-8601).img.qcow2
IMAGE_SIZE=10G
NBD_DEVICE=/dev/nbd0

# TODO: find the package definition and built ourself, publish in some RPM repository.
ONE_CONTEXT_DEB_URL="https://github.com/OpenNebula/addon-context-linux/releases/download/v5.10.0/one-context_5.10.0-1.deb"
ONE_CONTEXT_DEB_PATH=/root/one-context.deb

cleanup() {
	# The order here is important.
	umount /mnt/dev/pts 2>/dev/null || true
	umount /mnt/dev/shm 2>/dev/null || true
	umount /mnt/dev 2>/dev/null || true
	umount /mnt/proc 2>/dev/null || true
	umount /mnt/run 2>/dev/null || true
	umount /mnt/sys 2>/dev/null || true
	umount /mnt/boot 2>/dev/null || true
	umount /mnt 2>/dev/null || true
	qemu-nbd --disconnect "$NBD_DEVICE" || true
}

run_root() {
	chroot /mnt /usr/bin/env \
		PATH=/sbin:/usr/sbin:/bin:/usr/bin \
		sh -c "$*"
}

if [ "$(whoami)" != 'root' ]; then
	echo "This script must be run as root." >&2
	exit 1
fi

if [ $(lsb_release --short --id) != "Ubuntu" ]; then
	echo "WARNING: this script has been designed to run on an Ubuntu system." >&2
	echo "WARNING: Not running Ubuntu. Giving you 5 seconds to abort." >&2
	sleep 5
fi

# Create base QCOW2 image.
qemu-img create -f qcow2 "$IMAGE_PATH" "$IMAGE_SIZE"
modprobe nbd max_part=16
qemu-nbd --connect="$NBD_DEVICE" "$IMAGE_PATH"

# Wait for qemu-nbd to settle.
sleep 1

# Don't forget to cleanup, even if the script crash.
trap cleanup EXIT

# Create partition table, format partitions.
sfdisk --no-reread "$NBD_DEVICE" <<EOF
1M,500M,L,*
,,L
EOF

mkfs.ext4 "${NBD_DEVICE}p1"
mkfs.ext4 "${NBD_DEVICE}p2"

# Mount partitions, install base OS.

mount "${NBD_DEVICE}p2" /mnt
mkdir /mnt/boot
mount "${NBD_DEVICE}p1" /mnt/boot

debootstrap \
	--arch=$ARCH $RELEASE \
	/mnt http://archive.ubuntu.com/ubuntu/

mount --bind /dev /mnt/dev
mount --bind /dev/pts /mnt/dev/pts
mount --bind /dev/shm /mnt/dev/shm
mount --bind /proc /mnt/proc
mount --bind /run /mnt/run
mount --bind /sys /mnt/sys

# Guest networking is to be handled by the one-context package.
# See https://github.com/OpenNebula/addon-context-linux for details.

# Required to resolve package mirror in chroot.
cp /etc/resolv.conf /mnt/etc/resolv.conf

# Initialize /etc/hosts.
cat > /mnt/etc/hosts << EOF
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

EOF

# Configure package sources and update package index.
cat >/mnt/etc/apt/sources.list <<EOF
deb http://archive.ubuntu.com/ubuntu/ $RELEASE main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ $RELEASE-security main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ $RELEASE-updates main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ $RELEASE-backports main restricted universe multiverse
EOF
run_root apt-get update

# Install (magic?) one-context DEB and hope things works as expected.
curl -L "$ONE_CONTEXT_DEB_URL" > "/mnt$ONE_CONTEXT_DEB_PATH"
run_root apt-get -y install "$ONE_CONTEXT_DEB_PATH"
run_root rm "$ONE_CONTEXT_DEB_PATH"

# Manually install legacy network scripts used by one-context.
run_root apt-get -y install ifupdown

# Initalize base services.
run_root systemd-machine-id-setup

run_root ln -sf /usr/share/zoneinfo/UTC /etc/localtime
run_root systemctl enable systemd-timesyncd.service

# Install kernel and bootloader. Do not autoconfigure grub.
run_root echo "grub-pc grub-pc/install_devices_empty boolean true" | debconf-set-selections
run_root DEBIAN_FRONTEND=noninteractive apt-get -y install locales linux-base linux-image-generic grub-pc

# Configure grub.
run_root grub-install --target=i386-pc "${NBD_DEVICE}"
run_root grub-mkconfig -o /boot/grub/grub.cfg

# Install en configure SSH daemon.
run_root apt-get -y install openssh-server

# Generate fstab file.
boot_uuid=$(blkid --match-tag UUID --output value "${NBD_DEVICE}p1")
root_uuid=$(blkid --match-tag UUID --output value "${NBD_DEVICE}p2")
cat >>/mnt/etc/fstab <<EOF
UUID=$boot_uuid /boot ext4 rw,relatime,data=ordered 0 2
UUID=$root_uuid /     ext4 rw,relatime,data=ordered 0 1
EOF

# Reset systemd's environment.
run_root rm -f /etc/machine-id
run_root touch /etc/machine-id
rm -f /var/lib/systemd/random-seed

# Remove temporary files and reclaim freed disk space.
run_root apt-get clean

# Make sure everything is written to disk before exiting.
sync