#!/bin/sh

# This script generates Debian images for Uncloud.
#
# 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=buster # 10
ARCH=amd64
IMAGE_PATH=debian-uncloud-$RELEASE-$(date --iso-8601).img.qcow2
IMAGE_SIZE=10G
NBD_DEVICE=/dev/nbd0
APT_MIRROR=http://deb.debian.org/debian

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)" != "Debian" ]; then
	echo "WARNING: this script has been designed to run on a Debian system." >&2
	echo "WARNING: Not running Debian. 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 $APT_MIRROR

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

# 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

# Accept router advertisements for SLAAC.
run_root sysctl -w net.ipv6.conf.all.accept_ra=1

# Configure package sources and update package index.
cat >/mnt/etc/apt/sources.list <<EOF
deb $APT_MIRROR $RELEASE main
deb-src $APT_MIRROR $RELEASE main
deb $APT_MIRROR $RELEASE-updates main
deb-src $APT_MIRROR $RELEASE-updates main

deb http://security.debian.org/debian-security $RELEASE/updates main
deb-src http://security.debian.org/debian-security $RELEASE/updates main
EOF
run_root apt-get update

# Initialize 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

# 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

# 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-$ARCH grub-pc

# Configure grub.
run_root grub-install --target=i386-pc "${NBD_DEVICE}"
sed -i "s/GRUB_CMDLINE_LINUX_DEFAULT=\"quiet\"/GRUB_CMDLINE_LINUX_DEFAULT=\"\"/" /mnt/etc/default/grub
sed -i "s/GRUB_CMDLINE_LINUX=\"\"/GRUB_CMDLINE_LINUX=\"root=UUID=$root_uuid\"/" /mnt/etc/default/grub
run_root grub-mkconfig -o /boot/grub/grub.cfg

# Install en configure SSH daemon. The service is enabled by default.
run_root apt-get -y install openssh-server

# Use haveged as entropy source.
run_root apt-get -y install haveged

# Manually install uncloud-init.
uncloud_init_dir=/tmp/uncloud-init
run_root apt-get install -y git curl grep make

mkdir -p "$uncloud_init_dir"
run_root git clone https://code.ungleich.ch/uncloud/uncloud-init.git "$uncloud_init_dir"
run_root make -C "$uncloud_init_dir" install
run_root rm -r "$uncloud_init_dir"

run_root systemctl enable uncloud-init

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

# Manually install uncloud-init.
uncloud_init_dir=/tmp/uncloud-init
run_root apt-get install -y git curl grep make

mkdir -p "$uncloud_init_dir"
run_root git clone https://code.ungleich.ch/uncloud/uncloud-init.git "$uncloud_init_dir"
run_root make -C "$uncloud_init_dir" install
run_root rm -r "$uncloud_init_dir"

run_root systemctl enable uncloud-init

# Install RDNSSD for DNS discovery from router advertisement. The service is enabled by default.
run_root apt-get install -y rdnssd

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

# Remove resolv.conf, as it is handled by uncloud-init.
run_root rm /etc/resolv.conf

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