#!/bin/sh

if [ $# -ne 2 ]; then
    echo "$0 disk ssh-keyfile"
    echo "   disk: which disk to install to"
    echo "   ssh-keyfile: ssh keys to add into the image"
    exit 1
fi

set -e
set -x

DISK=$1; shift
SSH_KEYS=$1; shift

MAJOR_VERSION=3.13
MINOR_VERSION=5
IMAGE=alpine-minirootfs-$MAJOR_VERSION.$MINOR_VERSION-x86_64.tar.gz

RESOLVCONF=/etc/resolv.conf

working_directory=$(pwd -P)
rootfs_tmpdir=$(mktemp -d)

rootfs_url="http://dl-cdn.alpinelinux.org/alpine/v$MAJOR_VERSION/releases/x86_64/$IMAGE"

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

wget -c "$rootfs_url" -O "$IMAGE"

# Partition disk with 1 Linux partition
sudo sfdisk "$DISK" <<EOF
label: dos
,,L
EOF

# For creation, if an existing filesystem is on the partitions
sudo mkfs.ext4 -F ${DISK}1

sudo mount ${DISK}1 $rootfs_tmpdir

# keep right permissions, use sudo
sudo tar xf $IMAGE -C $rootfs_tmpdir

# Add SSH keys
run_root mkdir -p root/.ssh
sudo cp $SSH_KEYS $rootfs_tmpdir/root/.ssh/authorized_keys
run_root chown root:root /root/.ssh/authorized_keys
run_root chmod 0600 /root/.ssh/authorized_keys
run_root chmod 0700 /root/.ssh

# Import local resolv.conf.
sudo cp "$RESOLVCONF" $rootfs_tmpdir/etc/resolv.conf

run_root apk update
run_root apk add linux-lts openrc udev openssh

run_root rc-update add udev
run_root rc-update add udev-trigger
run_root rc-update add sshd
run_root rc-update add networking
run_root rc-update add hostname
run_root sed -i 's/root:!::0:::::/root:*::0:::::/' /etc/shadow

sudo tee "$rootfs_tmpdir/etc/network/interfaces" <<EOF
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet6 manual
  up /sbin/ip link set \$IFACE up

EOF

sudo tee "$rootfs_tmpdir/etc/hostname" <<EOF
alpine-unconfigured
EOF

# Setup bootloader
for dir in dev proc sys; do
    sudo mount --bind /${dir} ${rootfs_tmpdir}/${dir}
done

run_root apk add grub-bios
run_root grub-install ${DISK}

# Cleanup
run_root rm -f /etc/resolv.conf
for dir in dev proc sys; do
    sudo mount --bind /${dir} ${rootfs_tmpdir}/${dir}
done
sudo umount  $rootfs_tmpdir

sync

echo "${DISK} has been setup with Alpine Linux"

exit 0