#!/bin/sh

set -e
set -x

MAJOR_VERSION=3.10
MINOR_VERSION=3
IMAGE=alpine-minirootfs-$MAJOR_VERSION.$MINOR_VERSION-x86_64.tar.gz
SSH_KEYS=$(cat ~/.ssh/id_rsa.pub)
RESOLVCONF=/etc/resolv.conf

working_directory=$(dirname $0)
rootfs_tmpdir=$(mktemp -d)
rootfs_url="http://dl-cdn.alpinelinux.org/alpine/v$MAJOR_VERSION/releases/x86_64/$IMAGE"

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

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

# Download, extract inital rootfs.
curl "$rootfs_url" -o "$working_directory/$IMAGE"
tar xf $IMAGE -C $rootfs_tmpdir

# Add SSH keys
run_root mkdir root/.ssh
echo $SSH_KEYS > $rootfs_tmpdir/root/.ssh/authorized_keys
run_root chmod 0600 root/.ssh/authorized_keys
run_root chmod 0700 root/.ssh

# Import local resolv.conf.
cat $RESOLVCONF > $rootfs_tmpdir/etc/resolv.conf

# Make sure init is found by the kernel.
run_root ln -s /sbin/init /init

# Layer atop base rootfs.
run_root apk update
run_root apk upgrade
run_root apk add openssh linux-vanilla openrc udev
run_root rc-update add udev
run_root rc-update add sshd

# Generate iniramfs image
(cd $rootfs_tmpdir; find . | cpio -H newc -o | gzip -9 > "$working_directory/alpine-initramfs.gz")
cp $rootfs_tmpdir/boot/vmlinuz-vanilla "$working_directory/alpine-kernel"

# Upload to netboot server.
scp alpine-initramfs.gz alpine-kernel root@netboot.hack4glarus.ungleich.cloud:/var/www/html/

# Cleanup.
rm -r $rootfs_tmpdir
(cd "$working_directory/"; rm vmlinuz-vanilla alpine-kernel $IMAGE)