vps2parch/vps2arch

#!/bin/sh

# Copyright 2015, Timothy Redaelli <tredaelli@archlinux.info>

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License at <http://www.gnu.org/licenses/> for
# more details.

: ${ARCH_MIRROR="http://mirror.rackspace.com/archlinux"}

# You don't need to edit anything below this comment

set -e

# Gathering informations about actual environment.
if which wget >/dev/null 2>&1; then
	alias download='wget -nv -O-'
elif which curl >/dev/null 2>&1; then
	alias download='curl -fL'
else
	echo "This script needs curl or wget" >&2
	exit 2
fi

cpu_type=$(uname -m)
findmnt -no SOURCE / | grep -q '^/dev/mapper/' && needs_lvm2=1 || needs_lvm2=0

download_and_extract_bootstrap() {
	local sha1 filename
	download "$ARCH_MIRROR"/iso/latest/sha1sums.txt | grep "$cpu_type.tar.gz" > "sha1sums.txt"
	read -r sha1 filename < "sha1sums.txt"
	download "$ARCH_MIRROR/iso/latest/$filename" > "$filename"
	sha1sum -c sha1sums.txt || exit 1
	tar -xpzf "$filename"
	rm -f "$filename"
	cp -R /etc/resolv.conf "/root.$cpu_type/etc"
	mount --rbind /dev "/root.$cpu_type/dev"
	mount -t proc proc "/root.$cpu_type/proc"
	mount -t sysfs sys "/root.$cpu_type/sys"
	# FIXME support multiple partitions
	mount --bind / "/root.$cpu_type/mnt"
	findmnt /boot >/dev/null && mount --bind /boot "/root.$cpu_type/mnt/boot"
	# Workaround for Debian
	mkdir -p "/root.$cpu_type/run/shm"
}

chroot_exec() {
	chroot "/root.$cpu_type" /bin/bash -c "$*"
}

configure_chroot() {
	# Install and initialize haveged if needed
	if ! pidof haveged >/dev/null; then
		download "https://www.archlinux.org/packages/extra/$cpu_type/haveged/download/" > "/root.$cpu_type/haveged.pkg.tar.xz"
		chroot_exec 'pacman --noconfirm -U /haveged.pkg.tar.xz && haveged'
		rm -f "/root.$cpu_type/haveged.pkg.tar.xz"
	fi
	# FIXME support multiple mirrors
	echo 'Server = '"$ARCH_MIRROR"'/$repo/os/$arch' >> "/root.$cpu_type/etc/pacman.d/mirrorlist"
	chroot_exec 'pacman-key --init && pacman-key --populate archlinux'

	# Generate fstab
	chroot_exec 'genfstab /mnt >> /etc/fstab'
}

save_root_pass() {
	grep '^root:' /etc/shadow > "/root.$cpu_type/root.passwd"
	chmod 0600 "/root.$cpu_type/root.passwd"
}

download_and_install_busybox() {
	download "https://www.archlinux.org/packages/community/$cpu_type/busybox/download/" > "/root.$cpu_type/busybox.pkg.tar.xz"
	chroot_exec 'pacman --noconfirm -U /busybox.pkg.tar.xz'
	rm -f "/root.$cpu_type/busybox.pkg.tar.xz"
}

delete_all() {
	# Delete *all* files from /
	find / \( ! -path '/dev/*' -and ! -path '/proc/*' -and ! -path '/sys/*' -and ! -path '/selinux/*' -and ! -path "/root.$cpu_type/*" \) -delete 2>/dev/null || true
}

install_packages() {
	local packages="base grub openssh"
	if [ $needs_lvm2 -eq 1 ]; then
		packages="$packages lvm2"
	fi
	# You can't use chroot_exec here, because the root filesystem was deleted!
	"/root.$cpu_type/usr/bin/busybox" chroot "/root.$cpu_type" /usr/bin/pacstrap /mnt $packages
	cp -L "/root.$cpu_type/etc/resolv.conf" /etc
}

restore_root_pass() {
	sed -i '/^root:/d' /etc/shadow
	cat "/root.$cpu_type/root.passwd" >> /etc/shadow
}

cleanup() {
	mv "/root.$cpu_type/etc/fstab" "/etc/fstab"
	awk "/\/root.$cpu_type/ {print \$2}" /proc/mounts | sort -r | xargs umount -nl
	rm -rf "/root.$cpu_type/"
}

configure_bootloader() {
	local root_dev=$(findmnt -no SOURCE /) root_devs= tmp=

	# If you are still using eth* as interface name, disable "strange" ifnames
	if grep -q '^\s*eth' /proc/net/dev; then
		sed -i.bak 's/GRUB_CMDLINE_LINUX_DEFAULT="/&net.ifnames=0 /' /etc/default/grub
	fi

	if [ $needs_lvm2 -eq 1 ]; then
		local vg
		# Some distro doesn't use lvmetad by default
		sed -i.bak 's/use_lvmetad = 1/use_lvmetad = 0/g' /etc/lvm/lvm.conf
		vg=$(lvs --noheadings $root_dev | awk '{print $2}')
		root_dev=$(pvs --noheadings | awk -v vg="$vg" '($2 == vg) { print $1 }')
	fi
	for root_dev in $root_dev; do
		tmp=$(lsblk -npsro NAME "$root_dev" | tail -n1)
		case " $root_devs " in
		*" $tmp "*) 	;;
		*)		root_devs="${root_devs:+$root_devs }$tmp"	;;
		esac
	done
	grub-mkconfig > /boot/grub/grub.cfg
	for root_dev in $root_devs; do
		grub-install --target=i386-pc --recheck "$root_dev"
	done

	if [ $needs_lvm2 -eq 1 ]; then
		mv /etc/lvm/lvm.conf.bak /etc/lvm/lvm.conf
		sed -i '/HOOKS/s/block/& lvm2/' /etc/mkinitcpio.conf
		mkinitcpio -p linux
	fi
}

configure_network() {
	local gateway dev ip

	read -r _ _ gateway _ dev <<-EOF
		$(ip route show 0.0.0.0/0)
	EOF

	ip=$(ip addr show dev "$dev" | awk '($1 == "inet") { print $2 }')

	cat > /etc/systemd/network/default.network <<-EOF
		[Match]
		Name=$dev

		[Address]
		Address=$ip

		[Route]
		Gateway=$gateway
	EOF

	systemctl enable systemd-networkd sshd
}

finalize() {
	cat <<-EOF
		Hi,
		your VM has successfully been reimaged with Arch Linux.

		This script configured grub as bootloader and systemd-networkd for networking.

		When you are finished with your post-installation, you'll need to reboot the VM the rough way:
		# sync ; reboot -f

		Then you'll be able to connect to your VM using SSH and to login using your old root password.
	EOF
}

cd /
download_and_extract_bootstrap
configure_chroot
save_root_pass
download_and_install_busybox
delete_all
install_packages
restore_root_pass
cleanup
configure_bootloader
configure_network
finalize