From 91ed2961c6d64e3363890cb7de8466e8bfe99a3d Mon Sep 17 00:00:00 2001
From: Jakub Jirutka <jakub@jirutka.cz>
Date: Tue, 29 Aug 2017 20:03:59 +0200
Subject: [PATCH] Add alpine-make-vm-image script

---
 alpine-make-vm-image | 358 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 358 insertions(+)
 create mode 100755 alpine-make-vm-image

diff --git a/alpine-make-vm-image b/alpine-make-vm-image
new file mode 100755
index 0000000..f173688
--- /dev/null
+++ b/alpine-make-vm-image
@@ -0,0 +1,358 @@
+#!/bin/sh
+# vim: set ts=4:
+#---help---
+# Usage: alpine-make-vm-image [options] [--] <image> [<script> [<script-opts...>]]
+#
+# This script creates a bootable Alpine Linux disk image for virtual machines.
+# Note that it does not create any partitions (it's really not needed),
+# filesystem is created directly on the image.
+#
+# Arguments:
+#   <image>                               Path of disk image to use or create if not exists.
+#
+#   <script>                              Path of script to execute after installing base system in
+#                                         the mounted image and before umounting it.
+#
+#   <script-opts>                         Arguments to pass to the script.
+#
+# Options and Environment Variables:
+#   -f --image-format IMAGE_FORMAT        Format of the disk image (see qemu-img --help).
+#
+#   -s --image-size IMAGE_SIZE            Size of the disk image to create in bytes or with suffix
+#                                         (e.g. 1G, 1024M). Default is 2G.
+#
+#   -i --initfs-features INITFS_FEATURES  List of additional mkinitfs features (basically modules)
+#                                         to be included in initramfs (see mkinitfs -L). "base" and
+#                                         $ROOTFS is always included, don't specify them here.
+#                                         Default is "scsi virtio".
+#
+#   -k --kernel-flavor KERNEL_FLAVOR      The kernel flavour to install; vanilla, hardened,
+#                                         or virthardened. Default is virthardened.
+#
+#      --keys-dir KEYS_DIR                Path of directory with Alpine keys to copy into the image.
+#                                         Default is /etc/apk/keys.
+#
+#   -C --no-cleanup (CLEANUP)             Don't umount and disconnect image when done.
+#
+#   -p --packages PACKAGES                Additional packages to install into the image.
+#
+#   -r --repositories-file REPOS_FILE     Path of repositories file to copy into the image.
+#                                         Default is /etc/apk/repositories.
+#
+#      --rootfs ROOTFS                    Filesystem to create on the image. Default is ext4.
+#
+#   -c --script-chroot (SCRIPT_CHROOT)    Bind <script>'s directory at /mnt inside image and chroot
+#                                         into the image before executing <script>.
+#
+#   -h --help                             Show this help message and exit.
+#
+#   -v --version                          Print version and exit.
+#
+# Each option can be also provided by environment variable. If both option and
+# variable is specified and the option accepts only one argument, then the
+# option takes precedence.
+#
+# https://github.com/jirutka/alpine-make-vm-image
+#---help---
+set -eu
+
+readonly APK='apk --no-progress'
+readonly PROGNAME='alpine-make-vm-image'
+readonly VERSION='0.0.0'
+readonly VIRTUAL_PKG=".make-$PROGNAME"
+
+
+die() {
+	printf '\033[1;31mERROR:\033[0m %s\n' "$@" >&2  # bold red
+	exit 1
+}
+
+einfo() {
+	printf '\n\033[1;36m> %s\033[0m\n' "$@" >&2  # bold cyan
+}
+
+# Prints help and exists with the specified status.
+help() {
+	sed -En '/^#---help---/,/^#---help---/p' "$0" | sed -E 's/^# ?//; 1d;$d;'
+	exit ${1:-0}
+}
+
+cleanup() {
+	set +u
+	trap '' EXIT HUP INT TERM  # unset trap to avoid loop
+
+	cd /
+	if [ -n "$mount_dir" ]; then
+		umount_recursively "$mount_dir" \
+			|| die "Failed to unmount $mount_dir; unmount it and disconnect $nbd_dev manually"
+		rm -Rf "$mount_dir" || :
+	fi
+	qemu-nbd --disconnect "$nbd_dev" \
+		|| die "Failed to disconnect $nbd_dev; disconnect it manually"
+	$APK del $VIRTUAL_PKG
+}
+
+# Attaches the specified image as a NBD block device and prints its path.
+attach_image() {
+	local image="$1"
+	local format="${2:-}"
+	local nbd_dev
+
+	modprobe nbd max_part=0 || true
+	nbd_dev=$(get_available_nbd) \
+		|| die "No available nbd device found!"
+	qemu-nbd --connect="$nbd_dev" ${format:+--format=$format} "$image" \
+		&& echo "$nbd_dev"
+}
+
+# Prints UUID of filesystem on the specified block device.
+blk_uuid() {
+	local dev="$1"
+	blkid "$dev" | sed -En 's/.*UUID="([^"]+)".*/\1/p'
+}
+
+# Prints path of available nbdX device, or returns 1 if not any.
+get_available_nbd() {
+	local dev; for dev in /dev/nbd*; do
+		if [ "$(blockdev --getsize64 "$dev")" -eq 0 ]; then
+			echo "$dev"; return
+		fi
+	done
+	return 1
+}
+
+# Installs tools in the host system needed for creating the specified filesystem.
+install_fs_tools() {
+	local fs="$1"  # filesystem name
+
+	# We need load btrfs module early to avoid the error message:
+	# 'failed to open /dev/btrfs-control'
+	if ! grep -q -w "$fs" /proc/filesystems; then
+		modprobe $fs
+	fi
+
+	local pkg
+	case "$fs" in
+		ext4) pkg='e2fsprogs';;
+		btrfs) pkg='btrfs-progs';;
+		xfs) pkg='xfsprogs';;
+		*) die "Unsupported filesystem: $fs";;
+	esac
+
+	$APK add -t $VIRTUAL_PKG $pkg
+}
+
+# Prepares chroot at the specified path.
+prepare_chroot() {
+	local dest="$1"
+
+	mkdir -p "$dest"/proc "$dest"/dev "$dest"/sys
+	mount -t proc none "$dest"/proc
+	mount --bind /dev "$dest"/dev
+	mount --bind /sys "$dest"/sys
+
+	install -D -m 644 /etc/resolv.conf "$dest"/etc/resolv.conf
+}
+
+# Adds specified services to the runlevel. Current working directory must be
+# root of the image.
+rc_add() {
+	local runlevel="$1"; shift  # runlevel name
+	local services="$@"  # names of services
+
+	local svc; for svc in $services; do
+		mkdir -p etc/runlevels/$runlevel
+		ln -s /etc/init.d/$svc etc/runlevels/$runlevel/$svc
+		echo " * service $svc added to runlevel $runlevel"
+	done
+}
+
+# Installs and configures extlinux.
+setup_extlinux() {
+	local mnt="$1"  # path of directory where is root device currently mounted
+	local root_dev="$2"  # root device
+	local modules="${3:-}"  # modules which should be loaded before pivot_root
+	local default_kernel="${4:-"vanilla"}"  # name of default kernel to boot
+	local kernel_opts="${5:-}"  # default kernel options
+
+	sed -Ei -e "s|^[# ]*(root)=.*|\1=$root_dev|" \
+		-e "s|^[# ]*(default_kernel_opts)=.*|\1=\"$kernel_opts\"|" \
+		-e "s|^[# ]*(modules)=.*|\1=\"$modules\"|" \
+		-e "s|^[# ]*(default)=.*|\1=$default_kernel|" \
+		"$mnt"/etc/update-extlinux.conf
+
+	extlinux --install "$mnt"/boot
+	chroot "$mnt" update-extlinux --warn-only 2>&1 \
+		| grep -Fv 'extlinux: cannot open device /dev' >&2
+}
+
+# Configures mkinitfs.
+setup_mkinitfs() {
+	local mnt="$1"  # path of directory where is root device currently mounted
+	local features="$2"  # list of mkinitfs features
+
+	features=$(printf '%s\n' $features | sort | uniq | xargs)
+
+	sed -Ei "s|^[# ]*(features)=.*|\1=\"$features\"|" \
+		"$mnt"/etc/mkinitfs/mkinitfs.conf
+}
+
+# Unmounts all filesystem under the specified directory tree.
+umount_recursively() {
+	local mount_point="$1"
+	test -n "$mount_point" || return 1
+
+	cat /proc/mounts \
+		| cut -d ' ' -f 2 \
+		| grep "^$mount_point" \
+		| sort -r \
+		| xargs umount -rn
+}
+
+
+#=============================  M a i n  ==============================#
+
+opts=$(getopt -n $PROGNAME -o cCf:hi:k:p:r:s:v \
+	-l image-format:,image-size:,initfs-features:,kernel-flavor:,keys-dir:,no-cleanup,packages:,repositories-file:,rootfs:,script-chroot,help,version \
+	-- "$@") || help 1 >&2
+
+eval set -- "$opts"
+while [ $# -gt 0 ]; do
+	n=2
+	case "$1" in
+		-f | --image-format) IMAGE_FORMAT="$2";;
+		-s | --image-size) IMAGE_SIZE="$2";;
+		-i | --initfs-features) INITFS_FEATURES="${INITFS_FEATURES:-} $2";;
+		-k | --kernel-flavor) KERNEL_FLAVOR="$2";;
+		     --keys-dir) KEYS_DIR="$(realpath "$2")";;
+		-C | --no-cleanup) CLEANUP='no'; n=1;;
+		-p | --packages) PACKAGES="${PACKAGES:-} $2";;
+		-r | --repositories-file) REPOS_FILE="$(realpath "$2")";;
+		     --rootfs) ROOTFS="$2";;
+		-c | --script-chroot) SCRIPT_CHROOT='yes'; n=1;;
+		-h | --help) help 0;;
+		-V | --version) echo "$PROGNAME $VERSION"; exit 0;;
+		--) shift; break;;
+	esac
+	shift $n
+done
+
+: ${CLEANUP:="yes"}
+: ${IMAGE_FORMAT:=}
+: ${IMAGE_SIZE:="2G"}
+: ${INITFS_FEATURES:="scsi virtio"}
+: ${KERNEL_FLAVOR:="virthardened"}
+: ${KEYS_DIR:="/etc/apk/keys"}
+: ${PACKAGES:=}
+: ${REPOS_FILE:="/etc/apk/repositories"}
+: ${ROOTFS:="ext4"}
+: ${SCRIPT_CHROOT:="no"}
+
+[ $# -ne 0 ] || help 1 >&2
+
+IMAGE_FILE="$1"; shift
+SCRIPT=
+[ $# -eq 0 ] || { SCRIPT=$(realpath "$1"); shift; }
+
+[ "$CLEANUP" = no ] || trap cleanup EXIT HUP INT TERM
+
+#-----------------------------------------------------------------------
+einfo 'Installing needed packages on host system'
+
+$APK add -t $VIRTUAL_PKG qemu qemu-img syslinux
+install_fs_tools "$ROOTFS"
+
+#-----------------------------------------------------------------------
+if [ ! -f "$IMAGE_FILE" ]; then
+	einfo "Creating $IMAGE_FORMAT image of size $IMAGE_SIZE"
+	qemu-img create ${IMAGE_FORMAT:+-f $IMAGE_FORMAT} "$IMAGE_FILE" "$IMAGE_SIZE"
+fi
+
+#-----------------------------------------------------------------------
+einfo "Attaching image $IMAGE_FILE as a NBD device"
+
+nbd_dev=$(attach_image "$IMAGE_FILE" "$IMAGE_FORMAT")
+
+#-----------------------------------------------------------------------
+einfo "Formatting image to $ROOTFS"
+
+# syslinux 6.0.3 cannot boot from ext4 w/ 64bit feature enabled
+[ "$ROOTFS" = ext4 ] && mkfs_args='-O ^64bit' || mkfs_args=''
+
+mkfs.$ROOTFS -L root $mkfs_args "$nbd_dev"
+
+root_uuid=$(blk_uuid "$nbd_dev")
+mount_dir=$(mktemp -d /tmp/$PROGNAME.XXXXXX)
+
+#-----------------------------------------------------------------------
+einfo "Mounting image at $mount_dir"
+
+mount "$nbd_dev" "$mount_dir"
+
+#-----------------------------------------------------------------------
+einfo 'Installing base system'
+
+cd "$mount_dir"
+
+mkdir -p etc/apk/keys
+install -m 644 "$REPOS_FILE" etc/apk/repositories
+cp "$KEYS_DIR"/* etc/apk/keys/
+
+$APK add --root . --update-cache --initdb alpine-base
+prepare_chroot .
+
+#-----------------------------------------------------------------------
+einfo "Installing and configuring mkinitfs"
+
+$APK add --root . mkinitfs
+setup_mkinitfs . "base $ROOTFS $INITFS_FEATURES"
+
+#-----------------------------------------------------------------------
+einfo "Installing kernel linux-$KERNEL_FLAVOR"
+
+$APK add --root . linux-$KERNEL_FLAVOR
+
+#-----------------------------------------------------------------------
+einfo 'Setting up extlinux bootloader'
+
+$APK add --root . --no-scripts syslinux
+setup_extlinux . "UUID=$root_uuid" $ROOTFS ${KERNEL_FLAVOR#virt}
+
+cat > etc/fstab <<-EOF
+	# <fs>		<mountpoint>	<type>	<opts>		<dump/pass>
+	UUID=$root_uuid	/		$ROOTFS	noatime		0 1
+EOF
+
+#-----------------------------------------------------------------------
+einfo 'Enabling base system services'
+
+rc_add sysinit devfs dmesg mdev hwdrivers
+rc_add boot modules hwclock swap hostname sysctl bootmisc syslog
+rc_add shutdown killprocs savecache mount-ro
+
+#-----------------------------------------------------------------------
+if [ -n "$PACKAGES" ]; then
+	einfo 'Installing additional packages'
+	$APK add --root . $PACKAGES
+fi
+
+#-----------------------------------------------------------------------
+if [ -n "$SCRIPT" ]; then
+	script_name="${SCRIPT##*/}"
+
+	if [ "$SCRIPT_CHROOT" = 'no' ]; then
+		einfo "Executing script: $script_name $@"
+		"$SCRIPT" "$@" || die 'Script failed'
+	else
+		einfo "Executing script in chroot: $script_name $@"
+		mount --bind "${SCRIPT%/*}" mnt/
+		chroot . sh -c "cd /mnt && ./$script_name \"\$@\"" -- "$@" \
+			|| die 'Script failed'
+	fi
+fi
+
+#-----------------------------------------------------------------------
+einfo 'Completed'
+
+cd - >/dev/null
+ls -lh "$IMAGE_FILE"