mkimage-arch.sh

#!/usr/bin/env bash
# Generate a minimal filesystem for archlinux and load it into the local
# docker as "archlinux"
# requires root
set -e

# reset umask to default
umask 022

hash pacstrap &> /dev/null || {
	echo "Could not find pacstrap. Run pacman -S arch-install-scripts"
	exit 1
}

hash expect &> /dev/null || {
	echo "Could not find expect. Run pacman -S expect"
	exit 1
}

export LANG="C.UTF-8"

ROOTFS=$(mktemp -d ${TMPDIR:-/var/tmp}/rootfs-archlinux-XXXXXXXXXX)
chmod 755 $ROOTFS

# required packages
PKGREQUIRED=(
	bash
	haveged
	pacman
	pacman-mirrorlist
)

# packages to ignore for space savings
PKGIGNORE=(
	dhcpcd
	diffutils
	file
	inetutils
	iproute2
	iputils
	jfsutils
	licenses
	linux
	linux-firmware
	lvm2
	man-db
	man-pages
	mdadm
	nano
	netctl
	openresolv
	pciutils
	pcmciautils
	psmisc
	reiserfsprogs
	s-nail
	sysfsutils
	systemd-sysvcompat
	usbutils
	vi
	which
	xfsprogs
)

PKGREMOVE=(
	gawk
	haveged
	less
	linux-libre
	linux-libre-firmware
)

PKGREQUIRED="${PKGREQUIRED[*]}"
IFS=','
PKGIGNORE="${PKGIGNORE[*]}"
unset IFS
PKGREMOVE="${PKGREMOVE[*]}"

arch="$(uname -m)"
case "$arch" in
	armv*)
		if pacman -Q archlinuxarm-keyring > /dev/null 2>&1; then
			pacman-key --init
			pacman-key --populate archlinuxarm
		else
			echo "Could not find archlinuxarm-keyring. Please, install it and run pacman-key --populate archlinuxarm"
			exit 1
		fi
		PACMAN_CONF=$(mktemp ${TMPDIR:-/var/tmp}/pacman-conf-archlinux-XXXXXXXXX)
		version="$(echo $arch | cut -c 5)"
		sed "s/Architecture = armv/Architecture = armv${version}h/g" './mkimage-archarm-pacman.conf' > "${PACMAN_CONF}"
		PACMAN_MIRRORLIST='Server = http://mirror.archlinuxarm.org/$arch/$repo'
		PACMAN_EXTRA_PKGS='archlinuxarm-keyring'
		EXPECT_TIMEOUT=1800 # Most armv* based devices can be very slow (e.g. RPiv1)
		ARCH_KEYRING=archlinuxarm
		DOCKER_IMAGE_NAME="armv${version}h/archlinux"
		;;
	*)
		PACMAN_CONF='./mkimage-arch-pacman.conf'
		PACMAN_MIRRORLIST='Server = https://mirrors.kernel.org/archlinux/$repo/os/$arch'
		PACMAN_EXTRA_PKGS=''
		EXPECT_TIMEOUT=60
		ARCH_KEYRING=archlinux
		DOCKER_IMAGE_NAME=archlinux
		;;
esac

export PACMAN_MIRRORLIST

expect << EOF
	set send_slow {1 .1}
	proc send {ignore arg} {
		sleep .1
		exp_send -s -- \$arg
	}
	set timeout $EXPECT_TIMEOUT

	spawn pacstrap -C $PACMAN_CONF -c -d -G -i $ROOTFS base $PKGREQUIRED $PACMAN_EXTRA_PKGS --ignore $PKGIGNORE
	expect {
		-exact "anyway? \[Y/n\] " { send -- "n\r"; exp_continue }
		-exact "(default=all): " { send -- "\r"; exp_continue }
		-exact "installation? \[Y/n\]" { send -- "y\r"; exp_continue }
		-exact "delete it? \[Y/n\]" { send -- "y\r"; exp_continue }
	}
EOF

arch-chroot $ROOTFS /bin/sh -c 'rm -r /usr/share/man/*'
arch-chroot $ROOTFS /bin/sh -c "haveged -w 1024; pacman-key --init; pkill haveged; pacman-key --populate $ARCH_KEYRING"
arch-chroot $ROOTFS /bin/sh -c "ln -sf /usr/share/zoneinfo/UTC /etc/localtime"
arch-chroot $ROOTFS /bin/sh -c "for pkg in $PKGREMOVE; do if pacman -Qi \$pkg > /dev/null 2>&1; then pacman -Rs --noconfirm \$pkg; fi; done"
echo 'en_US.UTF-8 UTF-8' > $ROOTFS/etc/locale.gen
arch-chroot $ROOTFS locale-gen

# udev doesn't work in containers, rebuild /dev
DEV=$ROOTFS/dev
rm -rf $DEV
mkdir -p $DEV
mknod -m 666 $DEV/null c 1 3
mknod -m 666 $DEV/zero c 1 5
mknod -m 666 $DEV/random c 1 8
mknod -m 666 $DEV/urandom c 1 9
mkdir -m 755 $DEV/pts
mkdir -m 1777 $DEV/shm
mknod -m 666 $DEV/tty c 5 0
mknod -m 600 $DEV/console c 5 1
mknod -m 666 $DEV/tty0 c 4 0
mknod -m 666 $DEV/full c 1 7
mknod -m 600 $DEV/initctl p
mknod -m 666 $DEV/ptmx c 5 2
ln -sf /proc/self/fd $DEV/fd

tar --numeric-owner --xattrs --acls -C $ROOTFS -c . | docker import - $DOCKER_IMAGE_NAME
docker run --rm -t $DOCKER_IMAGE_NAME echo Success.
rm -rf $ROOTFS