systemd-nspawn containers with various Linux distributions: Alpine, Arch Linux, Ubuntu

## alpine-container.sh
#!/bin/bash -e
# Creates a systemd-nspawn container with Alpine

MIRROR=http://nl.alpinelinux.org/alpine
ARCH=x86_64
VERSION=v3.10
APKTOOLS_VERSION=2.10.4-r2


if [ $UID -ne 0 ]; then
	echo "run this script as root" >&2
	exit 1
fi

if [ -z "$1" ]; then
	echo "Usage: $0 <destination>" >&2
	exit 0
fi

dest="$1"
apkdir=$(mktemp -d)
guestarch=x86
[ "$(uname -m)" == x86_64 ] && guestarch=x86_64

wget -qO- $MIRROR/latest-stable/main/x86/apk-tools-static-$APKTOOLS_VERSION.apk \
	| tar -xz -C $apkdir || \
	{ echo "Couldn't download apk-tools, the version might have changed..."; exit 1; }

$apkdir/sbin/apk.static \
	-X $MIRROR/$VERSION/main -U --arch $guestarch \
	--allow-untrusted --root "$dest" \
	--initdb add alpine-base

mkdir -p "$dest"/{etc/apk,root}
printf '%s/%s/main\n' $MIRROR $VERSION >"$dest"/etc/apk/repositories
sed '/tty[0-9]:/ s/^/#/' -i "$dest"/etc/inittab
printf 'console::respawn:/sbin/getty 38400 console\n' >>"$dest"/etc/inittab
for s in hostname bootmisc syslog; do
	ln -s /etc/init.d/$s "$dest"/etc/runlevels/boot/$s
done
for s in killprocs savecache; do
	ln -s /etc/init.d/$s "$dest"/etc/runlevels/shutdown/$s
done


rm -r $apkdir
echo ""
echo "Alpine $VERSION container was created successfully."

## arch-container.sh
#!/bin/bash -e
# Creates a systemd-nspawn container with Arch Linux

MIRROR=http://mirror.fra10.de.leaseweb.net/archlinux
ISO_DATE=2019.09.01
PKG_GROUPS="base"


if [ $UID -ne 0 ]; then
	echo "run this script as root" >&2
	exit 1
fi

if [ -z "$1" ]; then
	echo "Usage: $0 <destination>" >&2
	exit 0
fi

dest="$1"
tarfile=$(mktemp)

wget $MIRROR/iso/$ISO_DATE/archlinux-bootstrap-$ISO_DATE-x86_64.tar.gz -O $tarfile
mkdir "$dest"
tar -xzf $tarfile -C "$dest" --strip-components=1

rm "$dest"/etc/resolv.conf "$dest"/etc/securetty
printf 'Server = %s/$repo/os/$arch\n' $MIRROR >"$dest"/etc/pacman.d/mirrorlist
cat >"$dest"/setup.sh <<SCRIPT
pacman-key --init
pacman-key --populate archlinux
pacman -Sy
# avoid installing the kernel
pacman -Sg ${PKG_GROUPS} | while read _ p;do [[ "\$p" == "linux"* ]]||echo "\$p";done | pacman -S --noconfirm --needed -
rm /setup.sh
SCRIPT
systemd-nspawn -q -D "$dest" sh /setup.sh


rm $tarfile
echo ""
echo "Arch $ISO_DATE container was created successfully."

## ubuntu-container.sh
#!/bin/bash -e
# Creates a systemd-nspawn container with Ubuntu

CODENAME=bionic


if [ $UID -ne 0 ]; then
	echo "run this script as root" >&2
	exit 1
fi

if [ -z "$1" ]; then
	echo "Usage: $0 <destination>" >&2
	exit 0
fi

dest="$1"
rootfs=$(mktemp)

wget "http://cloud-images.ubuntu.com/${CODENAME}/current/${CODENAME}-server-cloudimg-amd64-root.tar.xz" -O $rootfs
mkdir -p "$dest"
tar -xaf $rootfs -C "$dest"

sed '/^root:/ s|\*||' -i "$dest/etc/shadow"
rm "$dest/etc/resolv.conf" "$dest/etc/securetty"
disable="ebtables rsync systemd-timesyncd snapd snapd.seeded"
disable="$disable networkd-dispatcher systemd-networkd systemd-networkd-wait-online systemd-resolved"
for s in $disable; do
	rm -f "$dest/etc/systemd/system/"*.target.wants"/$s.service" "$dest"/etc/rc[S5].d/S??"$s"
done
# ssh and iscsi cause startup to hang
systemd-nspawn -q -D "$dest" apt-get -qq purge -y openssh-server open-iscsi


rm $rootfs
echo ""
echo "Ubuntu $CODENAME container was created successfully."