vps2alpine.sh

#!/bin/bash

set -euo pipefail

ALPINE_VERSION_MAJOR="3.23"
ALPINE_VERSION="${ALPINE_VERSION_MAJOR}.4"
ALPINE_ARCH="x86_64"

ALPINE_ROOTFS="https://dl-cdn.alpinelinux.org/alpine/v${ALPINE_VERSION_MAJOR}/releases/${ALPINE_ARCH}/alpine-minirootfs-${ALPINE_VERSION}-${ALPINE_ARCH}.tar.gz"
# Download the Alpine Linux root filesystem

# make damn sure the tools we need are available
if ! command -v curl &> /dev/null || ! command -v tar &> /dev/null; then
    echo "Error: curl and tar are required but not installed."
    exit 1
fi

curl -L -o alpine-rootfs.tar.gz $ALPINE_ROOTFS

# Create a directory for the root filesystem
mkdir -p /x
# Extract the root filesystem
tar -xzf alpine-rootfs.tar.gz -C /x

# Set up resolv.conf for DNS resolution
echo "nameserver 8.8.8.8" > /x/etc/resolv.conf

# Inject our /etc/network/interfaces for DHCP
cat <<EOF > /x/etc/network/interfaces
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp
EOF

# Sketchy: NUKE the existing fs
find / \( ! -path '/dev/*' -and ! -path '/proc/*' -and ! -path '/sys/*' -and ! -path '/x/*' \) -delete || true

# Move the new root filesystem to /
/x/lib/ld-musl-x86_64.so.1 /x/bin/busybox cp -a /x/* /
export PATH="/usr/sbin:/usr/bin:/sbin:/bin"

rm -rf /x alpine-rootfs.tar.gz

apk update
apk add --no-cache alpine-base openssh-server linux-virt grub-efi efibootmgr

# Set up SSH server
echo PermitRootLogin yes >> /etc/ssh/sshd_config
echo 'GRUB_CMDLINE_LINUX_DEFAULT="rootfstype=ext4"' >> /etc/default/grub
rc-update add root boot
rc-update add networking default
rc-update add sshd default
rc-update add mdev sysinit
rc-update add devfs sysinit
rc-update add hostname boot

# Install the bootloader
grub-install --bootloader-id=Alpine
grub-mkconfig -o /boot/grub/grub.cfg

# sh so user can do stuff
echo 'Please "passwd root" right now to set a password for the new root user.' 
sh

# done
sync 
reboot -f