Reimage any VPS without KVM access

This repo conceptually shows how you can use systemctl soft-reboot to switch to a tmpfs root filesystem, which allows you to reformat and reinstall the OS preinstalled on your VPS with a different OS.

Tar based

mkosi --image=debian-tar build
rsync -zP mkosi.output/debian-tar.tar root@ip:/root/
ssh root@<ip>
mkdir -p /run/nextroot
cd /run/nextroot
tar -xf /local_scratch/image.tar
cp /etc/ssh/ssh_host_* etc/ssh/
systemctl soft-reboot
ssh root@<ip>
cryptsetup close root # Close old root cryptsetup mapper if you have that
# Repartition hard drive and install your system

Image based

mkosi --image=debian-image build
rsync -zP mkosi.output/debian-image.raw root@ip:/root/image.raw
ssh root@<ip>
mount -o remount,size=1700M /run
cp image.raw /run/image.raw
systemd-dissect -M /run/image.raw /run/nextroot
cp /etc/ssh/ssh_host_* /run/nextroot/etc/ssh/
systemctl soft-reboot
ssh root@<ip>
dmsetup remove root # Close old root cryptsetup mapper if you have that
systemd-repart --copy-from --dry-run=no --empty=force /run/image.raw  /dev/vda

Tar based, curl method

If you directly want to deploy an image that's larger than your available memory, you can use the following approach, where you upload the image (age encrypted) to a remote server and redirect the output through decryption onto the disk.

mkosi --image=debian-tar build
rsync -zP mkosi.output/debian-tar.tar root@ip:/root/
ssh root@<ip>
mkdir -p /run/nextroot
cd /run/nextroot
tar -xf /local_scratch/image.tar
cp /etc/ssh/ssh_host_* etc/ssh/
systemctl soft-reboot
ssh root@<ip>
cryptsetup close root # Close old root cryptsetup mapper if you have that
curl -s https://example.com/mkosi.age | age -d | dd of=/dev/sda bs=4M status=progress