nspawn2go

What is it?

An interactive script to provision lightweight Debian VMs. Access your tiny VMs via SSH or VNC.

sudo python3 nspawn2go.py

• Username: debian
• Password: debian (default)
• SSH server port: 2022 (default)
• VNC port: 5901 (default)
• VNC geometry: 1280x720 (default)
  • Try 800x480 for a minimal desktop
• Graphical environments: icewm or xfce4
• Root directory: /var/lib/machines/VMNAME

What is it for?

• Run a tiny graphical desktop:
  • on a dirt-cheap 512mb VPS
  • on a Raspberry Pi in your home network
  • access from any desktop or even from your phone via VNC
• Containerize your servers:
  • Isolate your server configuration from your host
  • All-systemd, no need for third-party tools like Docker
• Portability:
  • Transfer your VM simply by copying the root directory
  • Host can be any systemd distro
  • Host can be bare metal, KVM, VirtualBox, QEMU etc.

How does it work?

Modern systemd-based Linux hosts come equipped with a lightweight container system called nspawn. For most practical purposes, these containers are lightweight, portable VMs.

Instead of a disk image, these containers boot into a directory on your host: /var/lib/machines/VMNAME. That's why systemd-nspawn is known as "chroot on steroids".

Like Docker, you can use these containers to run ad-hoc commands but what makes this most interesting is when you run systemd inside the container to bring up an isolated Linux system.

You can manage these VMs using machinectl (start, stop, reboot, enable, disable).

Instructions

Host dependencies:

• python3
• systemd-container (provides machinectl)
• debootstrap

On Debian/Ubuntu hosts:

apt-get install python3 systemd-container debootstrap

On Arch hosts:

pacman -S python3 debootstrap

Download and run nspawn2go:

wget https://github.com/raw/boronine/nspawn2go/master/nspawn2go.py
sudo python3 nspawn2go.py

You can automate this script using environment variables. See the printed variables as you go through the interactive mode.

Cleanup

If you wish to delete your unused containers you can do it safely like so:

machinectl stop $VMNAME
rm -rf /var/lib/machines/$VMNAME
rm /etc/systemd/nspawn/$VMNAME.nspawn

Caveats

This script disables the --private-users= security feature of systemd-nspawn. This feature maps container UIDs and GIDs to a private set of UIDs and GIDs on the host. We disable it because it makes working with container files from the host a hassle.

This script does not take advantage of systemd-nspawn's --private-network= feature, instead containers share the host network. Pick unique ports for your services if you plan on running multiple instances.