A new tool has appeared on Hacker News that brings the isolation of Windows Subsystem for Linux to Linux machines themselves. The NSpawn Subsystem for Linux, or NSL, installs development tools on a Debian, Fedora, or other Linux machine without touching the host system at all. Just as with WSL, each machine retains its packages, services, and files from session to session.
What NSL Does
Each machine retains its packages, services, and files between sessions, just as WSL does. The machines operate as systemd-nspawn containers within a shared VM, starting up only when needed, and they can be used to work inside your host files.
It puts your development tools into a Debian, Fedora, or similar Linux system without touching the host itself, and checks the signed images before putting them to use.
The Shell Command
A shell opens on the default machine with nsl, letting you work within the same files. You can run a single command with nsl run make test, and the exit status returns to the host.
Your Files and Account
The machine mounts your $HOME, /run/media/USER, and /mnt under /mnt/host. It carries over your username, UID, and GID, which means any files you create inside the machine still belong to you. You also receive passwordless sudo access inside the machine.
Ports and Windows
Spin up a development server inside the machine and connect to its forwarded port from host 127.0.0.1. Wayland apps can bring up windows on your desktop via Waypipe.
Seven Signed Distributions
The images come from seven signed distributions:
- Debian
- Ubuntu
- Fedora
- CentOS Stream
- Arch
- openSUSE Tumbleweed
- Leap
Every week, the pictures get rebuilt anew. Before any of them are put to use, NSL checks that they trace back to the signed Frostyard publishing workflow.
Isolation When You Need It
When running software from an unknown source, it’s best to use --isolated. That command puts the program inside its own virtual machine, cutting it off from your host files, desktop, and any host actions.
Runs As Your User
NSL runs as your user. You’ll need the host prerequisites installed first; NSL doesn’t install packages or change device permissions, groups, or sudoers.
Getting Started
The project lists three steps for new users:
- Check the host, install nsl, and create your first machine.
- Learn how the VM runs your machines and connects them to the host.
- Look up commands, settings in
nsl.conf, and published images.
Pre-Release Status
This design’s first release is v0.4.0, and it has not reached a stable version yet. The earlier releases, v0.3.0 and before, are a retired prototype. The tested system runs on Snow Linux 13, an x86-64 distribution, using systemd 261.2, QEMU 10.0.13, virtiofsd 1.13.2, and GNOME Wayland.
Our View
The trick behind NSL is its ability to offer developers an isolated Linux environment that is portable while still working smoothly with the host filesystem.
Before a stable version is ready, users need to be prepared for unfinished work. This notice concerns a design still under development, so rough edges and missing features are part of what comes next.
The concept remains intact. What matters is a portable, isolated Linux environment that integrates smoothly with the host filesystem, and NSL delivers on that promise.
Source material: “Show HN: NSL – WSL for Linux,” frostyard.github.io.
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