Show HN: NSL – WSL for Linux

(frostyard.github.io)

50 points | by bketelsen 3 hours ago

13 comments

  • rao-v 1 hour ago
    I have to say this is nice packaging. It is weirdly not obvious how nice it is to cleanly use a different “machine” inside your desktop.

    I never thought I’d prefer WSL to even my MacBook for working with remote servers and dev but somehow I do.

    I of course know the many ways to roll something like this for myself, yes dev containers are better for many things etc. but it’s wierd how good the ergonomics of a WSL like container are.

    • bketelsen 1 hour ago
      Thanks for saying so! That's exactly why I wrote this. The UX of wsl2 is just right. There are a lot of other ways to accomplish this, but none touch that same experience.
  • 0x457 1 hour ago
    I'm confused why VM + systemd-nspawn? From my understaing WSL 2 runs a single VM + something like systemd-nspawn per "linux installation", but it runs a VM because it needs linux kernel. Why not just do systemd-nspawn if you alread on linux?
    • pkulak 1 hour ago
      Way better isolation, is my guess. Plus, you can use a different kernel this way.

      I used to poo-poo when people said that containers aren't a _real_ security boundary, at least for personal stuff, and not a multi-tenant server. But I bet even mid-tier LLMs can break out of LXC/Docker/nspawn at this point.

      • fhn 34 minutes ago
        can they not break out of a VM?
        • pkulak 33 minutes ago
          It's at least harder! Better chance it'll hit your 5-hour limit before it does. haha
          • esseph 13 minutes ago
            See my response to the above comment
        • esseph 15 minutes ago
          Yes, and have.

          ---

          "During a test conducted by Trail of Bits researcher Artem Dinaburg, a preview version of GPT 5.6-Cyber was tasked with breaking out of a Debian 12 virtual machine. Initially, the agent exploited a known Linux kernel vulnerability, CVE-2026-53359, by developing its own exploit. After the host was updated, the agent found another pathway through libslirp, chaining a known vulnerability (CVE-2026-9539) with a previously unassigned bug to gain arbitrary host memory access. Even after QEMU and libslirp were updated, the agent analyzed system components and constructed a new escape chain using three zero-day vulnerabilities and one KVM flaw that had not yet reached the distribution kernel.

          These findings suggest that general-purpose VMs may not be adequate security boundaries for highly capable AI agents, especially in older systems with delayed security updates. Trail of Bits recommends using specialized isolation systems like Firecracker, restricting VM access, and implementing rapid patching to mitigate these risks."

          ---

          https://www.scworld.com/brief/ai-agent-repeatedly-escapes-vi...

    • bketelsen 1 hour ago
      you could, and if that's your preference https://nspawn.org is just right.
      • 0x457 1 hour ago
        Neat, I wasn't aware of this tool. I just either run nixosContainer in systemd-nspawn or OCI image in systemd-nspawn.
    • delusional 1 hour ago
      Claude told him to do it this way.
      • nateb2022 1 hour ago
        I'd trust OP to make good architectural decisions/provide guidance even if AI mostly wrote the docs and UI. Looking into their GitHub, seems they are an engineering manager at Microsoft and contribute semi regularly to uBlue and Project Bluefin. Should be better quality than some random vibeslopper.
  • bee_rider 45 minutes ago
    The name WSL has always struck me as a bit back area (LSW would seem to make more sense, since it is a Linux subsystem for Windows). I guess they mean it as a Windows Subsystem for Linuxing.

    Anyway, should this be called LSL or WSLL? Or maybe LSWSL.

    • dspillett 23 minutes ago
      It is continuing a historic naming "accident", the precedent having been set by Windows Services for UNIX and similar in the 90s/00s.
  • thayne 2 hours ago
    How does this compare to distrobox?
    • bketelsen 1 hour ago
      Distrobox mounts $HOME in the container at $HOME by default. WSL and NSL do not, and that's my preference. This means you can install tools that change your default path, change your dotfiles, etc, without affecting the host. The other obvious difference is that distrobox is powered by podman or docker, while NSL uses a VM that runs systemd-nspawn containers.
  • michaelastreiko 39 minutes ago
    Nice flip of the WSL idea the other way — simple interop like this keeps a one-person stack from turning into a VM zoo.
  • graemep 2 hours ago
    This is most useful to people who run Linux as their daily driver so rather than saying its like WSL can you explain what it offers that existing Linux containers do not?

    Its also sounds different from WSL which I thought is a VM rather than a container.

    > It's yet another step in my long journey to keep my host installation free from all the changing and breaking dev dependencies that force a reinstall every few months.

    Something that also require a bit of explanation. What do you do that makes this such a common problem.

    • bketelsen 1 hour ago
      WSL2 uses a shared VM that does host integration (networking, shared files, permanent storage for each instance). NSL uses the same model but with Linux native technical implementations.

      As for keeping my host clean - it's the developer's curse that always gets me. Install libWhatever3.2-dev because you need it to compile something, then don't realize until next time you open Chrome that it broke your system in some subtle way. There are dozens of ways to solve this like devcontainers, docker, incus, fully separate or remote vms. I like the WSL2 model so I wanted that same UX.

  • rpcope1 2 hours ago
    So you've just basically reimplemented LXC?
    • pkulak 1 hour ago
      Nope. This is a VM, with containers inside. And the containers weren't "re-implemented", it uses existing systemd containers. That's what I was able to learn by skimming the site for 30 seconds. Did you not even do that? And why even be so condescending to someone else's project?
      • ktm5j 1 hour ago
        Because it does seem like we already have tools that skin this particular cat, it's valid to wonder what value this project provides over existing solutions.. even if they chose the wrong example to compare it to. Why do you think that's condescending?
      • nurettin 1 hour ago
        LXC is a jail and qemu is an extra layer of emulation. Why pay that extra cost? Just because it serves a wsl image isn't really an answer. How is that worth the extra layer?
        • pkulak 1 hour ago
          EDIT to not be a dick about it: I think the key detail here is the difference in isolation between containers and VMs, and where emulation comes in.
          • failbuffer 1 hour ago
            Just a reminder that the Hacker News community generally frowns on caustic dialog. Let's make sure this place doesn't turn into slashdot. :-)
            • pkulak 59 minutes ago
              Agreed. Edited. I do feel like I was just following the existing tone set by OP, but no excuse.
  • dingaling911 1 hour ago
    Looks very cool.

    Now all you have to do is run NSL under WSL.

  • bezko 29 minutes ago
    someone has to ask the question: can you run lsl in wsl?
  • RandomGerm4n 1 hour ago
    There's already Distrobox, which does exactly the same thing but isn't slop.
    • KyleGospo 1 hour ago
      This handles use cases Distrobox can't, they both have a place.
  • varispeed 2 hours ago
    The project is cool, but please use human written text.

    The website's Claudisms are unbearable.

  • the_real_cher 2 hours ago
    IS it LXC containers or docker? Or are you running a custom chroot namespace setup?
    • mhitza 2 hours ago
      Haven't checked the actual project but he does state he uses systemd-nspawn. Which is it's own kind of container runtime.
    • bketelsen 1 hour ago
      none of the above. a single vm started by systemd-vmspawn which then starts one or more containers for your instances using systemd-nspawn. It ends up being fast and lightweight.
    • smw 1 hour ago
      He runs a systemd-nspawnd container in a "small vm", so neither really?