Show HN: Smol machines – subsecond coldstart, portable virtual machines

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bbinsquare about 4 hours ago 59 commentsRead Article on github.com

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binsquare•about 4 hours ago

Hello, I'm building a replacement for docker containers with a virtual machine with the ergonomics of containers + subsecond start times.

I worked in AWS previously in the container space + with firecracker. I realized the container is an unnecessary layer that slowed things down + firecracker was a technology designed for AWS org structure + usecase.

So I ended up building a hybrid taking the best of containers with the best of firecracker.

Let me know your thoughts, thanks!

lacoolj•15 minutes ago

What percentage of this code was written by LLM/AI?

PufPufPuf•about 2 hours ago

Hey this is super cool. I've been researching tech like this for my AI sandboxing solution, ended up with Lima+Incus: https://github.com/JanPokorny/locki

My problem with microVMs was that they usually won't run docker / kubernetes, I work on apps that consist of whole kubernetes clusters and want the sandbox to contain all that.

Does your solution support running k3s for example?

fqiao•about 1 hour ago

we will evaluate. I created this issue to track this: https://github.com/smol-machines/smolvm/issues/150

Really appreciate the feedback!

topspin•about 2 hours ago

What is the status of supporting live migration?

That's the one feature of similar systems that always gets left out. I understand why: it's not a priority for "cloud native" workloads. The world, however, has work loads that are not cloud native, because that comes at a high cost, and it always will. So if you'd like a real value-add differentiator for your micro-VM platform (beyond what I believe you already have,) there you go.

Otherwise this looks pretty compelling.

genxy•about 1 hour ago

It helps if you offer a concrete use case, as in how large the heap is, what kinda of blackout period you can handle, and whether the app can handle all of it's open connections being destroyed, etc. The more an app can handle resetting some of it's own state, the easier LM is going to be to implement. If your workload jives with CRIU https://github.com/checkpoint-restore/criu you could do this already.

By what I assume is your definition, there are plenty of "non cloud native" workloads running on clouds that need live migration. Azure and GCP use LM behind the scenes to give the illusion of long uptime hosts. Guest VMs are moved around for host maintenance.

topspin•about 1 hour ago

"Azure and GCP use LM behind the scenes"

As does OCI, and (relatively recently) AWS. That's a lot of votes.

Use case: some legacy database VM needs to move because the host needs maintenance, the database storage (as opposed to the database software) is on a iSCSI/NFS/NVMe-oF array somewhere, and clients are just smart enough to transparently handle a brief disconnect/reconnect (which is built-in to essentially every such database connection pool stack today.)

Use case: a web app platform (node/spring/django/rails/whatever) with a bunch of cached client state needs to move because the host needs maintenance. The developers haven't done all the legwork to make the state survive restart, and they'll likely never get time needed to do that. That's essentially the same use case as previous. It's also rampant.

Use case: a long running batch process (training, etc.) needs to move because reasons, and ops can't wait for it to stop, and they can't kill it because time==money.

"as in how large the heap is"

That's an undecidable moving target, so let the user worry about it. Trust them to figure out what is feasible given the capabilities of their hardware and talent. They'll do fine if you provide the mechanism. I've been shuffling live VMs between hosts for 10+ years successfully, and Qemu/KVM has been capable of it for nearly 20, never mind VMware.

"CRIU"

Dormant, and still containers. Also, it's re-solving solved problems, but with more steps.

fqiao•about 1 hour ago

Really appreciate the suggestion! By "live migration", do you mean keeping the existing files and migrate them elsewhere with the vm?

Thanks

topspin•about 1 hour ago

I mean making any given VM stop on host A and appear on host B; e.g. standard Qemu/KVM:

    virsh migrate --live GuestName DestinationURL

This is feasible when network storage is available and useful when a host needs to be drained for maintenance.

harshdoesdev•about 4 hours ago

+1. i built something similar called shuru.run because i wanted an easy way to set up microVM sandboxes to run some of my AI apps, and firecracker wasn't available for macOS (and, as you said, it is just too heavy for normal user-level workloads).

sahil-shubham•about 3 hours ago

Nice work on Shuru — I remember looking at it when I was researching this space. You went with a Rust wrapper on Apple’s Virtualization framework right?

I have been working on something similar but on top of firecracker, called it bhatti (https://github.com/sahil-shubham/bhatti).

I believe anyone with a spare linux box should be able to carve it into isolated programmable machines, without having to worry about provisioning them or their lifecycle.

The documentation’s still early but I have been using it for orchestrating parallel work (with deploy previews), offloading browser automation for my agents etc. An auction bought heztner server is serving me quite well :)

harshdoesdev•about 2 hours ago

bhatti's cli looks very ergonomic! great job!

also, yes, shuru was (still) a wrapper over the Virtualization.framework, but it now supports Linux too (wrapper over KVM lol)

fqiao•about 3 hours ago

Yes, having a light-weight solution for local devices as well is one primary goal of the design. Another one is to make it easy for hosting, self or managed

thm•about 3 hours ago

You could add OrbStack to the comp. table

fqiao•about 3 hours ago

Will do. Thanks for the suggestion!

sdrinf•about 3 hours ago

hi, great project! Windows support is sorely lacking, though. As someone working a lot with sandboxed LLMs right now, the options-space on windows for sandboxing is _extremely lacking_. Any plans to support it?

fqiao•about 3 hours ago

Hey, thanks so much! yah we will definitely add windows support later. We are exploring how to get this work with WSL and will release it asap. Stay tuned and thanks!

binsquare•about 3 hours ago

Yeah, it's in my mind.

WSL2 runs a linux virtual machine. Need to take some time and care to wire that up, but definitely feasible.

gavinray•about 2 hours ago

The feature that lets you create self-contained binaries seems like a potentially simpler way to package JVM apps than GraalVM Native.

Probably a lot of other neat usecases for this, too

  smolvm pack create --image python:3.12-alpine -o ./python312
  ./python312 run -- python3 --version
  # Python 3.12.x — isolated, no pyenv/venv/conda needed

binsquare•about 2 hours ago

yeah, it's analogous to Electron.

Electron ships your web app bundled with a browser.

Smol machines ship your software packaged with a linux vm. No need for dependency management or compatibility issues because it is baked in.

I think this is how Codex or Claude Code should be shipped by default, to avoid any isolation issues tbh

mrbluecoat•about 1 hour ago

Can .smolmachine be digitally signed and self authenticate when run? Similar to https://docs.sylabs.io/guides/main/user-guide/signNverify.ht...

timsuchanek•12 minutes ago

This is very exciting. It enables a cross platform, language agnostic plugin system, especially for agents, while being safe in a VM.

irickt•about 1 hour ago

Is there a relation to the similarly-purposed and similarly-named https://github.com/CelestoAI/SmolVM

rkagerer•24 minutes ago

I see you support Linux and MacOS hosts. Any Windows support planned?

cr125rider•about 4 hours ago

Great job with the comparison table. Immediately I was like “neat sounds like firecracker” then saw your table to see where it was similar and different. Easy!

Nice job! This looks really cool

fqiao•about 3 hours ago

Thanks so much

lambdanodecore•about 2 hours ago

Basically any open source project nowadays run their software stack in containers often requiring docker compose. Unfortunatley Smol machines do not support Docker inside the microvms and they also do not support nested VMs for things that use Vagrant. I think this is a big drawback.

binsquare•about 2 hours ago

I can support docker - will ship a compatible kernel with the necessary flags in the next release.

lambdanodecore•about 2 hours ago

I tried something like this already, also including nested kvm. I think this will increase the boot time quiet a bit.

Also libkrun is not secure by default. From their README.md:

> The libkrun security model is primarily defined by the consideration that both the guest and the VMM pertain to the same security context. For many operations, the VMM acts as a proxy for the guest within the host. Host resources that are accessible to the VMM can potentially be accessed by the guest through it.

> While defining the security implementation of your environment, you should think about the guest and the VMM as a single entity. To prevent the guest from accessing host's resources, you need to use the host's OS security features to run the VMM inside an isolated context. On Linux, the primary mechanism to be used for this purpose is namespaces. Single-user systems may have a more relaxed security policy and just ensure the VMM runs with a particular UID/GID.

> While most virtio devices allow the guest to access resources from the host, two of them require special consideration when used: virtio-fs and virtio-vsock+TSI.

> When exposing a directory in a filesystem from the host to the guest through virtio-fs devices configured with krun_set_root and/or krun_add_virtiofs, libkrun does not provide any protection against the guest attempting to access other directories in the same filesystem, or even other filesystems in the host.

binsquare•12 minutes ago

Security is a broad topic.

Here's how my perspective:

smolvm operates on the same shared responsibility model as other virtual machines.

VM provides VM-level isolation.

If the user mounts a directory with the capability of symlinks or a host OS with a path for guest software that is designed to escape - that is the responsibility of the user rather than the VM.

Security is not guaranteed by using a specific piece of software, it's a process that requires different pieces for different situations. smolvm can be a part of that process.

genxy•about 1 hour ago

So Vagrant is launching the VM locally, is that why it needs nesting?

Would you be ok with a trampoline that launched the VM as a sibling to the Vagrant VM?

isterin•about 2 hours ago

We’re using smolmachines to create environments for our agents to execute code. It’s been great so far and the team is super responsive. The dev ergonomics are also great.

fqiao•about 1 hour ago

Really appreciate it! Would love to work together to make this easier to use.

ukuina•about 2 hours ago

Doesn't Docker's sbx do this?

https://docs.docker.com/reference/cli/sbx/

binsquare•about 2 hours ago

sandboxing is one of the features of virtual machines.

I'm building a different virtual machine.

0cf8612b2e1e•about 3 hours ago

This looks very cool. Does the VM machinery still work if I run it in a bubblewrap? Can it talk to a GPU?

Can you pipe into one? It would be cute if I could wget in machine 1 and send that result to offline machine 2 for processing.

binsquare•about 3 hours ago

Haven't tried with bubblewrap - but it should.

Yes! GPU passthrough is being actively worked on and will land in next major release: https://github.com/smol-machines/smolvm/pull/96

Yea just tried piping, it works:

``` smolvm machine exec --name m1 -- wget -qO- https://example.com/data.csv \ | smolvm machine exec --name m2 -i -- python3 process.py ```

bch•about 3 hours ago

see too[0][1] for projects of a similar* vein, incl historical account.

*yes, FreeBSD is specifically developed against Firecracker which is specifically avoided w "Smol machines", but interesting nonetheless

[0] https://github.com/NetBSDfr/smolBSD

[1] https://www.usenix.org/publications/loginonline/freebsd-fire...

binsquare•about 2 hours ago

that was one of my inspirations but I don't think they went far enough in innovation.

microvm space is still underserved.

bch•about 2 hours ago

> that was one of my inspirations

Colins FreeBSD work or Emiles NetBSD work?

parasitid•about 1 hour ago

hi! congrats for your work that's really nice.

question: why do you report that qemu is 15s<x<30s? for instance with katacontainers, you can run fast microvms, and even faster with unikernels. what was your setup?

thanks a lot

nonameiguess•about 2 hours ago

What are you actually doing on top of libkrun? Providing really small machine images that boot quickly? If I run the smolvm run --image alpine example, what is "alpine?" Where is that image coming from? Does this have some built-in default registry of machine images it pulls from? Does it need an Internet connection that allows outbound access to wherever this registry runs? Is it one of a default set of pre-built images that comes with the software itself and is stored on my own filesystem? Where are the builds for these images? Where do these machine images end up? ~/.local/share/smolvm/?

chrisweekly•about 1 hour ago

This looks awesome. Thanks for sharing!

akoenig•about 1 hour ago

smolvm is awesome. The team is highly responsive and very experienced. They clearly know what they’re doing.

I’m currently evaluating smolvm for my project, https://withcave.ai, where I’m using Incus for isolation. The initial integration results look very promising!

fqiao•about 1 hour ago

Cannot thank you more for this! Lets' work together to see how we can make this easier for cave!

fqiao•about 4 hours ago

Give it a try folks. Would really love to hear all the feedbacks!

Cheers!

leetrout•about 3 hours ago

why did you seemingly create two HN accounts?

Edit: I see this appears to be a contributor to the project as well. It was not obvious to me.

fqiao•about 3 hours ago

this is me: https://github.com/phooq

@binsquare is this one: https://github.com/BinSquare

messh•about 2 hours ago

https://shellbox.dev is a hosted version of something very similar

harshdoesdev•about 4 hours ago

its a really innovative idea! very interested in the subsecond coldstart claim, how does it achieve that?

fqiao•about 4 hours ago

@binsquare basically brute-force trimmed down unnecessary linux kernel modules, tried to get the vm started with just bare minimum. There are more rooms for improvement for sure. We will keep trying!

deivid•about 3 hours ago

With this approach I managed to get to sub-10ms start (to pid1), if you can accept a few constraints there's plenty of room!

Though my version was only tested on Linux hosts

binsquare•about 2 hours ago

would be interested to see how you do it, how can I connect with you - emotionally?

harshdoesdev•about 3 hours ago

nice! for most local workloads, it is actually sufficient. so, do you ship a complete disk snapshot of the machines?

fqiao•about 3 hours ago

Yes. files on the disks are kept across stop and restart. We also have a pack command to compress the machine as a single file so that it can shipped and rehydrated elsewhere

cperciva•about 2 hours ago

See also SmolBSD -- similar idea, similar name, using NetBSD.

fqiao•about 1 hour ago

I came across SmolBSD before too. Cool project!