mavdol04 (u/mavdol04)

mavdol04 commented on Show HN: Sandboxing untrusted code using WebAssembly github.com/mavdol/capsule... · Posted by u/mavdol04

zachrip · 8 days ago

Is the code in the eval also turned into wasm first then? Does this work as a JIT for wasm?

mavdol04 · 8 days ago

It actually works a bit differently. The eval is executed by the interpreter running inside the isolated wasm sandbox (StarlingMonkey). You can think of it as each sandbox having its own dedicated JavaScript engine.

mavdol04 commented on Show HN: Sandboxing untrusted code using WebAssembly github.com/mavdol/capsule... · Posted by u/mavdol04

bigblind · 10 days ago

This looks very neat indeed! Are there any plans to adding network limits? Like, you might want to avoid an agent running code that just requests a resource in a loop, or downloads massive amounts of data.

mavdol04 · 10 days ago

Thanks! Not yet, but that's a great idea. I could definitely add it to the roadmap.

mavdol04 commented on Show HN: Sandboxing untrusted code using WebAssembly github.com/mavdol/capsule... · Posted by u/mavdol04

zachrip · 10 days ago

Would like to see the eval version - the dialogue version just seems like normal code with extra steps?

mavdol04 · 10 days ago

yeah, the previous example was quite basic. I will write a complete example for that, but here is how you can run dynamic code:

   import { task } from "@capsule-run/sdk";

   export default task({
     name: "main",
     compute: "HIGH",
   }, async () => {
     const untrustedCode = "const x = 10; x * 2 + 5;";
     const result = eval(untrustedCode);
     return result;
   });

Hope that helps!

mavdol04 commented on Show HN: Sandboxing untrusted code using WebAssembly github.com/mavdol/capsule... · Posted by u/mavdol04

simonw · 10 days ago

You can run libraries like Pandas in WebAssembly in Pyodide - in fact Pandas works already. Here's a demo I built with it a while ago: https://tools.simonwillison.net/pyodide-bar-chart

It's not too hard to compile a C extension for Python to a WebAssembly and bundle that in a .so file in a wheel. I did an experiment with that the other day: https://github.com/simonw/tiny-haversine?tab=readme-ov-file#...

mavdol04 · 10 days ago

I would love for the component model tooling to reach that level of maturity.

Since the runtime uses standard WASI and not Emscripten, we don't have that seamless dynamic linking yet. It will be interesting to see how the WASI path eventually converges with what Pyodide can do today regarding C-extensions.

mavdol04 commented on Show HN: Sandboxing untrusted code using WebAssembly github.com/mavdol/capsule... · Posted by u/mavdol04

simonw · 10 days ago

The decorator syntax is neat but confusing to me - I would need to understand exactly what it's doing in order to trust it.

I'd find this a lot easier to trust it if had the Python code that runs in WASM as an entirely separate Python file, then it would be very clear to me which bits of code run in WASM.

mavdol04 · 10 days ago

Thanks for the feedback! What do you think about running the separate file directly from the decorator?

mavdol04 commented on Show HN: Sandboxing untrusted code using WebAssembly github.com/mavdol/capsule... · Posted by u/mavdol04

yohguy · 10 days ago

It looks really promising but I would love more examples as to how to actually use this with AI agents. Reading the homepage it is not clear if we are meant to have the Agent spun up and act fully in the sandbox (something like the HTTP example) or do we take the result code message from an AI agent and then run it dynamically (with eval?).

That being said this is useful even if it wasn't for the running AI agent code aspect, being able to limit ram and cpu usage and time outs makes it easier to run coding based games/applications safely (like battle snakes and Leetcode)

mavdol04 · 10 days ago

Thanks! Got it, I will add more examples for that. Currently you can do both: run dynamically untrusted code with eval, or run fully encapsulated logic (like in the existing examples).

I made a small example that might give you a better idea (it's not eval, but shows how to isolate a specific data processing task): https://github.com/mavdol/capsule/tree/main/examples/javascr...

And yes, you are spot on regarding LeetCode platforms. The resource limits are also designed for that kind of usage.

mavdol04 commented on Show HN: Sandboxing untrusted code using WebAssembly github.com/mavdol/capsule... · Posted by u/mavdol04

gregpr07 · 10 days ago

Why go this route? Why Python is more powerful than JS is mostly because of third party plugins like pandas which are excplicitly not supported (C bindings, is this possible to fix?)...

At that point it might be just easier to convince the model to write JS directly

mavdol04 · 10 days ago

I understand your point. I added native Python support because C extensions will eventually become compatible. Also, we might see more libraries built with Rust extensions appearing, which will be much easier to port to Wasm.

mavdol04 commented on Show HN: Sandboxing untrusted code using WebAssembly github.com/mavdol/capsule... · Posted by u/mavdol04

koolala · 10 days ago

It seems import to highlight these more. Aren't all the limitations of using this based around their limitations?

componentize-py – Python to WebAssembly Component compilation

+

jco – JavaScript toolchain for WebAssembly Components

I'm curious how Wasi 0.3 cross language components will go for something like this.

mavdol04 · 10 days ago

I recreated many Node.js built-ins so compatibility is actually quite extended.

For Python, the main limitation is indeed C extensions. I'm looking for solutions. the move to WASI 0.3 will certainly help with that.