webcontainer-core VS luau

How does it work? There is no backend whatsoever. The API Security Academy leverages WebContainers, a new technology that allows running full-blown node instances directly in the browser. Each WebContainer contains a live GraphQL application, so you'll not only understand why a vulnerability is risky, but also how to exploit it and, most importantly, how to fix it.

StackBlitz made the claim "... run Node.js, entirely inside your browser" #658, then had to revise it's claim to "We currently do not expose a way to use WebContainer outside of StackBlitz.com,".

> Wasm though seems like the likely general heir, and will have many different offerings for how to do that (Deno being one!).

I was recently blown away by some ideas that StackBlitz [0] apply based on WebContainers. The idea of a "server in the browser", they allow you to run Node-based environment like that via Wasm.

[0] https://stackblitz.com/

[1] https://webcontainers.io/

See https://webcontainers.io.

This very simple fact is well known flaw, which was already often criticized and asked for solutions by users. It doesn't only affect this kind of very exotic bootstrap applications but also significantly limits rusts usefulness in many other areas. Pure browser based scientific code documentation and example notebooks (e.g. jupyterLite) and sandboxed CI and IDE solutions (e.g. web containers) as available for many other languages are simply not available for rust because of this very fundamental issue.

Looks like they plan to open it. From the FAQ section of README (https://github.com/stackblitz/webcontainer-core#faqs):

> Is there a developer API?

I'm skeptical about stackblitz claims. The last time I checked that is closed source code https://github.com/stackblitz/webcontainer-core/issues/658.

StackBlitz claimed https://blog.stackblitz.com/posts/introducing-webcontainers/ to have implemented Node.js in the browser, though I have not observed any evidence of that being true and correct https://github.com/stackblitz/webcontainer-core/issues/658.

The other honorable mention is StackBlitz, a web-based web editor for making containers that run Javascript applications. Interestingly, StackBlitz is championing WebContainers, a technology that allows developers to start NodeJS servers within the browser. The downside is, this technology only works with Javascript-based projects (NodeJS, NextJS, etc). I include it here because WebContainers could easily be extended to support other languages via WASM, like Ruby. I’ll also add in Buildah, a tool for building OCI images. I won’t say much about this tool because it’s designed for building images; you still need another service, like Podman, to actually create the containers.

As far as I can tell, they aren't.

http://lua-users.org/wiki/SandBoxes

There is a lot of information there, but it doesn't handle resource exhaustion, execution time limits or give any guarantees. It does indicate that it's possible, and has a decent example of the most restrictive setup, which is a good start. But I would for example compare it with Luau's SECURITY.md.

From https://github.com/luau-lang/luau/blob/master/SECURITY.md:

> Luau provides a safe sandbox that scripts can not escape from, short of vulnerabilities in custom C functions exposed by the host. This includes the virtual machine and builtin libraries. Notably this currently does not include the work-in-progress native code generation facilities.

> Any source code can not result in memory safety errors or crashes during its compilation or execution. Violations of memory safety are considered vulnerabilities.

> Note that Luau does not provide termination guarantees - some code may exhaust CPU or RAM resources on the system during compilation or execution.

So, even luau will have trouble with untrusted code, but it specifies exactly what happens and so on. I think that's fair enough.

Alternatively, Luau is a well-supported Lua variant with type checking and performance improvements, aimed more towards being a sandboxed embedded scripting environment.

https://luau-lang.org/

If you need Lua but also type-safety, how about Luau [1] then?

[1] https://luau-lang.org/

I had the pleasure of working with Lua 5.1 back in the late noughties. For me it's replaced Tcl whenever I want something I can configure above a C library. At the time I used it I found it quite nice but I'll also not forget the hours I wasted tracking down nil table corruptions which could have easily been caught by a type checker.

I had some hope that Luau https://luau-lang.org or Teal https://github.com/teal-language/tl would make things better but with the following example

    function foo(x: number): string

Looking at other replies here, I can see I wasn't the only one who didn't realize there is Lua and Luau. Luau is an extension of Lua: https://luau-lang.org/

> Luau is syntactically backwards-compatible with Lua 5.1 (code that is valid Lua 5.1 is also valid Luau); however, we have extended the language with a set of syntactical features that make the language more familiar and ergonomic.

Lua is usually the embedded language of choice. If you are focused on security, you could check out the Roblox fork, Luau (https://github.com/Roblox/luau) where the creators took extra care to lock down the language on what scripts could do.

Luau - Lua variant by Roblox

On a side note, I've heard that they recently switched from Lua to Roblox's own fork of Lua, Luau.

https://www.youtube.com/results?search_query=luau+roblox&sp=...

Luau

https://github.com/Roblox/luau

Roblox wrote a superset of Roblox Lua which is way faster

https://luau-lang.org/ - some documentation, and examples https://create.roblox.com/docs - documentation, tutorials, and examples https://www.youtube.com/user/AlvinBLOX - tutorials https://www.youtube.com/@TheDevKing/videos - tutorials https://www.lua.org/manual/5.1/ - not specific to Roblox, but Lua reference manual https://www.codecademy.com/learn/learn-lua - Lua on Codecademy