Firecracker is a fine technology, but serverless companies have started taking advantage Wasm's faster start-up and invocation times for use cases of running Wasm on the server (https://www.youtube.com/watch?v=yqgCxhPAao0). The deny by default security policy makes Wasm a popular choice to run code in isolation, particularly for maximizing hardware resources in the multi-tenant environments these serverless companies operate.
> Is there a good reason to do this?
One use case to run JS inside a Wasm VM is Shopify Functions. Shopify allows their customers to customize things like checkout flow by writing code compiled to Wasm which gets executed during the checkout process. They want their customers to be able to write JS as well as other languages. https://github.com/Shopify/function-runner
> I thought WASM typically used the V8 JavaScript interpreter as its sandbox and to execute code.
V8 is popular for running Wasm on the web and for some serverless companies, but there are a bunch of serverless, blockchain, and iot projects that use other Wasm runtimes (Wasmtime, WAMR, WasmEdge, and Wasmer to name a few) - https://github.com/appcypher/awesome-wasm-runtimes
Great talk, thanks for sharing! Would love to hear if Extism allows you to accomplish this, and if not, what prevented you. We're always down to chat on Discord, but an issue on the Ruby SDK repo will do just fine as well - https://github.com/extism/ruby-sdk/
To help spread some knowledge and make WebAssembly more approachable, me and a couple of colleagues decided to do a write up on the concept of Command vs Reactor modules. We hope this saves someone the time and energy!
Thanks for the feedback, we've done some internal work to verify open source, self hosted platforms like Jaeger, Zipkin, and OpenObserve. Official support is coming soon!