Story

Hi everyone,

I built a runtime to isolate untrusted code using wasm sandboxes.

Basically, it protects your host system from problems that untrusted code can cause. We’ve had a great discussion about sandboxing in Python lately that elaborates a bit more on the problem [1]. In TypeScript, wasm integration is even more natural thanks to the close proximity between both ecosystems.

The core is built in Rust. On top of that, I use WASI 0.2 via wasmtime and the component model, along with custom SDKs that keep things as idiomatic as possible.

For example, in Python we have a simple decorator:

  from capsule import task

  @task(
      name="analyze_data", 
      compute="MEDIUM",
      ram="512mb",
      allowed_files=["./authorized-folder/"],
      timeout="30s", 
      max_retries=1
  )
  def analyze_data(dataset: list) -> dict:
      """Process data in an isolated, resource-controlled environment."""
      # Your code runs safely in a Wasm sandbox
      return {"processed": len(dataset), "status": "complete"}

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

  export const analyze = task({
      name: "analyzeData", 
      compute: "MEDIUM", 
      ram: "512mb",
      allowedFiles: ["./authorized-folder/"],
      timeout: 30000, 
      maxRetries: 1
  }, (dataset: number[]) => {
      return {processed: dataset.length, status: "complete"}
  });

It's still quite early, but I'd love feedback. I’ll be around to answer questions.

GitHub: https://github.com/mavdol/capsule

[1] https://news.ycombinator.com/item?id=46500510