Stream: wasi

Topic: Extend an existing wasm32-unknown-unknown module with http

Manu Schiller (Apr 23 2023 at 13:16):

Hi,
After KubeCon I got to fiddle around with the decision engine OPA. It is available as go binary and as wasm32-unknown-unknown wasm module. The Go binary offers the capability to send http requests via http.send.

In the wasm module the capability is not implemented.
The wasm module can be extended by host functions (https://github.com/open-policy-agent/npm-opa-wasm/blob/main/test/opa-custom-builtins.test.js#L47), but right now it is impossible to have async functions like Javascript Promises.

If I got the wasm component model right, it should be possible to:

• create a wasm module that uses wasi to request arbitrary urls
• and that exposes this capability to the original opa wasm module

Is that on a high level correct?

Bailey Hayes (Apr 24 2023 at 15:52):

For async behavior, the typical solution is to have host functions implemented with callbacks.

Longer term, I'd expect OPA to support wasi and the outgoing-handler interface of wasi-http.

Last updated: Dec 23 2024 at 12:05 UTC