WASI

The wasi adapter runs prebuilt .wasm modules in the browser. PocketStack does not compile source, run Docker builds, or manufacture a WASI module from a container image — point it at an already-built module.

How it's selected

Set pocketstack.adapter=wasi and provide the module (and optional argv) through the pocketstack.wasi.* labels.

services:
  tool:
    image: scratch
    labels:
      pocketstack.adapter: wasi
      pocketstack.wasi.module: hello.wasm
      pocketstack.wasi.args: "--name PocketStack"

See the labels reference for accepted values.

What it runs

The generated demo first tries built-in browser WASI preview1 imports for common preview1 modules. If the module needs fuller WASI/WASIX behavior, it falls back to Wasmer JS with the same argv and Compose environment values.

argv (from pocketstack.wasi.args) and environment values are passed through to the module.

WARNING

Prebuilt modules only. There is no source compilation or build step. If a project can compile cleanly to WASI, do that in your build pipeline and point PocketStack at the result.

Cross-origin isolation

The Wasmer JS fallback requires cross-origin isolation (COOP/COEP) headers and public CDN access. It still does not use a PocketStack backend. See hosting & headers for how to serve the required headers.