Using WebAssembly Modules from IBM Cloud Functions (Apache OpenWhisk)

README.md

$ emcc -s WASM=1 -s SIDE_MODULE=1 -s EXPORTED_FUNCTIONS="['_add']" -O1 add.c -o add.wasm
$ zip action.zip index.js add.wasm package.json
updating: index.js (deflated 52%)
updating: add.wasm (deflated 7%)
updating: package.json (deflated 15%)
$ ibmcloud wsk action create wasm action.zip --kind nodejs:10
ok: created action wasm
$ ibmcloud wsk action invoke wasm -r -p a 2 -p b 2
{
    "sum": 4
}

add.c

int add(int a, int b) {
  return a + b;
}

index.js

'use strict';
const fs = require('fs');
const util = require('util')

const WASM_MODULE = 'add.wasm'
let wasm_instance 

async function load_wasm(wasm_module) {
  if (!wasm_instance) {
    const bytes = fs.readFileSync(wasm_module);
    const memory = new WebAssembly.Memory({initial: 1});
    const env = {
      __memory_base: 0,
      memory: new WebAssembly.Memory({
        initial: 1
      })
    }

    const { instance, module } = await WebAssembly.instantiate(bytes, { env });
    wasm_instance = instance
  }

  return wasm_instance.exports._add
}

exports.main = async function ({ a = 1, b = 1 }) {
  const add = await load_wasm(WASM_MODULE)
  const sum = add(a, b)
  return { sum }
}

package.json

{
  "name": "wasm",
  "version": "1.0.0",
  "main": "index.js"
}