vite-plugin-golang-wasm

What's this?

An opinionated vite plugin to load and run Go code as WASM, based on Golang-WASM's implementation.

Compatible for:

• vite@^4.0.0,
• rollup@^3.0.0,
• Go with GO111MODULE=on (recommended to use 1.17 or higher),
• and Node LTS (equivalent to node18 or higher, based on @tsconfig/node-lts/tsconfig.json).

Motivation

While I was looking up for a library to load Go code in my private project, I came across Golang-WASM project, which is exactly what I'm looking for (shoutout to teamortix for their great work!). Unfortunately, they have only implemented a loader for webpack environment, and I couldn't find any alternative implementations for vite or rollup environment. Hence, why I created this plugin.

Usage

For detailed information regarding the architecture of the bridge and bindings, please refer to Golang-WASM#JS Interop and Golang-WASM#How it works.

For plugin usage, simply import and register it to vite config just like most plugins:

// ./vite.config.ts
import { defineConfig } from 'vite'
import { qwikVite } from '@builder.io/qwik/optimizer'
import goWasm from 'vite-plugin-golang-wasm'

// https://vitejs.dev/config/
export default defineConfig({
  plugins: [
    goWasm(),
    qwikVite({
      csr: true,
    }),
  ],
})

⚠️ ATTENTION: Entrypoint's package must be main or it will fail to load. See go/wiki/WebAssembly, https://github.com/golang/go/issues/35657#issuecomment-554904779.

Create a Go code, for example, a math code:

//./src/math/math.go
package main

import (
	"errors"

	"github.com/teamortix/golang-wasm/wasm"
)

func add(x int, y int) (int, error) {
	return x + y, nil
}

func main() {
	wasm.Expose("add", add)
	wasm.Ready()
	<-make(chan struct{}, 0)
}

Then, import it from anywhere in source code:

// ./src/app.tsx
import { component$, useSignal } from '@builder.io/qwik'
// ...
import math from './math/math.go'

export const App = component$(() => {
  const count = useSignal(0)

  return (
    <>
      // ...
      <h1>Vite + Qwik</h1>
      <div class="card">
        <button
          onClick$={async () => {
            count.value = await math.add(count.value, 10)
          }}
        >
          count is {count.value}
        </button>
      </div>
      // ...
    </>
  )
})

Typescript Support

It's actually possible to generate typescript definition from Go source code since the official Go repository already offered set of tools to work with Go source code such as parser, scanner, AST types, etc. However, I don't think I have the time to actually implement that, given the size and scope of the feature.

Instead, each module needs to be defined via a Typescript's declaration file. Reusing math example from above, we can create declaration file for ./math/math.go file, like this:

// ./math/math.go.d.ts
const __default: {
  add: (x: number, y: number) => Promise<number>
}

export default __default

How it works

Essentially, this plugin will transform each "imported" Go file into JS code which only contains codes for loading WASM, while the actual Go codes are bundled or inlined.

Here is an example of math code above transformed into a simple WASM loader:

import '/@id/__x00__virtual:wasm_exec'
import goWasm from '/@id/__x00__virtual:wasm_bridge'

const wasm = fetch('data:application/wasm;base64,...').then((r) =>
  r.arrayBuffer()
)
export default goWasm(wasm)

While the actual code are transformed into WASM and bundled (in build mode) or inlined (in serve mode).

In build mode, the compiled Go is emitted as asset, returning the reference ID. The reference ID will be used in URI of the fetch to load it:

const wasm = fetch(import.meta.ROLLUP_FILE_URL_{REFERENCE_ID}).then(r=>r.arrayBuffer());

While in serve mode, the code is inlined to the fetch instead:

const wasm = fetch(`data:application/wasm;base64,{BASE_64_ENCODED_CODE}`).then(
  (r) => r.arrayBuffer()
)

The loader depends on implementation of Golang-WASM both on their JS interop and Golang WASM package.

Configuration

https://github.com/slainless/vite-plugin-golang-wasm/blob/8afe0a48ac9dc1bb4b4b043576231c86ceacc1fa/src/interface.ts#L3-L11

goBinaryPath, wasmExecPath

By default, goBinaryPath and wasmExecPath will be resolved relative to process.env.GOROOT if either of these options are not defined. But an error will be thrown when GOROOT is also not set. GOROOT needs to be added into OS's environment variables or set locally before running any script, for example GOROOT=/usr/bin/go vite dev. Alternatively, both these options can be provided to allow direct or custom go binary or wasm_exec.js resolving.

export default defineConfig({
  plugins: [
    goWasm({
      goBinaryPath: '/path/to/go/bin/go',
      wasmExecPath: '/path/to/go/misc/wasm/wasm_exec.js',
    }),
    qwikVite({
      csr: true,
    }),
  ],
})

Must be noted, however, that it's not recommended to point goBinaryPath to other compiler with very distinct CLI usage. Specifically, the compiler must accept or support this CLI execution:

`${binary} build ${optional_extra_args} -o ${output_path} ${input_path}`

For example, you can use tinygo compiler instead, by pointing goBinaryPath to tinygo path. Other extra argument such as --target can be added via goBuildExtraArgs.

goBuildDir, buildGoFile

goBuildDir will be resolved to os.tmpdir/go-wasm-${RANDOM_STRING}. This option defines the directory where the output and cache of the build should be placed. By default, it will create a temporary directory that persist throughout the lifecycle of vite process and will be cleaned up when process exits (either by SIGINT, normal exit, error, etc.). However, when this option is provided, it's assumed that end user will be responsible for managing the directory, from it's creation to it's cleanup.

buildGoFile is called when the code needs to be built. Default implementation:

https://github.com/slainless/vite-plugin-golang-wasm/blob/f48063ef18a79ec364244c87404cbf50c224ce16/src/build.ts#L5-L42

This option can be used to set custom build directive when more control is needed.

goBuildExtraArgs

goBuildExtraArgs allows you to add extra arguments and/or flags to the build call. For example, if your go codebase is in a subdirectory and you need to indicate to the compiler where is the go.mod file, you can provide extra -C flag to the build call:

export default defineConfig({
  plugins: [
    goWasm({
      goBuildExtraArgs: ["-C", "./path/to/go.mod/directory"]
    }),
    qwikVite({
      csr: true,
    }),
  ],
})

Dependencies

• exit-hook for catch-all solution to cleanup code, used to remove temporary directory: https://github.com/slainless/vite-plugin-golang-wasm/blob/8afe0a48ac9dc1bb4b4b043576231c86ceacc1fa/src/temp_dir.ts#L26-L28

To-Do

• [ ] Implement AST analysis for go code dependency for use in Vite HMR
• [ ] Implement handleHotUpdate to allow seamless HMR instead of page reload
• [ ] Add unit test

License

MIT

Created by slainless