deno-esbuild: Deno Deploy support

[ayoreis]

Deno Deploy is an edge runtime by Deno. And it would be awesome to use esbuild with it, but when I try to run this code:

import * as esbuild from "https://deno.land/x/esbuild@v0.14.45/mod.js";
const ts = 'let test: boolean = true'
const result = await esbuild.transform(ts, { loader: 'ts' })
console.log('result:', result)
esbuild.stop()

It gives me this error:

Error: Failed to find cache directory
    at getCachePath (https://deno.land/x/esbuild@v0.14.45/mod.js:1759:11)
    at installFromNPM (https://deno.land/x/esbuild@v0.14.45/mod.js:1713:35)
    at install (https://deno.land/x/esbuild@v0.14.45/mod.js:1802:18)
    at https://deno.land/x/esbuild@v0.14.45/mod.js:1813:29
    at ensureServiceIsRunning (https://deno.land/x/esbuild@v0.14.45/mod.js:1941:7)
    at Module.transform (https://deno.land/x/esbuild@v0.14.45/mod.js:1679:37)
    at file:///src/main.tsx:8:30

I don't get the error right now, but I can try to find the problem and then propose a fix.

[evanw]

You can read the source code here:

esbuild/lib/deno/mod.ts

Lines 83 to 117 in 20f4b45

	function getCachePath(name: string): { finalPath: string, finalDir: string } {
	let baseDir: string | undefined
	switch (Deno.build.os) {
	case 'darwin':
	baseDir = Deno.env.get('HOME')
	if (baseDir) baseDir += '/Library/Caches'
	break
	case 'windows':
	baseDir = Deno.env.get('LOCALAPPDATA')
	if (!baseDir) {
	baseDir = Deno.env.get('USERPROFILE')
	if (baseDir) baseDir += '/AppData/Local'
	}
	if (baseDir) baseDir += '/Cache'
	break
	case 'linux':
	// https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
	const xdg = Deno.env.get('XDG_CACHE_HOME')
	if (xdg && xdg[0] === '/') baseDir = xdg
	break
	}
	if (!baseDir) {
	baseDir = Deno.env.get('HOME')
	if (baseDir) baseDir += '/.cache'
	}
	if (!baseDir) throw new Error('Failed to find cache directory')
	const finalDir = baseDir + `/esbuild/bin`
	const finalPath = finalDir + `/${name}@${version}`
	return { finalPath, finalDir }
	}

This will fail on Linux if certain environment variables aren't set. I don't use Deno and know nothing about it so I can't help you, sorry.

[ayoreis]

Thanks for your reply @evanw ❤️. I'll look into this soon.

[evanw]

BTW if you are ok with using WebAssembly instead of native, then you can try that when the next version of esbuild is released soon. See #2323 which was just fixed.

[evanw]

Marking as unactionable until more information is provided.

[ayoreis]

Update: Deno Deploy does not support Deno.writeFile nor Deno.run (at least yet). That's what's causing the errors, the best option right now is using WebAssembly as you sugested, though its not enough for my use case where I need building.

So my proposal is that we make build available in the WebAssembly version and get files with fetch(new URL('./path/to.file')).text() / the user being required to write a plugin that would resolve all the files by itself.

This would allow building in Deno Deploy 🦕, and in the browser 🌐! You mentioned in #2323 that to get this working it would require additional work, so I am not expecting this to happen and just proposing it. Maybe I could even learn Go and do it myself.

And maybe esbuild switching automatically to WebAssembly in Deno Deploy, but I don't think that's necessary since you can just check for the existence of Deno.run and fallback to WebAssembly.

What do you think? Do I write a new issue for this?

[evanw]

I'm confused. The build API already works. Here's an example:

import * as esbuild from 'https://deno.land/x/esbuild@v0.14.48/wasm.js'
const result = await esbuild.build({
  stdin: {
    contents: `
      import x from 'fib(10)'
      console.log('fib(10) is', x)
    `,
  },
  bundle: true,
  plugins: [{
    name: 'some-plugin',
    setup(build) {
      build.onResolve({ filter: /^fib\((\d+)\)/ }, args => {
        return { path: args.path, namespace: 'fib' }
      })
      build.onLoad({ filter: /^fib\((\d+)\)/, namespace: 'fib' }, args => {
        let match = /^fib\((\d+)\)/.exec(args.path), n = +match[1]
        let contents = n < 2 ? `export default ${n}` : `
          import n1 from 'fib(${n - 1}) ${args.path}'
          import n2 from 'fib(${n - 2}) ${args.path}'
          export default n1 + n2`
        return { contents }
      })
    },
  }],
})
eval(result.outputFiles[0].text)
Deno.exit(0)

That should print this:

fib(10) is 55

You'll need to use an esbuild plugin to avoid the file system if Deno Deploy doesn't have a file system, but there should be nothing preventing you from using esbuild in that case. I'm not planning on testing esbuild with Deno Deploy myself because it's a closed service so it'll be up to you to figure out how to write the plugin you need for this. I'm closing this issue since esbuild's current WebAssembly implementation should be sufficient for this.