Use bun for all front end concerns by wout · Pull Request #2015 · luckyframework/lucky

wout · 2026-02-15T18:03:27Z

Changes

This is just the current state of the Bun implementation as a first draft. This works locally in development in the Fluck website app, and all tests pass as expected.

Changes needed in the Lucky app itself are:

Procfile.dev

assets: bun run dev

package.json

  "scripts": {
    "build": "bun lib/lucky/src/bun/bake.js",
    "dev": "bun run build --dev",
    "prod": "bun run build --prod"
  },

src/components/shared/layout_head.cr

bun_reload_connect_tag

Other

Run bun run prod for deployment
Add the shared config/bun.json file (optional, all fallbacks are in place)

Questions

I'd like to add more tests but I'm a bit stuck. More specifically I'm a bit confused by the Lucky::AssetBuilder::Mix and Lucky::AssetBuilder::Vite classes. They only ever seem to be used in the test suite. What's their purpose? Are these preparations for the pluggable asset system?

What confuses me is that they are part of src but only used in spec. Of course I can add a Bun variant with a test suite, but I thought I'd ask first.

The central config file ensures both Bun and Lucky use the same output dir, manifest file, source dirs, etc.

The bake script handles all front-end asset needs. It builds and moves assets and generates a manifest. In development, it runs a watcher, starts a WebSocket-server, and creates unminified builds. In production it minifies and fingerprints all assets.

This test suite uses Bun's built in test helpers.

Also renames the original generate_asset_helper to match Bun's variant.

By default it now uses Bun. with the `legacy` flag, the old Mix manifest can be generated. The `css_entry_points` class method is used for the HMR script to dynamically reload CSS files without a full page reload. This commit also removes duplication in the dynamic_asset helpers.

This adds a development tag helper rendering a reload script that connects with Bun's WebSocket server. It performs hot reloads for changes to CSS files and full page reloads for any other assets.

Check if a source file exists and avoid processing if it does not, and log a warning reference.

Rather than writing Bun's manifest file to the assets dir, write it to the public dir as bun-manifest.json.

jwoertink · 2026-02-16T15:41:29Z

This is so awesome! And I love that you added some tests for the javascript stuff too. That'll be a huge help in maintaining it. Thanks for putting this all together. I feel like this pushes Lucky into some more much needed modern setup 🙌

As for the asset build system...

What's their purpose?

These were part of what I was talking about possibly reverting. This was added in order to make the asset system pluggable. I'm still not sure if I should revert them or not. The idea would be that you configure whichever build system you wanted to use, and then Lucky internally knows when to call the different commands it needs for each... However, I don't think it was ever completed because we got stuck on just trying to make Vite work out of the box.

On the one hand, it's basically useless code sitting around doing nothing so probably should be removed... On the other hand, we could actually just use it and then maybe the asset builder wouldn't need weird args like legacy: true or use_vite: true... though, I'm not sure if it would be possible to even configure at the macro level 🤔 I don't know, I'm a bit torn on it. I guess worst case is we remove it and just add it back later if we really want?

wout · 2026-02-16T16:44:00Z

Thanks! Bun feels really snappy and I love that it doesn't require any dependencies. Not even for the test suite.

A pluggable asset system is a great idea in itself I think, and adding the Bun counterparts wouldn't be a lot of work. But I'm not completely clear when it would be invoked. Would that be at compile time like the current AssetManifestBuilder? Because it would be great to modularise that part.

The only thing is that if it's kept around, the Vite implementation should be equally usable as the Mix and Bun versions. We could harvest the good parts from the LuckyVite shard which works, but is it worth the effort? It's not that any of us has the spare time to put in the effort into something that may not even be used at all 😄.

UPDATE:
For the flags on the load_manifest macro, we could rework that so it's less messy:

load_manifest(from: :bun) (default)
load_manifest(from: :vite)
load_manifest(from: :mix)

And then the frontend would require a bit of manual configuration which is inevitable I think.

wout · 2026-02-17T08:26:52Z

I don't know, I'm a bit torn on it. I guess worst case is we remove it and just add it back later if we really want?

My two cents on this. For now I think it may be better to park it. It's only once every five years you'd need to reconsider the asset build system, and I suppose you don't want to add support for every bundler available. Lucky has always been opinionated (PostgreSQL, LuckyHTML, Laravel Mix, etc.) and personally I don't feel that should change for the bundler.

It would be good to restructure the asset manifest builder a bit so that it's easier to add different manifest parsers, and switch between the build systems with a single argument on the load_manifest macro. But that's more about maintainability than pluggability.

wout · 2026-02-20T18:00:27Z

Is there something I can still do for the Bun implementation? Like reworking the asset manifest builder to make it switch between Mix/Vite/Bun? Or if you need more time to think about it, that's fine with me. I don't want to rush you.

This weekend I'll be mostly working on the Lucky::Attachment proposal, which is going well too. So plenty to do anyway 😄.

jwoertink · 2026-02-20T18:33:29Z

I like your suggestion of changing the load_manifest with from: :bun, etc... And I agree, there will still be some sort of manual configuration for the frontend, but as long as the backend gets out of your way to allow you to do that , then it should be good 👍

I see the title still has WIP, is this fully ready for review? I poked around real quick, but haven't had a free moment to really get my head in that space just yet. I plan on taking a look this weekend or next week at the latest though.

Thanks again for all this work. This is huge! 🙌

wout · 2026-02-20T18:55:09Z

Great, then I'll restructure the asset manifest builder as well to work with all bundlers.

And yes, this is still a WIP. Hopefully by the end of this weekend it will be ready for a first review round. I'll remove the WIP from the title and let you know when it's ready.

wout · 2026-02-22T18:41:54Z

@jwoertink I've reworked the asset manifest builder to handle all three bundlers and changed the signature on the load_manifest macro. I've kept the manifest_path argument as the first one for backwards compatibility.

The Bun implementation still works as expected, I've tested it locally with the Fluck website. The Mix and Vite implementations are harder to test because of the pluggable asset system. So I suppose that should be rolled back first to evaluate the situation. I also don't have any Lucky apps still using mix, so it's difficult to test a real-world app from my side.

UPDATE
I just replaced the Vite setup with the new Bun implementation on the Fluck app we're building (not the website) and the complete font-end build went from ±550ms to ±45ms for the same code. That's a 11x speed bump!

jwoertink

I'm not seeing anything glaring in any of this. I think it's all looking good. Super stoked to get this in, and that's way awesome you got such a nice performance boost. I have some mix and vite apps I can test this all against.

I'll get this merged in, and then work on ripping out that other stuff and make sure the CLI is all prepped. Thanks!!

wout · 2026-02-23T18:49:59Z

Fantastic! Let me know if you need any help with the CLI. You can always look here for setup pointers: https://codeberg.org/fluck/website. Although that repo has the code still embedded.

wout added 15 commits February 15, 2026 12:43

Add shared config between Lucky and Bun

3908c0a

The central config file ensures both Bun and Lucky use the same output dir, manifest file, source dirs, etc.

Add bake script for Bun

642a9dc

The bake script handles all front-end asset needs. It builds and moves assets and generates a manifest. In development, it runs a watcher, starts a WebSocket-server, and creates unminified builds. In production it minifies and fingerprints all assets.

Add a test suite for the bake script

27c4078

This test suite uses Bun's built in test helpers.

Add asset manifest builder for Bun

388470e

Also renames the original generate_asset_helper to match Bun's variant.

Rename Bun namespace to LuckyBun

8bede92

Add bun reload tag

20a3e99

This adds a development tag helper rendering a reload script that connects with Bun's WebSocket server. It performs hot reloads for changes to CSS files and full page reloads for any other assets.

Install Bun in Dockerfile for tests

9eb7dfc

Run Bun test suite alongside Lucky's

f481052

Remove unnecessary global dynamic asset helper

562f843

Add example Bun manifest

8baf688

Make sure build does not fwil with missing source

8e75810

Check if a source file exists and avoid processing if it does not, and log a warning reference.

Use legacy flag to load manifest

39800b7

Follow Lucky's convention with manifest files

746fb48

Rather than writing Bun's manifest file to the assets dir, write it to the public dir as bun-manifest.json.

Load Bun manifest in test suite

7c83470

wout mentioned this pull request Feb 15, 2026

Vite auto-reload (HMR?) luckyframework/lucky_cli#913

Open

Use full module name to access asset manifest

bd709e1

wout added 2 commits February 22, 2026 19:17

Combine asset anifes builders for all bundlers

814d196

Fix manifest and bundler args in load_manifest macro

02696fa

wout changed the title ~~WIP: Use bun for all front end concerns~~ Use bun for all front end concerns Feb 22, 2026

Add comments to asset manifest builder and helpers

79266bc

jwoertink approved these changes Feb 23, 2026

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Use bun for all front end concerns#2015

Use bun for all front end concerns#2015
wout wants to merge 19 commits intoluckyframework:mainfrom
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