Build with WebWorkers seems broken

[ogonkov]

Describe the bug

I'm tried to get MF to work with WebWorkers, but got exception

TypeError: can't access property "remotes", __webpack_require__.federation.bundlerRuntime is undefined

Reproduction

https://github.com/ogonkov/module-federation-examples/tree/chore/worker_problem/worker-with-dynamic-import

Used Package Manager

pnpm

System Info

System:
    OS: macOS 15.6.1
    CPU: (12) arm64 Apple M3 Pro
    Memory: 4.30 GB / 36.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.19.2 - ~/.nvm/versions/node/v20.19.2/bin/node
    Yarn: 1.22.22 - ~/.nvm/versions/node/v20.19.2/bin/yarn
    npm: 10.8.2 - ~/.nvm/versions/node/v20.19.2/bin/npm
    pnpm: 10.14.0 - ~/.nvm/versions/node/v20.19.2/bin/pnpm
  Browsers:
    Chrome: 140.0.7339.133
    Safari: 18.6

Validations

• Read the docs.
• Read the common issues list.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Module federation issue and not a framework-specific issue.
• The provided reproduction is a minimal reproducible example of the bug.

[2heal1]

Hmm.. This indeed exist, let me try to fix it .

[2heal1]

It's a bit complex to fix completely. But i find a workaround .

1. Set workerOptions.name
2. Add worker entry in build config with the workerOptions.name

// set workerOptions.name
const fibWorker = new Worker(new URL('../fib-worker.js', import.meta.url), {
  name: 'worker',
  type: 'module',
});

// add entry by manually

webpack/rspack.config 

{
  entry: {
     ...prevEntry,
     worker: WORKER_PATH
  }
}

MF will inject MF runtime into entries, but the worker only create asyncBlock in parser period which MF can not inject mf runtime , and finally cause the .f.remotes not undefined issue .

If we declare the entry at build config , mf will inject runtime as expected .

This is a temp workaround, I will try to optimize current mf runtime inject method to fix it in the future,

[ogonkov]

I need to add path to every worker as entry in config?

[ogonkov]

Interesting, error is gone, but worker code itself is like don't executed, no console log from module loading, i use Comlink, may be it is something on their side, i will investigate more

[2heal1]

I need to add path to every worker as entry in config?

Yes, that's a bit ugly, but can work .

[ogonkov]

Somehow adding entry breaks modernjs build completely, i will try to convert this example to webpack-config