webpack / webpack/webpack-dev-server

Breaking change in patch version breaks Module Federation cross-origin development (semver violation)

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Dominant language
JavaScript
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Description

Setup:
Module Federation development pattern:

  • Host app on localhost:8000
  • Exposed app on localhost:8001

Error:
Error: [ Federation Runtime ]: Failed to load script resources. #RUNTIME-008
at http://localhost:8000/ trying to load http://localhost:8001/remoteEntry.js

Problem:
A breaking change was added in https://github.com/webpack/webpack-dev-server/commit/df073c5
(Cross-Origin-Resource-Policy: same-origin header) in a patch version.

This common, working development setup now silently fails unless Access-Control-Allow-Origin header is explicitly added.

  • Before patch: worked without CORS configuration
  • After patch: breaks silently

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the two-app setup with the host at localhost:8000 and the exposed app at localhost:8001, then inspect commit df073c5 and its Cross-Origin-Resource-Policy change. Verify the behavior around loading remoteEntry.js and define done as restoring or clearly addressing this cross-origin development setup without the reported silent failure.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript
Domain
devtools, web-dev
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
45/100

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