fix(enhanced): Add fallback parsing for container module exposes #4034

vinicius-at-webflow · 2025-09-01T19:34:58Z

Description

The _handleContainerModule method from packages/manifest/src/ModuleHandler.ts calls split(' ') on the module's identifier which breaks if the path or expose key contain spaces or other special characters.

Here's a an example of a problematic identifier (see the import path for the Button expose):

container entry (default) [["./Button",{"import":["./src/path with spaces/Button.tsx"],"name": "__federation_expose_Button"}]]

Related Issue

#2684

Types of changes

Docs change / refactoring / dependency upgrade
Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)

Checklist

I have added tests to cover my changes.
All new and existing tests passed.
I have updated the documentation.

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vinicius-at-webflow · 2025-09-01T19:36:38Z

Opened previous PR with main as source branch 😓. Sorry for the inconvenience!

vinicius-at-webflow · 2025-09-01T19:37:20Z

packages/manifest/src/ModuleHandler.ts

+    let entries: Array<
+      [exposeKey: string, { import: string[]; name?: string }]
+    > = [];
+
+    try {
+      // Prefer parsing exposes from stats first
+      entries = JSON.parse(data[3]);
+    } catch {
+      // If that fails, fallback to the original options
+      const exposes = this._options.exposes;
+
+      if (!exposes || typeof exposes !== 'object') {
+        return;
+      }
+
+      entries = Object.entries(exposes);
+    }
+
+    entries.forEach(([prefixedName, file]) => {


I'm opting to maintain the current JSON parsing logic and wrap it in a try catch block. There are probably good reason why it was implemented this way in the first place, but I lack the context, and I rather be as safe/backwards compatible as possible. If it fails the introduced logic just attempts to recover exposes from another source.

@2heal1 @ScriptedAlchemy As you mentioned in the issue, there are probably better ways of solving this, but again, I lack the context to propose a long-term solution. You mentioned a short-term solution, but since the issue was closed, I figured it wouldn't hurt proposing this patch 😅.

Also note I'm open to contribute and implement this in a different way if I can get some high level guidance (Just a couple of quick notes would be really helpful).

vinicius-at-webflow · 2025-09-01T19:37:35Z

packages/enhanced/test/configCases/build-version/package-json-version/webpack.config.js

@@ -18,6 +18,7 @@ module.exports = {
      library: { type: 'commonjs-module' },
      filename: 'remoteEntry.js',
      exposes: {
+        './a test module': './test.js',


This does break without the patch. Would this be enough test coverage?

But this is not expected expose key, will this issue only happen in this scene ?

@2heal1 Oh, you're absolutely right. But it does break if the spaces are present on the path, say:

{ exposes: { './test': './path with spaces/test.js' } }

I just wanted to modify the test as little as possible, but I can tweak it to represent an actual real scenario!

vinicius-at-webflow · 2025-09-01T19:38:26Z

packages/manifest/src/ModuleHandler.ts

+      // If that fails, fallback to the original options
+      const exposes = this._options.exposes;
+
+      if (!exposes || typeof exposes !== 'object') {


#4027 (comment)

From my investigations this.options.exposes in ModuleHandler is always parsed into

interface ExposesObject { [k: string]: ExposesConfig; } interface ExposesConfig { import: ExposesItem | ExposesItems; name?: string; }

by ContainerManager.containerPluginExposesOptions. But due to how everything is currently typed, TS thinks this could be the broader "unparsed" Exposes shape.

type Exposes = (ExposesItem | ExposesObject)[] | ExposesObject;

This is how it looks like, for both enhanced/ModuleFederationPlugin and rspack/ModuleFederationPlugin

Now, we could maintain this 100% decoupled and idempotently "re-parse" the entries ModuleHandler to ensure the type safety, but I would wait for a review first before increasing the complexity here. cc @ScriptedAlchemy @2heal1

2heal1 · 2025-09-05T03:04:25Z

Does the issue only happen in legacy version ? I want to know which version , if old enough, maybe no need to compate it .

Can you provide a minimal reproduce repo ? So i can get more info .

vinicius-at-webflow · 2025-09-05T13:45:50Z

@2heal1 No, it happens on any version, even the latest. Its probably under the radar (although there is an issue open #2684) because it is very unusual to have spaces in paths in "conventional" codebases 😆.

But in our use case of Module Federation, we have no control over what the project folder structure looks like (and in fact we have run into the issue more than once), so this is why I'm proposing this fix!

Here's the repro, just npm install; npm run build:

https://github.com/vinicius-at-webflow/mf-path-issues

You should see

[webpack-cli] HookWebpackError: Unterminated string in JSON at position 120
  SyntaxError: Unterminated string in JSON at position 120
    at JSON.parse (<anonymous>)
    at ModuleHandler._handleContainerModule

because of "./test-2": "./src/path with spaces/test-2.js",

vinicius-at-webflow · 2025-09-05T13:49:38Z

I can probably add an integration test using this repo I sent you, to avoid any confusion around what this is fixing, exactly, so I guess a test would make everything more clear.

…ated edge case test

vinicius-at-webflow · 2025-09-06T17:53:14Z

@2heal1 I added a dedicated test case to validate the fix. If you uncomment you should see the same

Unterminated string in JSON at position 31; stack = HookWebpackError: Unterminated string in JSON at position 31
    at JSON.parse (<anonymous>)
    at ModuleHandler._handleContainerModule

as the user reports in the issue, as well as in the minimal repro I shared with you

vinicius-at-webflow · 2025-09-11T18:41:32Z

@2heal1 bump

ScriptedAlchemy · 2025-09-14T19:13:59Z

@codex review

chatgpt-codex-connector · 2025-09-14T19:19:31Z

Codex Review: Didn't find any major issues. Hooray!

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vinicius-at-webflow added 3 commits August 28, 2025 18:22

fix(enhanced): add fallback parsing for container module exposes

aef90ed

fix(enhanced): add fallback parsing for container module exposes

68ebd01

Merge branch 'main' into main

2955c59

github-actions bot added the change: fix label Sep 1, 2025

vinicius-at-webflow commented Sep 1, 2025

View reviewed changes

vinicius-at-webflow marked this pull request as ready for review September 1, 2025 19:40

vinicius-at-webflow added 3 commits September 6, 2025 14:15

Merge branch 'main' into fix-handle-container-module

ba44e59

chore: remove changes to package-json-version tests and include dedic…

ef84efd

…ated edge case test

test: provide public path

b55085a

vinicius-at-webflow requested a review from 2heal1 September 6, 2025 17:54

Merge branch 'main' into fix-handle-container-module

94d354c

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vinicius-at-webflow commented Sep 1, 2025

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2heal1 commented Sep 5, 2025

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vinicius-at-webflow commented Sep 11, 2025

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