fix(sdk-trace-base): avoid webpack CommonJS self-reference

[sansynx]

Summary

• retain local bindings for the sdk-trace-base default span-attribute limits before exporting them
• add a Node/Webpack production regression fixture for the public NodeSDK CommonJS entry
• document the fix in the stable changelog

Root cause

TypeScript emitted internal reads of exported constants as exports.*. When Webpack tree-shook an ESM named import resolved through the CommonJS main entry, it treated that as an invalid self-reference.

Validation

• npm exec -- tsc --build packages/opentelemetry-sdk-trace-base/tsconfig.json --pretty false
• npm --prefix packages/opentelemetry-sdk-trace-base run lint
• npm exec -- mocha @testFiles (21 passing focused trace-base tests)
• node test-bundle.mjs in bundler-tests/node/webpack-5
• npm exec -- prettier --check ...
• npm exec -- markdownlint-cli2 CHANGELOG.md

Fixes #6981

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The committers listed above are authorized under a signed CLA.

• ✅ login: sansynx / name: sanath (4f68e1f)

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[Copilot]

Pull request overview

This PR addresses a webpack production bundling crash triggered when an ESM named import is resolved through a CommonJS main entry, by ensuring sdk-trace-base reads span-limit defaults from local bindings (avoiding exports.* self-references after TypeScript emit and webpack tree-shaking). It also adds a bundler regression fixture and documents the change.

Changes:

• Refactors sdk-trace-base default span-limit constants to retain local bindings before exporting.
• Updates the Node/webpack-5 bundler fixture to resolve via main (CommonJS) and exercises @opentelemetry/sdk-node’s public NodeSDK entry.
• Adds an Unreleased changelog entry for the fix.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/opentelemetry-sdk-trace-base/src/utility.ts	Keeps default limit constants as local bindings and exports them, preventing webpack self-reference failures.
bundler-tests/node/webpack-5/webpack.config.mjs	Forces resolve.mainFields: ['main'] to reproduce CommonJS-entry bundling behavior in production mode.
bundler-tests/node/webpack-5/src/index.js	Imports and instantiates NodeSDK from the public entry to cover the reported regression scenario.
bundler-tests/node/webpack-5/package.json	Adds the local @opentelemetry/sdk-node dependency for the new bundling fixture.
CHANGELOG.md	Documents the fix in the Unreleased bug fixes section.

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Waiting on reviewers · refreshed 2026-08-21 22:12 UTC

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[overbalance]

I recommend creating a new test suite instead of changing this one so the old bundling behavior is still covered.

[sansynx]

@overbalance Thanks for the suggestion, I split the NodeSDK/CommonJS regression into a new bundler-tests/node/webpack-5-sdk-node suite in 05b7b76 and restored bundler-tests/node/webpack-5 to its previous coverage

Both suites pass independently

[iivvaannxx]

Hi @overbalance @sansynx, is there an ETA for getting this merged? I have several consumers of a library I own facing the build error caused by the issue when using Webpack. Thanks!

[sansynx]

@iivvaannxx it's ready, just need @overbalance approval for this to get merged!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.09%. Comparing base (7f3e7ea) to head (05b7b76).
⚠️ Report is 22 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6982   +/-   ##
=======================================
  Coverage   95.09%   95.09%           
=======================================
  Files         409      409           
  Lines       14259    14260    +1     
  Branches     3269     3269           
=======================================
+ Hits        13559    13560    +1     
  Misses        700      700           

Files with missing lines	Coverage Δ
...ckages/opentelemetry-sdk-trace-base/src/utility.ts	100.00% <100.00%> (ø)

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[overbalance]

That's not entirely true 🙂 I'm a Browser maintainer so I check code that affects the client. A JS core approver still needs to look.

If you would, please add a brief comment above these constants explaining the declaration/export split is intentional. Like "TS gen CJS emit rewrites internal reads of export const to exports.*, which trips webpack’s self-reference handling when the export is tree-shaken unused (#6981, webpack/webpack#21619)

And thank you for pointing this out. I suspect the project has more instances of the same issue that will need investigation.

[overbalance]

Please update the link to match the others.

[sansynx]

Thanks for pointing that out — I’ve updated the entry to use the same linked issue format as the surrounding changelog items: #6981

[sansynx]

Thanks for the follow-up — I’ve added a short note above the constants explaining why they stay local and are exported separately

I also kept the sdk-node regression coverage in its own webpack suite, so the existing bundling behavior remains covered

The focused trace-base tests pass (22 tests), along with the trace-base compile, lint and formatting checks, changelog markdown lint, and the new Node/Webpack 5 bundle check

I used an AI coding assistant to help with the edit, then reviewed the diff and ran the checks myself