node/COLLABORATOR_GUIDE.md

Node.js Collaborator Guide

Contents

• Issues and Pull Requests
  • Managing Issues and Pull Requests
  • Welcoming First-Time Contributors
  • Closing Issues and Pull Requests
  • Author ready pull requests
  • Handling own pull requests
• Accepting Modifications
  • Code Reviews
  • Consensus Seeking
  • Waiting for Approvals
  • Testing and CI
    • Useful CI Jobs
  • Internal vs. Public API
  • Breaking Changes
    • Breaking Changes and Deprecations
    • Breaking Changes to Internal Elements
    • When Breaking Changes Actually Break Things
      • Reverting commits
  • Introducing New Modules
  • Additions to N-API
  • Deprecations
  • Involving the TSC
• Landing Pull Requests
  • Using git-node
  • Technical HOWTO
  • Troubleshooting
  • I Made a Mistake
  • Long Term Support
    • What is LTS?
    • How does LTS work?
    • Landing semver-minor commits in LTS
    • How are LTS Branches Managed?
    • How can I help?
    • How is an LTS release cut?
• Who to CC in the issue tracker

This document explains how Collaborators manage the Node.js project. Collaborators should understand the guidelines for new contributors and the project governance model.

Issues and Pull Requests

Managing Issues and Pull Requests

Collaborators should take full responsibility for managing issues and pull requests they feel qualified to handle. Make sure this is done while being mindful of these guidelines, the opinions of other Collaborators, and guidance of the TSC. They may also notify other qualified parties for more input on an issue or a pull request. See Who to CC in the issue tracker.

Welcoming First-Time Contributors

Courtesy should always be shown to individuals submitting issues and pull requests to the Node.js project. Be welcoming to first-time contributors, identified by the GitHub badge.

For first-time contributors, check if the commit author is the same as the pull request author, and ask if they have configured their git username and email to their liking. This is to make sure they would be promoted to "contributor" once their pull request lands.

Closing Issues and Pull Requests

Collaborators may close any issue or pull request they believe is not relevant for the future of the Node.js project. Where this is unclear, the issue should be left open for several days to allow for additional discussion. Where this does not yield input from Node.js Collaborators or additional evidence that the issue has relevance, the issue may be closed. Remember that issues can always be re-opened if necessary.

Author ready pull requests

A pull request that is still awaiting the minimum review time is considered author ready as soon as the CI has been started, it has at least two approvals (one Collaborator approval is enough if the pull request has been open for more than 7 days), and it has no outstanding review comments. Please always make sure to add the author ready label to the PR in that case and remove it again as soon as that condition is not met anymore.

Handling own pull requests

When you open a pull request, it is recommended to start a CI right away (see testing and CI for instructions) and to post the link to it in a comment in the pull request. Starting a new CI after each update is also recommended (for example, after an additional code change or after rebasing).

As soon as the PR is ready to land, please do so. Landing your own pull requests allows other Collaborators to focus on other pull requests. If your pull request is still awaiting the minimum time to land, add the author ready label so other Collaborators know it can land as soon as the time ends. If instead you wish to land the PR yourself, indicate this intent by using the "assign yourself" button, to self-assign the PR.

Accepting Modifications

All modifications to the Node.js code and documentation should be performed via GitHub pull requests, including modifications by Collaborators and TSC members. A pull request must be reviewed, and must also be tested with CI, before being landed into the codebase. There may be exceptions to the latter (the changed code cannot be tested with a CI or similar). If that is the case, please leave a comment that explains why the PR does not require a CI run.

Code Reviews

At least two Collaborators must approve a pull request before the pull request lands. (One Collaborator approval is enough if the pull request has been open for more than 7 days.) Approving a pull request indicates that the Collaborator accepts responsibility for the change. Approval must be from Collaborators who are not authors of the change.

In some cases, it may be necessary to summon a GitHub team to a pull request for review by @-mention. See Who to CC in the issue tracker.

If you are unsure about the modification and are not prepared to take full responsibility for the change, defer to another Collaborator.

If you are the first Collaborator to approve a pull request that has no CI yet, please start one (see testing and CI for further information on how to do that) and post the link to the CI in the PR. Please also start a new CI in case the PR creator pushed new code since the last CI run (due to e.g., an addressed review comment or a rebase).

In case there are already enough approvals (LGTM), a CI run, and the PR is open longer than the minimum waiting time without any open comments, please do not (only) add another approval. Instead go ahead and land the PR after checking the CI outcome.

Consensus Seeking

If there are no objecting Collaborators, a pull request may land if it has the needed approvals, CI, and wait time. If a pull request meets all requirements except the wait time, please add the author ready label.

Where there is disagreement among Collaborators, consensus should be sought if possible. If reaching consensus is not possible, a Collaborator may escalate the issue to the TSC.

Collaborators should not block a pull request without providing a reason. Another Collaborator may ask an objecting Collaborator to explain their objection. If the objector is unresponsive, another Collaborator may dismiss the objection.

Breaking changes must receive TSC review. If two TSC members approve the pull request and no Collaborators object, then it may land. If there are objections, a Collaborator may apply the tsc-agenda label. That will put the pull request on the TSC meeting agenda.

Helpful resources

• How to respectfully and usefully review code, part one and two
• How to write a positive code review

Waiting for Approvals

Before landing pull requests, sufficient time should be left for input from other Collaborators. In general, leave at least 48 hours to account for international time differences and work schedules. However, certain types of pull requests can be fast-tracked and may be landed after a shorter delay. For example:

• Focused changes that affect only documentation and/or the test suite:
  • code-and-learn tasks typically fall into this category.
  • good-first-issue pull requests may also be suitable.
• Changes that fix regressions:
  • Regressions that break the workflow (red CI or broken compilation).
  • Regressions that happen right before a release, or reported soon after.

When a pull request is deemed suitable to be fast-tracked, label it with fast-track and add a comment that collaborators may upvote. Please mention any Collaborators that previously approved the pull request. If someone disagrees with the fast-tracking request, remove the label and leave a comment indicating why the pull request should not be fast-tracked. The pull request can be landed once two or more Collaborators approve both the pull request and the fast-tracking request, and the necessary CI testing is done. A request to fast-track a PR made by a different Collaborator than the pull-request author counts as a fast-track approval.

Testing and CI

All bugfixes require a test case which demonstrates the defect. The test should fail before the change, and pass after the change.

All pull requests that modify executable code should also include a test case and must be subjected to continuous integration tests on the project CI server. The pull request should have a CI status indicator.

Do not land any Pull Requests without passing (green or yellow) CI runs. If you believe any failed (red or grey) CI sub-tasks are unrelated to the change in the Pull Request, use "Resume Build" in the left navigation of the relevant node-test-pull-request job. It will create a new node-test-pull-request run that preserves all the green results from the current job but re-runs everything else.

Useful CI Jobs

• node-test-pull-request is the standard CI run we do to check Pull Requests. It triggers node-test-commit, which runs the build-ci and test-ci targets on all supported platforms.

• node-test-pull-request-lite-pipeline only runs the linter job, as well as the tests on LinuxONE, which is very fast. This is useful for changes that only affect comments or documentation.

• citgm-smoker uses CitGM to allow you to run npm install && npm test on a large selection of common modules. This is useful to check whether a change will cause breakage in the ecosystem. To test Node.js ABI changes you can run citgm-abi-smoker.

• node-stress-single-test is designed to allow one to run a group of tests over and over on a specific platform to confirm that the test is reliable.

• node-test-commit-v8-linux is designed to allow validation of changes to the copy of V8 in the Node.js tree by running the standard V8 tests. It should be run whenever the level of V8 within Node.js is updated or new patches are floated on V8.

• node-test-commit-custom-suites can be used to customize what tests are run and with what parameters. For example, it can be used to execute tests which are not executed in a typical node-test-commit run (such as tests in the internet or pummel directories). It can also be used to make sure tests pass when provided with a flag not typically used in other CI test runs (such as --worker).

Internal vs. Public API

Due to the nature of the JavaScript language, it can often be difficult to establish a clear distinction between which parts of the Node.js implementation represent the public API Node.js users should assume to be stable and which are part of the internal implementation details of Node.js itself. A rule of thumb is to base the determination off what functionality is actually documented in the official Node.js API documentation. However, it has been repeatedly demonstrated that either the documentation does not completely cover implemented behavior or that Node.js users have come to rely heavily on undocumented aspects of the Node.js implementation.

The following general rules should be followed to determine which aspects of the Node.js API are internal:

• All functionality exposed via process.binding(...) is internal.
• All functionality implemented in lib/internal/**/*.js is internal unless it is re-exported by code in lib/*.js or documented as part of the Node.js Public API.
• Any object property or method whose key is a non-exported Symbol is an internal property.
• Any object property or method whose key begins with the underscore _ prefix is internal unless it is documented as part of the Node.js Public API.
• Any object, property, method, argument, behavior, or event not documented in the Node.js documentation is internal.
• Any native C/C++ APIs/ABIs exported by the Node.js *.h header files that are hidden behind the NODE_WANT_INTERNALS flag are internal.

Exceptions can be made if use or behavior of a given internal API can be demonstrated to be sufficiently relied upon by the Node.js ecosystem such that any changes would cause too much breakage. The threshold for what qualifies as too much breakage is to be decided on a case-by-case basis by the TSC.

If it is determined that a currently undocumented object, property, method, argument, or event should be documented, then a pull request adding the documentation is required in order for it to be considered part of the public API.

Making a determination about whether something should be documented can be difficult and will need to be handled on a case-by-case basis. For instance, if one documented API cannot be used successfully without the use of a second currently undocumented API, then the second API should be documented. If using an API in a manner currently undocumented achieves a particular useful result, a decision will need to be made whether or not that falls within the supported scope of that API; and if it does, it should be documented.

See Breaking Changes to Internal Elements on how to handle those types of changes.

Breaking Changes

Backwards-incompatible changes may land on the master branch at any time after sufficient review by Collaborators and approval of at least two TSC members.

Examples of breaking changes include:

• removal or redefinition of existing API arguments
• changing return values
• removing or modifying existing properties on an options argument
• adding or removing errors
• altering expected timing of an event
• changing the side effects of using a particular API

Purely additive changes (e.g. adding new events to EventEmitter implementations, adding new arguments to a method in a way that allows existing code to continue working without modification, or adding new properties to an options argument) are semver-minor changes.

Breaking Changes and Deprecations

With a few exceptions outlined below, when backward-incompatible changes to a Public API are necessary, the existing API must be deprecated first and the new API either introduced in parallel or added after the next major Node.js version following the deprecation as a replacement for the deprecated API. In other words, as a general rule, existing Public APIs must not change (in a backward-incompatible way) without a deprecation.

Exceptions to this rule may be made in the following cases:

• Adding or removing errors thrown or reported by a Public API;
• Changing error messages for errors without error code;
• Altering the timing and non-internal side effects of the Public API.

Such changes must be handled as semver-major changes but MAY be landed without a Deprecation cycle.

Note that errors thrown, along with behaviors and APIs implemented by dependencies of Node.js (e.g. those originating from V8) are generally not under the control of Node.js and therefore are not directly subject to this policy. However, care should still be taken when landing updates to dependencies when it is known or expected that breaking changes to error handling may have been made. Additional CI testing may be required.

From time-to-time, in particularly exceptional cases, the TSC may be asked to consider and approve additional exceptions to this rule.

For more information, see Deprecations.

Breaking Changes to Internal Elements

Breaking changes to internal elements are permitted in semver-patch or semver-minor commits but Collaborators should take significant care when making and reviewing such changes. Before landing such commits, an effort must be made to determine the potential impact of the change in the ecosystem by analyzing current use and by validating such changes through ecosystem testing using the Canary in the Goldmine tool. If a change cannot be made without ecosystem breakage, then TSC review is required before landing the change as anything less than semver-major.

If a determination is made that a particular internal API (for instance, an underscore _ prefixed property) is sufficiently relied upon by the ecosystem such that any changes may break user code, then serious consideration should be given to providing an alternative Public API for that functionality before any breaking changes are made.

When Breaking Changes Actually Break Things

Because breaking (semver-major) changes are permitted to land on the master branch at any time, at least some subset of the user ecosystem may be adversely affected in the short term when attempting to build and use Node.js directly from the master branch. This potential instability is why Node.js offers distinct Current and LTS release streams that offer explicit stability guarantees.

Specifically:

• Breaking changes should never land in Current or LTS except when:
  • Resolving critical security issues.
  • Fixing a critical bug (e.g. fixing a memory leak) requires a breaking change.
  • There is TSC consensus that the change is required.
• If a breaking commit does accidentally land in a Current or LTS branch, an attempt to fix the issue will be made before the next release; If no fix is provided then the commit will be reverted.

When any changes are landed on the master branch and it is determined that the changes do break existing code, a decision may be made to revert those changes either temporarily or permanently. However, the decision to revert or not can often be based on many complex factors that are not easily codified. It is also possible that the breaking commit can be labeled retroactively as a semver-major change that will not be backported to Current or LTS branches.

Reverting commits

Commits are reverted with git revert <HASH>, or git revert <FROM>..<TO> for multiple commits. Commit metadata and the reason for the revert should be appended. Commit message rules about line length and subsystem can be ignored. A Pull Request should be raised and approved like any other change.

Introducing New Modules

Semver-minor commits that introduce new core modules should be treated with extra care.

The name of the new core module should not conflict with any existing module in the ecosystem unless a written agreement with the owner of those modules is reached to transfer ownership.

If the new module name is free, a Collaborator should register a placeholder in the module registry as soon as possible, linking to the pull request that introduces the new core module.

Pull requests introducing new core modules:

• Must be left open for at least one week for review.
• Must be labeled using the tsc-review label.
• Must have signoff from at least two TSC members.

New core modules must be landed with a Stability Index of Experimental, and must remain Experimental until a semver-major release.

Additions to N-API

N-API provides an ABI stable API that we will have to support in future versions without the usual option to modify or remove existing APIs on SemVer boundaries. Therefore, additions need to be managed carefully.

This guide outlines the requirements and principles that we should follow when approving and landing new N-API APIs (any additions to node_api.h and node_api_types.h).

Deprecations

Deprecation is "the discouragement of use of some … feature … or practice, typically because it has been superseded or is no longer considered efficient or safe, without completely removing it or prohibiting its use. It can also imply that a feature, design, or practice will be removed or discontinued entirely in the future."

Node.js uses three Deprecation levels:

• Documentation-Only Deprecation: A deprecation notice is added to the API documentation but no functional changes are implemented in the code. By default, there will be no warnings emitted for such deprecations at runtime. Documentation-only deprecations may trigger a runtime warning when Node.js is started with the --pending-deprecation flag or the NODE_PENDING_DEPRECATION=1 environment variable is set.

• Runtime Deprecation: A warning is emitted at runtime the first time that a deprecated API is used. The --throw-deprecation flag can be used to escalate such warnings into runtime errors that will cause the Node.js process to exit. As with Documentation-Only Deprecation, the documentation for the API must be updated to clearly indicate the deprecated status.

• End-of-life: The API is no longer subject to the semantic versioning rules. Backward-incompatible changes including complete removal of such APIs may occur at any time.

Documentation-Only Deprecations may be handled as semver-minor or semver-major changes. Such deprecations have no impact on the successful operation of running code and therefore should not be viewed as breaking changes.

Runtime Deprecations and End-of-life APIs (internal or public) must be handled as semver-major changes unless there is TSC consensus to land the deprecation as a semver-minor.

All Documentation-Only and Runtime deprecations will be assigned a unique identifier that can be used to persistently refer to the deprecation in documentation, emitted process warnings, or errors thrown. Documentation for these identifiers will be included in the Node.js API documentation and will be immutable once assigned. Even if End-of-Life code is removed from Node.js, the documentation for the assigned deprecation identifier must remain in the Node.js API documentation.

A Deprecation cycle is a major release during which an API has been in one of the three Deprecation levels. Documentation-Only Deprecations may land in a minor release but must not be upgraded to a Runtime Deprecation until the next major release.

No API can be moved to End-of-life without first having gone through a Runtime Deprecation cycle. However, there is no requirement that deprecated code must progress ultimately to End-of-Life. Documentation-only and runtime deprecations may remain indefinitely.

Communicate pending deprecations and associated mitigations with the ecosystem as soon as possible (preferably before the pull request adding the deprecation lands on the master branch). Use the notable-change label on all pull requests that add a new deprecation or move an existing deprecation to a new deprecation level.

Involving the TSC

Collaborators may opt to elevate pull requests or issues to the TSC. This should be done where a pull request:

• is labeled semver-major, or
• has a significant impact on the codebase, or
• is inherently controversial, or
• has failed to reach consensus amongst the Collaborators who are actively participating in the discussion.

Assign the tsc-review label or @-mention the @nodejs/tsc GitHub team if you want to elevate an issue to the TSC. Do not use the GitHub UI on the right-hand side to assign to @nodejs/tsc or request a review from @nodejs/tsc.

The TSC should serve as the final arbiter where required.

Landing Pull Requests

1. Avoid landing PRs that are assigned to someone else. Authors who wish to land their own PRs will self-assign them, or delegate to someone else. If in doubt, ask the assignee whether it is okay to land.
2. Never use GitHub's green "Merge Pull Request" button. Reasons for not using the web interface button:
   • The "Create a merge commit" method will add an unnecessary merge commit.
   • The "Squash and merge" method will add metadata (the PR #) to the commit title. If more than one author has contributed to the PR, squashing will only keep the most recent author.
   • The "Rebase and merge" method has no way of adding metadata to the commit.
3. Make sure the CI is done and the result is green. If the CI is not green, check for flaky tests and infrastructure failures. Please check if those were already reported in the appropriate repository (node and build) or not and open new issues in case they are not. If no CI was run or the run is outdated because code was pushed after the last run, please first start a new CI and wait for the result. If no CI is required, please leave a comment in case none is already present.
4. Review the commit message to ensure that it adheres to the guidelines outlined in the contributing guide.
5. Add all necessary metadata to commit messages before landing. If you are unsure exactly how to format the commit messages, use the commit log as a reference. See this commit as an example.

For PRs from first-time contributors, be welcoming. Also, verify that their git settings are to their liking.

All commits should be self-contained, meaning every commit should pass all tests. This makes it much easier when bisecting to find a breaking change.

Using git-node

In most cases, using the git-node command of node-core-utils should be enough to help you land a Pull Request. If you discover a problem when using this tool, please file an issue to the issue tracker.

Quick example:

$ npm install -g node-core-utils
$ git node land $PRID

If it's the first time you have used node-core-utils, you will be prompted to type the password of your GitHub account and the two-factor authentication code in the console so the tool can create the GitHub access token for you. If you do not want to do that, follow the node-core-utils guide to set up your credentials manually.

Technical HOWTO

Clear any am/rebase that may already be underway:

$ git am --abort
$ git rebase --abort

Checkout proper target branch:

$ git checkout master

Update the tree (assumes your repo is set up as detailed in CONTRIBUTING.md):

$ git fetch upstream
$ git merge --ff-only upstream/master

Apply external patches:

$ curl -L https://github.com/nodejs/node/pull/xxx.patch | git am --whitespace=fix

If the merge fails even though recent CI runs were successful, then a 3-way merge may be required. In this case try:

$ git am --abort
$ curl -L https://github.com/nodejs/node/pull/xxx.patch | git am -3 --whitespace=fix

If the 3-way merge succeeds you can proceed, but make sure to check the changes against the original PR carefully and build/test on at least one platform before landing. If the 3-way merge fails, then it is most likely that a conflicting PR has landed since the CI run and you will have to ask the author to rebase.

Check and re-review the changes:

$ git diff upstream/master

Check the number of commits and commit messages:

$ git log upstream/master...master

Squash commits and add metadata:

$ git rebase -i upstream/master

This will open a screen like this (in the default shell editor):

pick 6928fc1 crypto: add feature A
pick 8120c4c add test for feature A
pick 51759dc crypto: feature B
pick 7d6f433 test for feature B

# Rebase f9456a2..7d6f433 onto f9456a2
#
# Commands:
#  p, pick = use commit
#  r, reword = use commit, but edit the commit message
#  e, edit = use commit, but stop for amending
#  s, squash = use commit, but meld into previous commit
#  f, fixup = like "squash", but discard this commit's log message
#  x, exec = run command (the rest of the line) using shell
#
# These lines can be re-ordered; they are executed from top to bottom.
#
# If you remove a line here THAT COMMIT WILL BE LOST.
#
# However, if you remove everything, the rebase will be aborted.
#
# Note that empty commits are commented out

Replace a couple of picks with fixup to squash them into a previous commit:

pick 6928fc1 crypto: add feature A
fixup 8120c4c add test for feature A
pick 51759dc crypto: feature B
fixup 7d6f433 test for feature B

Replace pick with reword to change the commit message:

reword 6928fc1 crypto: add feature A
fixup 8120c4c add test for feature A
reword 51759dc crypto: feature B
fixup 7d6f433 test for feature B

Save the file and close the editor. You'll be asked to enter a new commit message for that commit. This is a good moment to fix incorrect commit logs, ensure that they are properly formatted, and add Reviewed-By lines.

• The commit message text must conform to the commit message guidelines.

• Modify the original commit message to include additional metadata regarding the change process. (The git node metadata command can generate the metadata for you.)

  • Required: A PR-URL: line that references the full GitHub URL of the original pull request being merged so it's easy to trace a commit back to the conversation that led up to that change.
  • Optional: A Fixes: X line, where X either includes the full GitHub URL for an issue, and/or the hash and commit message if the commit fixes a bug in a previous commit. Multiple Fixes: lines may be added if appropriate.
  • Optional: One or more Refs: lines referencing a URL for any relevant background.
  • Required: A Reviewed-By: Name <email> line for yourself and any other Collaborators who have reviewed the change.
    • Useful for @mentions / contact list if something goes wrong in the PR.
    • Protects against the assumption that GitHub will be around forever.

Run tests (make -j4 test or vcbuild test). Even though there was a successful continuous integration run, other changes may have landed on master since then, so running the tests one last time locally is a good practice.

Validate that the commit message is properly formatted using core-validate-commit.

$ git rev-list upstream/master...HEAD | xargs core-validate-commit

Optional: When landing your own commits, force push the amended commit to the branch you used to open the pull request. If your branch is called bugfix, then the command would be git push --force-with-lease origin master:bugfix. Don't manually close the PR, GitHub will close it automatically later after you push it upstream, and will mark it with the purple merged status rather than the red closed status. If you close the PR before GitHub adjusts its status, it will show up as a 0 commit PR and the changed file history will be empty. Also if you push upstream before you push to your branch, GitHub will close the issue with red status so the order of operations is important.

Time to push it:

$ git push upstream master

Close the pull request with a "Landed in <commit hash>" comment. If your pull request shows the purple merged status then you should still add the "Landed in .." comment if you added multiple commits.

Troubleshooting

Sometimes, when running git push upstream master, you may get an error message like this:

To https://github.com/nodejs/node
 ! [rejected]              master -> master (fetch first)
error: failed to push some refs to 'https://github.com/nodejs/node'
hint: Updates were rejected because the remote contains work that you do
hint: not have locally. This is usually caused by another repository pushing
hint: to the same ref. You may want to first integrate the remote changes
hint: (e.g. 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

That means a commit has landed since your last rebase against upstream/master. To fix this, pull with rebase from upstream and run the tests again (to make sure no interactions between your changes and the new changes cause any problems), and push again:

git pull upstream master --rebase
make -j4 test
git push upstream master

I Made a Mistake

• Ping a TSC member.
• #node-dev on freenode
• With git, there's a way to override remote trees by force pushing (git push -f). This should generally be seen as forbidden (since you're rewriting history on a repository other people are working against) but is allowed for simpler slip-ups such as typos in commit messages. However, you are only allowed to force push to any Node.js branch within 10 minutes from your original push. If someone else pushes to the branch or the 10 minute period passes, consider the commit final.
  • Use --force-with-lease to minimize the chance of overwriting someone else's change.
  • Post to #node-dev (IRC) if you force push.

Long Term Support

What is LTS?

Long Term Support (often referred to as LTS) guarantees application developers a 30-month support cycle with specific versions of Node.js.

You can find more information in the full release plan.

How does LTS work?

Once a Current branch enters LTS, changes in that branch are limited to bug fixes, security updates, possible npm updates, documentation updates, and certain performance improvements that can be demonstrated to not break existing applications. Semver-minor changes are only permitted if required for bug fixes and then only on a case-by-case basis with LTS WG and possibly Technical Steering Committee (TSC) review. Semver-major changes are permitted only if required for security-related fixes.

Once a Current branch moves into Maintenance mode, only critical bugs, critical security fixes, and documentation updates will be permitted.

Landing semver-minor commits in LTS

The default policy is to not land semver-minor or higher commits in any LTS branch. However, the LTS WG or TSC can evaluate any individual semver-minor commit and decide whether a special exception ought to be made. It is expected that such exceptions would be evaluated, in part, on the scope and impact of the changes on the code, the risk to ecosystem stability incurred by accepting the change, and the expected benefit that landing the commit will have for the ecosystem.

Any Collaborator who feels a semver-minor commit should be landed in an LTS branch should attach the lts-agenda label to the pull request. The LTS WG will discuss the issue and, if necessary, will escalate the issue up to the TSC for further discussion.

How are LTS Branches Managed?

There are multiple LTS branches, e.g. v8.x and v6.x. Each of these is paired with a staging branch: v8.x-staging and v6.x-staging.

As commits land on the master branch, they are cherry-picked back to each staging branch as appropriate. If the commit applies only to the LTS branch, the PR must be opened against the staging branch. Commits are selectively pulled from the staging branch into the LTS branch only when a release is being prepared and may be pulled into the LTS branch in a different order than they were landed in staging.

Any Collaborator may land commits into a staging branch, but only the release team should land commits into the LTS branch while preparing a new LTS release.

How can I help?

When you send your pull request, please include information about whether your change is breaking. If you think your patch can be backported, please include that information in the PR thread or your PR description. For more information on backporting, please see the backporting guide.

Several LTS related issue and PR labels have been provided:

• lts-watch-v6.x - tells the LTS WG that the issue/PR needs to be considered for landing in the v6.x-staging branch.
• lts-watch-v4.x - tells the LTS WG that the issue/PR needs to be considered for landing in the v4.x-staging branch.
• land-on-v6.x - tells the release team that the commit should be landed in a future v6.x release
• land-on-v4.x - tells the release team that the commit should be landed in a future v4.x release

Any Collaborator can attach these labels to any PR/issue. As commits are landed into the staging branches, the lts-watch- label will be removed. Likewise, as commits are landed in a LTS release, the land-on- label will be removed.

Collaborators are encouraged to help the LTS WG by attaching the appropriate lts-watch- label to any PR that may impact an LTS release.

How is an LTS release cut?

When the LTS working group determines that a new LTS release is required, selected commits will be picked from the staging branch to be included in the release. This process of making a release will be a collaboration between the LTS working group and the Release team.

Who to CC in the issue tracker

Subsystem	Maintainers
benchmark/*	@nodejs/benchmarking, @mscdex
doc/*, *.md	@nodejs/documentation
lib/assert	@nodejs/assert
lib/async_hooks	@nodejs/async_hooks for bugs/reviews (+ @nodejs/diagnostics for API)
lib/buffer	@nodejs/buffer
lib/child_process	@nodejs/child_process
lib/cluster	@nodejs/cluster
lib/{crypto,tls,https}	@nodejs/crypto
lib/dgram	@nodejs/dgram
lib/domains	@nodejs/domains
lib/fs, src/{fs,file}	@nodejs/fs
lib/{_}http{*}	@nodejs/http
lib/inspector.js, src/inspector_*	@nodejs/v8-inspector
lib/internal/bootstrap/*	@nodejs/process
lib/internal/url, src/node_url	@nodejs/url
lib/net	@bnoordhuis, @indutny, @nodejs/streams
lib/repl	@nodejs/repl
lib/{_}stream{*}	@nodejs/streams
lib/timers	@nodejs/timers
lib/util	@nodejs/util
lib/zlib	@nodejs/zlib
src/async_wrap.*	@nodejs/async_hooks
src/node_api.*	@nodejs/n-api
src/node_crypto.*	@nodejs/crypto
test/*	@nodejs/testing
tools/node_modules/eslint, .eslintrc	@nodejs/linting
build	@nodejs/build
src/module_wrap.*, lib/internal/modules/*, lib/internal/vm/module.js	@nodejs/modules
GYP	@nodejs/gyp
performance	@nodejs/performance
platform specific	@nodejs/platform-{aix,arm,freebsd,macos,ppc,smartos,s390,windows}
python code	@nodejs/python
upgrading c-ares	@rvagg
upgrading http-parser	@nodejs/http, @nodejs/http2
upgrading libuv	@nodejs/libuv
upgrading npm	@fishrock123, @MylesBorins
upgrading V8	@nodejs/V8, @nodejs/post-mortem
Embedded use or delivery of Node.js	@nodejs/delivery-channels

When things need extra attention, are controversial, or semver-major: @nodejs/tsc

If you cannot find who to cc for a file, git shortlog -n -s <file> may help.