mongodb/docs/branching

Branching

This document describes branching task regarding file updates in 10gen/mongo repository that should be done on a new branch after a branch cut.

Table of contents

• 1. Create working branch
• 2. Update files
  • Copybara configuration
  • YAML configurations
    • Nightly YAML
    • Sys-perf YAML
  • Other files
• 3. Test changes
• 4. Merge changes

1. Create working branch

To save time during the branch cut these branching changes could be done beforehand, but not too early to avoid extra file conflicts, and then rebased on a new vX.Y branch.

Create a working branch from master or from a new vX.Y branch if it already exists:

git checkout master
git pull
git checkout -b vX.Y-branching-task

2. Update files

IMPORTANT! All of these changes should be a separate commit, but they should be pushed together in the same commit-queue task.

The reason they should be pushed as separate commits is in the case of needing to revert one aspect of this entire task.

Copybara configuration

copy.bara.sky and copy.bara.staging.sky

• Update "master" branch references with a new branch name

Evergreen YAML configurations

Nightly YAML

• etc/evergreen_nightly.yml will be used as YAML configuration for a new mongodb-mongo-vX.Y evergreen project

  • Copy over commit-queue aliases and patch aliases from etc/evergreen.yml

  • Update "include" section - comment out or uncomment file includes as instructions in the comments suggest.

    This will move some build variants from etc/evergreen.yml to continue running on a new branch project. More information about build variants after branching is here.

• burn_in_tags configuration

  • Remove build variant names from "burn_in_tag_include_build_variants" expansion that are not included in etc/evergreen_nightly.yml

• Remove all-feature-flags configuration from build variants

  • Build variant names:

    • enterprise-windows-all-feature-flags-required
    • enterprise-windows-all-feature-flags-non-essential
    • rhel8-debug-aubsan-lite-all-feature-flags-required

  • Actions:

    • Remove all-feature-flags from their names and display names
    • Remove --runAllFeatureFlagTests from test_flags expansion
    • Replace !.incompatible_all_feature_flags tag selectors with !.requires_all_feature_flags

• Promote build variants from "suggested" to "required"

  • Build variant names:

    • enterprise-amazon-linux2-arm64

  • Actions:

    • Replace "*" with "!" in their display names
    • Replace "suggested" variant tag with "required"

Sys-perf YAML

• etc/system_perf.yml will be used as YAML configuration for a new sys-perf-X.Y evergreen project

  • Ensure that DSI and Genny have been updated with new branches
  • Remove evergreen/system_perf/master/master_variants.yml from "include" section
  • Update evergreen/system_perf/master/variants.yml to evergreen/system_perf/X.Y/variants.yml in the "include" section
  • Update evergreen/system_perf/master/genny_tasks.yml to evergreen/system_perf/X.Y/genny_tasks.yml in the "include" section
  • Update the evergreen project variable compile_project in the new sys-perf-X.X evergreen project to point to the new mongodb-mongo-X branch

Other files

• buildscripts/generate_version_expansions.py

  • Update suffixes from "latest" to "vX.Y-latest", where vX.Y is a new branch name

3. Test changes

In case working branch was created from master branch, rebase it on a new vX.Y branch and fix file conflicts if any.

Schedule required patch on a new mongodb-mongo-vX.Y project:

evergreen patch -p mongodb-mongo-vX.Y -a required

If patch results reveal that some steps are missing or outdated in this file, make sure to update the branching documentation on a "master" branch accordingly.

4. Merge changes

All the commits should be pushed together in the same commit-queue task:

evergreen commit-queue merge -p mongodb-mongo-vX.Y