Docs header transparent bg


Bundler uses Semantic Versioning.

Note: In the documentation listed below, the *current* minor version number is 2.1 and the *next* minor version number is 2.2

Regardless of the version, all releases must update the and lib/bundler/version.rb files. The changelog for the first stable minor release (2.2.0) is a sum of all the preceding pre-release versions (2.2.pre.1, 2.2.pre.2, etc) for that minor version. The changelog for the first stable minor release is left blank unless there are fixes included since the last pre/rc release.


In general, master will accept PRs for:

  • feature merges for the next minor version (2.2)
  • regression fix merges for a patch release on the current minor version (2.1)
  • feature-flagged development for the next major version (2.0)

Breaking releases

Bundler cares a lot about preserving compatibility. As a result, changes that break backwards compatibility should (whenever this is possible) include a feature release that is backwards compatible, and issue warnings for all options and behaviors that will change.

We try very hard to only release breaking changes when incrementing the major version of Bundler.

Patch && minor releases

While pushing a gem version to is as simple as rake release, releasing a new version of Bundler includes a lot of communication: team consensus, git branching, documentation site updates, and a blog post.

Patch and minor releases are made by cherry-picking pill requests from master.


Bundler releases are synchronized with rubygems releases at the moment. That means that releases for both share the same stable branch, and they should generally happen together.

Minor releases of the next version start with a new release branch from the current state of master: 3.2, and are immediately followed by a prerelease (might be a .pre.1 version or a .rc.1 version depending on the readiness of the stable branch) or even directly by the final stable release.

The current conventional naming for stable branches is x+1.y, where x.y is the version of bundler that will be released. This is because rubygems-x+1.y will be released at the same time.

For example, rubygems-3.2.0 and bundler-2.2.0 will be both released from the 3.2 stable branch.

Once a stable branch has been cut from master, changes for that minor release series (bundler 2.2) will only be made intentionally, via patch releases. That is to say, changes to master by default won’t make their way into any 2.2 version, and development on master will be targeting the next minor or major release.

There is a rake prepare_stable_branch[<target_rubugems_version>] rake task that helps with creating a release. It takes a single argument, the exact rubygems release being made (e.g. 3.2.3 when releasing bundler 2.2.3). This task checks out the appropriate stable branch (3.2), grabs all merged but unreleased PRs from both bundler & rubygems from GitHub that are compatible with the target release level, and then cherry-picks those changes (and only those changes) to a new branch based off the stable branch. Then bumps the version in all version files, synchronizes both changelogs to include all backported changes and commits that change on top of the cherry-picks.

Note that this task requires all user facing pull requests to be tagged with specific labels. See Merging a PR for details.

Also note that when this task cherry-picks, it cherry-picks the merge commits using the following command:

bash $ git cherry-pick -m 1 MERGE_COMMIT_SHAS

For example, for PR #5029, we cherry picked commit dd6aef9, not 4fe9291 using:

bash $ git cherry-pick -m 1 dd6aef9

After running the task, you’ll have a release branch ready to be merged into the stable branch. You’ll want to open a PR from this branch into the stable branch and provided CI is green, you can go ahead, merge the PR and run bin/rake release from bundler/ directory in the updated stable branch.

Here’s the checklist for releasing new minor versions:

  • [ ] Check with the core team to ensure that there is consensus around shipping a feature release. As a general rule, this should always be okay, since features should never break backwards compatibility
  • [ ] Run rake prepare_stable_branch[<target_rubygems_pre_version>] and create a PR to the stable branch with the generated changes.
  • [ ] Get the PR reviewed, make sure CI is green, and merge it.
  • [ ] Pull the updated stable branch, wait for CI to complete on it and get excited.
  • [ ] Run bin/rake release from the bundler/ directory updated stable branch, tweet, blog, let people know about the prerelease!
  • [ ] Wait a minimum of 7 days
  • [ ] If significant problems are found, increment the prerelease (i.e. 2.2.pre.2) and repeat, but treating .pre.2 as a patch release. In general, once a stable branch has been cut from master, it should not have master merged back into it.

Wait! You’re not done yet! After your prelease looks good:

  • [ ] Run rake prepare_stable_branch[<target_rubygems_version>] and create a PR to the stable branch.
  • [ ] Get the PR reviewed, make sure CI is green, and merge it.
  • [ ] In the rubygems/bundler-site repo, copy the previous version’s docs to create a new version (e.g. cp -r v2.1 v2.2)
  • [ ] Update the new docs as needed, paying special attention to the “What’s new” page for this version
  • [ ] Write a blog post announcing the new version, highlighting new features and notable bugfixes
  • [ ] Pull the updated stable branch, wait for CI to complete on it and get excited.
  • [ ] Run bin/rake release in the bundler/ directory of the updated stable branch, tweet, link to the blog post, etc.

At this point, you’re a release manager! Pour yourself several tasty drinks and think about taking a vacation in the tropics.

Beware, the first couple of days after the first non-prerelease version in a minor version series can often yield a lot of bug reports. This is normal, and doesn’t mean you’ve done anything wrong as the release manager.

Beta testing

Early releases require heavy testing, especially across various system setups. We :heart: testers, and are big fans of anyone who can run gem install bundler --pre and try out upcoming releases in their development and staging environments.

There may not always be prereleases or beta versions of Bundler. The Bundler team will tweet from the @bundlerio account when a prerelease or beta version becomes available. You are also always welcome to try checking out master and building a gem yourself if you want to try out the latest changes.

Edit this document on GitHub if you caught an error or noticed something was missing.