Git Flow

Git Flow
Git Flow
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Git Flow Workflow

This Git Flow mashup is derived from Vincent Driessen’s A Successful Git Branching Model and Atlassian’s Gitflow Workflow.

Credit is due to them. I’ve simply mashed up the two sources, edited some wording, and merged the two git command styles into one unified flow.

The pattern illustrated here uses git without the git flow module add-on; so just pure git commands.

How Git Flow Works

The Git Flow workflow uses a central repository as the communication hub for all developers. Developers work locally and push branches to the central repo.

Historical Branches

Instead of a single master branch, this workflow uses two branches to record the history of the project. The master branch stores the official release history, and the develop branch serves as an integration branch for features. It’s also convenient to tag all commits in the master branch with a version number.

The rest of this workflow revolves around the distinction between these two branches.

Feature Branches

Each new feature should reside in its own branch, which can be pushed to the central repository for backup/collaboration. But, instead of branching off of master, feature branches use develop as their parent branch. When a feature is complete, it gets merged back into develop. Features should never interact directly with master.

Best Practices:

  • May branch off: develop
  • Must merge back into: develop
  • Branch naming convention: anything except master, develop, release-*, or hotfix-*

Release Branches

Once develop has acquired enough features for a release (or a predetermined release date is approaching), you fork a release branch off of develop.

Creating this branch starts the next release cycle, so no new features can be added after this point-only bug fixes, documentation generation, and other release-oriented tasks should go in this branch.

Once it’s ready to ship, the release gets merged into master and tagged with a version number. In addition, it should be merged back into develop, which may have progressed since the release was initiated.

Using a dedicated branch to prepare releases makes it possible for one team to polish the current release while another team continues working on features for the next release. It also creates well-defined phases of development (e.g., it’s easy to say, “this week we’re preparing for version 4.0” and to actually see it in the structure of the repository).

Best Practices:

  • May branch off: develop
  • Must merge back into: develop and master
  • Tag: increment major or minor number
  • Branch naming convention: release-* or release/*

Maintenance Branches

Maintenance or “hotfix” branches are used to quickly patch production releases. This is the only branch that should fork directly off of master. As soon as the fix is complete, it should be merged into both master and develop (or the current release branch), and master should be tagged with an updated version number.

Having a dedicated line of development for bug fixes lets your team address issues without interrupting the rest of the workflow or waiting for the next release cycle. You can think of maintenance branches as ad hoc release branches that work directly with master.

Best Practices:

  • May branch off: master
  • Must merge back into: master and develop
  • Tag: increment patch number
  • Branch naming convention: hotfix-* or hotfix/*

Git Flow Example

The example below demonstrates how this workflow can be used to manage a single release cycle. We’ll assume you have already created a central repository.

Create A Develop Branch

The first step is to complement the default master with a develop branch. A simple way to do this is for one developer to create an empty develop branch locally and push it to the server:

git branch develop
git push -u origin develop

This branch will contain the complete history of the project, whereas master will contain an abridged version. Other developers should now clone the central repository and create a tracking branch for develop:

git clone ssh://user@host/path/to/repo.git
git checkout -b develop origin/develop

Everybody now has a local copy of the historical branches set up.

Mary And John Begin New Features

Our example starts with John and Mary working on separate features. They both need to create separate branches for their respective features. Instead of basing it on master, they should both base their feature branches on develop:

git checkout -b some-feature develop

# Optionally, push branch to origin:
git push -u origin some-feature

Both of them add commits to the feature branch in the usual fashion: edit, stage, commit:

git status
git add some-file
git commit

Mary Finishes Her Feature

After adding a few commits, Mary decides her feature is ready. If her team is using pull requests, this would be an appropriate time to open one asking to merge her feature into develop. Otherwise, she can merge it into her local develop and push it to the central repository, like so:

git pull origin develop
git checkout develop
git merge --no-ff some-feature
git push origin develop

git branch -d some-feature

# If you pushed branch to origin:
git push origin --delete some-feature

The first command makes sure the develop branch is up to date before trying to merge in the feature. Note that features should never be merged directly into master.

Mary Begins To Prepare A Release

While John is still working on his feature, Mary starts to prepare the first official release of the project. She uses a new branch to encapsulate the release preparations. This step is also where the release’s version number is established, and she uses the SemVer initial release recommendation of v0.1.0:

git checkout -b release-0.1.0 develop

# Optional: Bump version number, commit
# Prepare release, commit

This branch is a place to clean up the release, test everything, update the documentation, and do any other kind of preparation for the upcoming release. It’s like a feature branch dedicated to polishing the release.

As soon as Mary creates this branch and pushes it to the central repository, the release is feature-frozen. Any functionality that isn’t already in develop is postponed until the next release cycle.

Mary Finishes The Release

Once the release is ready to ship, Mary merges it into master and develop, then deletes the release branch. It’s important to merge back into develop because critical updates may have been added to the release branch and they need to be accessible to new features. Again, if Mary’s organization stresses code review, this would be an ideal place for a pull request.

git checkout master
git merge --no-ff release-0.1.0
git push

git checkout develop
git merge --no-ff release-0.1.0
git push

git branch -d release-0.1.0

# If you pushed branch to origin:
git push origin --delete release-0.1.0

Release branches act as a buffer between feature development (develop) and public releases (master). Whenever you merge something into master, you should tag the commit for easy reference:

git tag -a v0.1.0 master
git push --tags

Pro Tip: Git comes with several hooks, which are scripts that execute whenever a particular event occurs within a repository. It’s possible to configure a hook to automatically build a public release whenever you push the master branch to the central repository or push a tag.

End-user Discovers A Bug

After shipping the release, Mary goes back to developing features for the next release with John. That is, until an end-user opens a ticket complaining about a bug in the current release. To address the bug, Mary (or John) creates a maintenance branch off of master, fixes the issue with as many commits as necessary, then merges it directly back into master.

git checkout -b hotfix-0.1.1 master

# Optional: Bump version number, commit
# Fix the bug, commit

git checkout master
git merge --no-ff hotfix-0.1.1
git push

Like release branches, maintenance branches contain important updates that need to be included in develop, so Mary needs to perform that merge as well. Then, she’s free to delete the branch:

git checkout develop
git merge --no-ff hotfix-0.1.1
git push

git branch -d hotfix-0.1.1

Just like in the release branch, Mary has merged into master, so she needs to tag the commit on the master branch. By incrementing the patch number, she indicates this is a non-breaking maintenance release:

git tag -a v0.1.1 master
git push --tags

Now go forth and enjoy the “flow” in your own Git repos!