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Development Workflow

“How do I contribute code to this project?”

First off, take a moment to review our Best Practices before writing or submitting any code.

Git Workflow

No direct changes should be pushed to the build-artifact repository. The process of syncing these repositories is managed transparently in the background.

There are a few recommended Git workflows to consider, with the size of the team being a large influencing factor as to which workflow you might go with.

Feature Branch Workflow

The Feature Branch Workflow encourages all feature development work to take place on a dedicated branch, instead of committing locally to the standard master branch. The specifics are as follows:

  • A developer creates a new branch based on an up-to-date master branch to start work on a new feature.
  • When the work is completed, the "feature branch" is pushed to origin (or whatever name the developer gave the remote of their forked repository).
  • A pull request is opened against the master branch, giving other team members the chance to review the work completed prior to merging into master.
  • Once the work is accepted, it is merged into the master branch.

The above flow is best-suited for a small team. For a larger team, however, the Gitflow Workflow should be considered.

Gitflow Workflow

The Gitflow Workflow builds on the concept of the feature branch workflow. In addition to developers committing to feature branches instead of directly to master, they will additionally submit pull requests against a develop branch, that serves as an integration branch for new features. The specifics are as follows:

  • A developer creates a new branch based on an up-to-date develop branch to start work on a new feature.
  • When the work is completed, the "feature branch" is pushed to origin.
  • A pull request is opened against the develop branch, giving other team members the chance to review the work completed prior to merging into develop.
  • Once the desired set of features has been merged into the develop branch (or as the Atlassian docs mention, a predetermined release date has approached) a new release branch is created off of develop.
  • From then on, the release branch can be worked on by one team or the release master to add only what is necessary for the release, while the rest of the team is able to continue feature development against the develop branch.
  • The release branch is eventually merged into master, and develop rebased onto master upon merging.

This flow allows a larger team to work off an integrated branch (develop), all while maintaining a stable master branch that remains in a good state.

Gitflow Workflow (abridged version)

The Gitflow Workflow builds on the concept of the feature branch workflow. In addition to developers committing to feature branches instead of directly to master, they will additionally submit pull requests against a develop branch, that serves as an integration branch for new features. The specifics are as follows:

  • A developer creates a new branch based on an up-to-date develop branch to start work on a new feature.
  • When the work is completed, the "feature branch" is pushed to origin.
  • A pull request is opened against the develop branch, giving other team members the chance to review the work completed prior to merging into develop.
  • Once the desired set of features has been merged into the develop branch and the branch is known to be in a good state, it is merged into the master branch.

This flow still allow a team to work off an integrated branch (develop), all while maintaining a stable master branch, but removes the release branch portion of the flow.

Note: In all flows above, hotfixes are merged directly into a hotfix branch, which can then be merged to master.

Beginning work locally

  1. Pull a ticket in JIRA
  2. Create a new local feature branch named according to the following pattern: abc-123-short-desc Where "ABC" is the Jira prefix of your Jira project and "123" is the ticket number for which the work is being performed.
  3. Make your code changes.
  4. Commit your changes. Each commit should be logically atomic, and your commit messages should follow the pattern: "ABC-123 A grammatically correct sentence ending within punctuation."

Creating a Pull Request

The steps below assume use of a Gitflow Workflow.

For any work, pull requests must be created for individual tasks and submitted for review. Before submitting a pull request, be sure to sync the local branch with the upstream primary branch -

git checkout develop
git pull upstream develop
git push origin develop
git checkout -b XXX-<new-issue-branch> develop

If you created many small commits locally while working through a ticket, you should clean the history so that it can be easily reviewed. You can combine these commits using git rebase.

git rebase -i upstream/master

Pull requests should never contain merge commits from upstream changes.

Push your feature branch to your fork of the upstream repository, and submit a Pull Request from your-fork/feature-branch to canonical-repo/develop. You may optionally use Hub to submit your pull request from the command line.

hub pull-request

In order to enforce consistency on a project, a pull request template can also be configured using hub -

git config --global --add hub.pull-request-template-path ~/.pr-template

Resolving merge conflicts

Merge conflicts result when multiple developers submit PRs modifying the same code and Git cannot automatically resolve the conflict. For instance, if two developers add update hooks to the same module at the same time, these will necessarily conflict, because update hooks must be numbered in a defined sequence.

Developers are responsible for fixing merge conflicts on their own PRs. Follow this process to resolve a merge conflict:

  1. Fetch upstream history: git fetch upstream
  2. Check out the branch against which you opened your PR (e.g. master): git checkout master
  3. Make sure it matches upstream: git reset --hard upstream/master
  4. Check out your feature branch: git checkout feature/foo
  5. Merge master (this is where the magic happens): git merge master
  6. At this point, Git will complain about a merge conflict. Run git status to find the conflicting file(s).
  7. Edit the files to fix the conflict. The resources at the end of this section provide more information on this process.
  8. Use git add to add all of the files you fixed.
  9. Finally, run git commit to finish the merge, and git push origin feature/foo to update the PR.

Additional resources:

Integration (merging pull requests)

Two versions of the integration workflow are recommended -

  1. Integration manager
  2. Peer review

In either workflow, no one should ever commit their own code to the primary working branch.

Integration Manager

This model requires one (or more) lead developers to take the responsibility of merging all pull requests. This ensures consistency in quality control as well as identifying any potential issues with related, open pull requests.

A small group of one or more person(s) is selected to be integrators. All commits are reviewed by this group. If work is done by an integrator, their work should be reviewed by a fellow integrator (as if they were a developer).

Peer Review

This model removes the bottleneck of designated integrators, but still eliminates commits directly to the working branch. In short, every commit is reviewed by a developer other than the one submitting the original commit.

Continuous Integration

After a Pull Request has been submitted or merged, our continuous integration solution will automatically build a site artifact, install an ephemeral instance of Drupal, and execute tests against it. For more information on the build process, please see the Continuous Integration documentation.

Deployment on Cloud

Once work has been merged on GitHub and tested via the CI solution, a separate production-ready built artifact will be built and deployed to Acquia Cloud. This can be done either manually or automatically.

Please see deploy.md for more information.

Release Process

A designated Release Master will perform the release to production. This is typically the project’s Technical Architect. See the Release Process document for detailed information.