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Branches and Pull Requests

In the previous section a Jenkinsfile which could be checked into source control was implemented. This section covers the concept of Multibranch Pipelines which build on the Jenkinsfile foundation to provide more dynamic and automatic functionality in Jenkins.

Creating a Multibranch Pipeline

The Multibranch Pipeline project type enables you to implement different Jenkinsfiles for different branches of the same project. In a Multibranch Pipeline project, Jenkins automatically discovers, manages and executes Pipelines for branches which contain a Jenkinsfile in source control.

This eliminates the need for manual Pipeline creation and management.

To create a Multibranch Pipeline:

  • Click New Item on Jenkins home page.

Click *New Item* on the Jenkins home page
  • Enter a name for your Pipeline, select Multibranch Pipeline and click OK.

Jenkins uses the name of the Pipeline to create directories on disk. Pipeline names which include spaces may uncover bugs in scripts which do not expect paths to contain spaces.

Enter a name, select *Multibranch Pipeline*, and click *OK*
  • Add a Branch Source (for example, Git) and enter the location of the repository.

Add a Branch Source
Add the URL to the project repository
  • Save the Multibranch Pipeline project.

Upon Save, Jenkins automatically scans the designated repository and creates appropriate items for each branch in the repository which contains a Jenkinsfile.

By default, Jenkins will not automatically re-index the repository for branch additions or deletions (unless using an Organization Folder), so it is often useful to configure a Multibranch Pipeline to periodically re-index in the configuration:

Setting up branch re-indexing

Additional Environment Variables

Multibranch Pipelines expose additional information about the branch being built through the env global variable, such as:

BRANCH_NAME

Name of the branch for which this Pipeline is executing, for example master.

CHANGE_ID

An identifier corresponding to some kind of change request, such as a pull request number

Additional environment variables are listed in the Global Variable Reference.

Supporting Pull Requests

With the "GitHub" or "Bitbucket" Branch Sources, Multibranch Pipelines can be used for validating pull/change requests. This functionality is provided, respectively, by the GitHub Branch Source and Bitbucket Branch Source plugins. Please consult their documentation for further information on how to use those plugins.

Using Organization Folders

Organization Folders enable Jenkins to monitor an entire GitHub Organization, or Bitbucket Team/Project and automatically create new Multibranch Pipelines for repositories which contain branches and pull requests containing a Jenkinsfile.

Currently, this functionality exists only for GitHub and Bitbucket, with functionality provided by the GitHub Organization Folder and Bitbucket Branch Source plugins.