Jenkins Build Per Git Flow Branch

This script will allow you to keep your Jenkins jobs in sync with your Git repository (following Git Flow branching model).

Genesis

This is a variation of a solution we found. Hence, the credit for the idea and initial implementation goes to Entagen and theirs Jenkins Build Per Branch. They explained it nicely, so it's advisable to take a look to their page. As stated, Entagen's version would suit better for a GitHub flow convention. Our need is to have three different templates for each of the Git Flow branches: features, releases, hotfixes and to sync them all in one 'scanning session' (single Jenkins sync job execution). I found it impossible using the original solution. So, we reused the concept of Entagen's script, but replaced the synchronization logic with what suited us better.

Installation

Requirements are the same for both script versions:

• Jenkins Git Plugin
• Jenkins Gradle plugin
• The git command line app also must be installed (this is already a requirement of the Jenkins Git Plugin), and it must be configured with credentials (likely an SSH key) that has authorization rights to the git repository
• The best idea is to clone / fork this repository for your own usage (to make sure that the script remain intact). However, you can still use ours if you like.

###Naming convention To make this script work properly, job names must follow few rules:

Template jobs should follow <templateJobPrefix>-<jobName>-<branchName> name, where:

• templateJobPrefix - a prefix which distinguish particular type of template (one template type can be reused among several projects (explained further)
• jobName - name of your Jenkins job purpose, ex. build etc.
• branchName - one of the 3 Git Flow branch types: feature, release, hotfix

Regular jobs should follow similar pattern <jobPrefix>-<jobName>-<branchName>, where:

• jobPrefix - is a prefix which distinguish particular project
• for jobName and branchName apply the same rule as for templates

Git Flow branches should start with feature-, hotfix-, release- prefixes. It is because, Jenkins is having hard time with slashes (i.e. feature/, hotfix/, release/). There are some workarounds (substituting '/' with and underscore for a jenkins job name - take a look into the code of Entagen version), but we were fine with this trade off.

Usage

Usage is also very similiar to the original, but let me retrace the steps:

1. Create Jenkins synchronization job

The whole idea is to have a single Jenkins job which executes periodically, checks Git repository and creates / removes Jenkins jobs for each of the Git Flow dynamic branch (other than master and development).

Note: If no template for particular branch / job is available, branch will be ignored (job won't be created nor deleted).

• Create new "Freestyle project" kind of Jenkins job.
• Name it accordingly, ex. ProjectName-SyncJobs.
• For Git URL provide this script location (or your forked / cloned one): [email protected]:neoteric-eu/jenkins-build-per-gitflow-branch.git
• Set appropriate branch to build (ours is origin/master)
• Make sure it's triggered periodically (ex. every 5 minutes: H/5 * * * *)
• Add a build step "Invoke Gradle script" and set it's Tasks field to syncWithRepo
• Provide script parameters (explained below) in Switches box

Important note from Entagen site: This job is potentially destructive as it will delete old feature branch jobs for feature branches that no longer exist. It's strongly recommended that you back up your jenkins jobs directory before running, just in case. Another good alternative would be to put your jobs directory under git version control. Ignore workspace and builds directories and just about everything can be added. Commit periodocally and if something bad happens, revert back to the last known good version.

2. Add script parameters (provided in Switches box)

• -DjenkinsUrl URL of the Jenkins.You should be able to append api/json to the URL to get JSON feed.
• -DjenkinsUser Jenkins HTTP basic authorization user name. (optional)
• -DjenkinsPasswrd Jenkins HTTP basic authorization password. (optional)
• -DgitUrl URL of the Git repository to make the synchronization against.
• -DdryRun Pass this flag with any value and it won't make any changes to Jenkins (preview mode). It is recommended to use dry run until everything is set up correctly. (optional)
• -DtemplateJobPrefix Prefix name of template jobs to use
• -DjobPrefix Prefix name of project jobs to create
• -DcreateJobInView If you want the script to create the job in a view provide the view name here. It also supports nested views, just separate them with a slash '/', ex. view/nestedview
• -DnoDelete pass this flag with true value to avoid removing obsolete jobs (with no corresponding git branch) (optional)

Sample parameters configuration:

-DjenkinsUrl=http://myjenkinshost.com:8080/
-DjenkinsUser=username
-DjenkinsPassword=password
[email protected]/project.git
-DtemplateJobPrefix=SimpleJarTemplate
-DjobPrefix=ProjectOne
-DcreateJobInView=ProjectOne

3. Templates

The idea of this script is to be able to handle separate template version per Git Flow branch type. What's more you can reuse a template set among your projects. For example, we are currently basing only on two sets of templates. One for simple jar modules and the second one for the final build of our micro services (built to Debian packages). In each set we have a template for each branch (feature, release, hotfix). Because of releasing and versioning capabilities we want to handle each branch type differently.

Notes on configuring your template:

• If you want to start your job immediately after it's created, mark the template as parametrized build and add a Boolean parameter named startOnCreate and set it's default value to true (tick in the checkbox)
• Git repository URL is going to be replaced by the script (with the project Git URL set in sync job parameters)
• Branch to build is going to be determined and set by the script
• If you use Sonar and want to have Sonar builds separated for each branch type, just add Sonar capability to your template and the Sonar branch option will be determined and set by the script