Chapter 33. OpenShift Pipeline
33.1. Overview
OpenShift Pipelines give you control over building, deploying, and promoting your applications on OpenShift. Using a combination of the Jenkins Pipeline Build Strategy, Jenkinsfiles, and the OpenShift Domain Specific Language (DSL) (provided by the OpenShift Jenkins Client Plug-in), you can create advanced build, test, deploy, and promote pipelines for any scenario.
33.2. OpenShift Jenkins Client Plug-in
The OpenShift Jenkins Client Plug-in must be installed on your Jenkins master so the OpenShift DSL will be available to use within the JenkinsFile for your application. This plug-in is installed and enabled by default when using the OpenShift Jenkins image.
33.2.1. OpenShift DSL
The OpenShift Jenkins Client Plug-in provides a fluent-styled DSL for communicating with the OpenShift API from within the Jenkins slaves. The OpenShift DSL is based on Groovy syntax and provides methods for controlling the lifecycle of your application such as create, build, deploy, and delete.
The full details of the API are embedded within the plug-in’s online documentation within a running Jenkins instance. To find it:
- Create a new Pipeline Item.
- Click Pipeline Syntax below the DSL text area.
- From the left navigation menu, click Global Variables Reference.
33.3. Jenkins Pipeline Strategy
In order to take advantage of the OpenShift Pipelines within your project, you will must use the Jenkins Pipeline Build Strategy. This strategy defaults to using a jenkinsfile at the root of your source repository, but also provides the following configuration options:
-
An inline
jenkinsfilefield within your BuildConfig. -
A
jenkinsfilePathfield within your BuildConfig that references the location of thejenkinsfileto use relative to the sourcecontextDir.
The optional jenkinsfilePath field specifies the name of the file to use, relative to the source contextDir. If contextDir is omitted, it defaults to the root of the repository. If jenkinsfilePath is omitted, it defaults to jenkinsfile.
For more detailed information about the Jenkins Pipeline Strategy, see Pipeline Strategy Options.
33.4. Jenkinsfile
The jenkinsfile utilizes the standard groovy language syntax to allow fine grained control over the configuration, build, and deployment of your application.
The jenkinsfile can be supplied in one of the following ways:
- A file located within your source code repository.
-
Embedded as part of your build configuration using the
jenkinsfilefield.
When using the first option, the jenkinsfile must be included in your applications source code repository at one of the following locations:
-
A file named
jenkinsfileat the root of your repository. -
A file named
jenkinsfileat the root of the sourcecontextDirof your repository. -
A file name specified via the
jenkinsfilePathfield of theJenkinsPiplineStrategysection of your BuildConfig, which is relative to the sourcecontextDirif supplied, otherwise it defaults to the root of the repository.
The jenkinsfile is executed on the Jenkins slave pod, which must have the OpenShift Client binaries available if you intend to use the OpenShift DSL.
33.5. Tutorial
For a full walkthrough of building and deploying an application with Jenkins Pipeline, see Jenkins Pipeline Tutorial.
33.6. Advanced Topics
33.6.1. Disabling Jenkins AutoProvisioning
When a Pipeline build configuration is created, OpenShift checks to see if there is currently a Jenkins master pod provisioned in the current project. If no Jenkins master is found, one is automatically created. If this behavior is not desirable, or if you would like to use a Jenkins server external to OpenShift, you can disable it.
33.6.2. Configuring Slave Pods
The Kubernetes Plug-in is also pre-installed in the official Jenkins image. This plug-in allows the Jenkins master to create slave pods on OpenShift and delegate running jobs to them to achieve scalability as well as providing pods with specific runtimes for specific jobs.
For more detailed information on configuring slave pods using the Kubernetes Plug-in, see Kubernetes Plug-in.
