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Jenkins Docker Image

This repository contains Dockerfiles for a Jenkins Docker image intended for use with Digital Garage

For an example of how to use it, see this sample.

The image is pushed to DockerHub as openshift/jenkins-1-centos7.

For more information about using these images with Digital Garage, please see the official Digital Garage Documentation.

Versions

Jenkins versions currently provided are:

CentOS versions currently supported are:

  • CentOS7

Installation

  • CentOS7 based image

    This image is available on DockerHub. To download it run:

    $ docker pull openshift/jenkins-1-centos7

    To build a Jenkins image from scratch run:

    $ git clone https://github.com/thedigitalgarage/jenkins.git
$ cd jenkins
$ make build VERSION=1

Notice: By omitting the VERSION parameter, the build/test action will be performed on all provided versions of Jenkins. Since we are currently providing only version 1, you can omit this parameter.

Environment variables

The image recognizes the following environment variables that you can set during initialization by passing -e VAR=VALUE to the Docker run command.

Variable name Description
JENKINS_PASSWORD Password for the 'admin' account when using default Jenkin authentication.
OPENSHIFT_ENABLE_OAUTH Determines whether the OpenShift Login plugin manages authentication when logging into Jenkins.
OPENSHIFT_PERMISSIONS_POLL_INTERVAL Specifies in milliseconds how often the OpenShift Login plugin polls OpenShift for the permissions associated with each user defined in Jenkins.
INSTALL_PLUGINS Comma-separated list of additional plugins to install on startup. The format of each plugin spec is plugin-id:version (as in plugins.txt)

You can also set the following mount points by passing the -v /host:/container flag to Docker.

Volume mount point Description
/var/lib/jenkins Jenkins config directory

Notice: When mounting a directory from the host into the container, ensure that the mounted directory has the appropriate permissions and that the owner and group of the directory matches the user UID or name which is running inside the container.

Plugins

Installing using layering

The Digital Garage Jenkins image provides a way to install additional Jenkins plugins by layering on top of this image. The derived image will provide the same functionality as described in this documentation. In addition it will also include all plugins you list in the plugins.txt file.

To create derived image, you have to write the following Dockerfile:

FROM openshift/jenkins-1-centos7
COPY plugins.txt /opt/openshift/configuration/plugins.txt
RUN /usr/local/bin/install-plugins.sh /opt/openshift/configuration/plugins.txt

The format of plugins.txt file is:

pluginId:pluginVersion

For example, to install the github Jenkins plugin, you specify following to plugins.txt:

github:1.11.3

After this, just run docker build -t my_jenkins_image -f Dockerfile.

Installing using S2I build

The s2i tool allows you to do additional modifications of this Jenkins image. For example, you can use S2I to copy custom Jenkins Jobs definitions, additional plugins or replace the default config.xml file with your own configuration.

To do that, you can either use the standalone s2i tool, that will produce the customized Docker image or you can use Digital Garage Source build strategy.

In order to include your modifications in Jenkins image, you need to have a Git repository with following directory structure:

  • ./plugins folder that contains binary Jenkins plugins you want to copy into Jenkins
  • ./plugins.txt file that list the plugins you want to install (see the section above)
  • ./configuration/jobs folder that contains the Jenkins job definitions
  • ./configuration/config.xml file that contains your custom Jenkins configuration

Note that the ./configuration folder will be copied into /var/lib/jenkins folder, so you can also include additional files (like credentials.xml, etc.).

To build your customized Jenkins image, you can then execute following command:

$ s2i build https://github.com/your/repository openshift/jenkins-1-centos7 your_image_name

NOTE: if instead of adding a plugin you want to replace an existing plugin via dropping the binary plugin in the ./plugins directory, make sure the filename ends in .jpi.

Installing on Startup

The INSTALL_PLUGINS environment variable may be used to install a set of plugins on startup. When using a persistent volume for /var/lib/jenkins, plugin installation will only happen on the initial run of the image.

In the following example, the Groovy and Pull Request Builder plugins are installed

INSTALL_PLUGINS=groovy:1.30,ghprb:1.35.0

Plugins of note

  • OpenShift Pipeline Plugin Visit the upstream repository, as well an example use of the plugin's capabilities with the OpenShift Sample Job included in this image. For more details visit the Jenkins plugin website.

  • OpenShift Client Plugin Visit the upstream repository as well as the Jenkins plugin wiki. With the lessons learned from OpenShift Pipeline Plugin, as well as adjustments to the rapid evolutions of both Jenkins and OpenShift, this experimental plugin, currently included in the Centos images for this repository, is viewed as the long term replacement for OpenShift Pipeline Plugin.

  • OpenShift Sync Plugin Visit the upstream repository as well as the Jenkins plugin wiki. This plugin facilitates the integration between the OpenShift Jenkinsfile Build Strategy and Jenkins Pipelines. See the OpenShift documentation for more details.

  • Kubernetes Plugin This plugin allows slaves to be dynamically provisioned on multiple Docker hosts using Kubernetes. To learn how to use this plugin, see the example available in the OpenShift Origin repository. For more details about plugin, visit the plugin web site.

Usage

For this, we will assume that you are using the openshift/jenkins-1-centos7 image. If you want to set only the mandatory environment variables and store the database in the /tmp/jenkins directory on the host filesystem, execute the following command:

$ docker run -d -e JENKINS_PASSWORD=<password> -v /tmp/jenkins:/var/lib/jenkins openshift/jenkins-1-centos7

Jenkins admin user

Authenticating into a Jenkins server running within the OpenShift Jenkins image is controlled by the OpenShift Login plugin, taking into account:

  • Whether or not the container is running in Digital Garage Pod
  • How the environment variables recognized by the image are set

See the OpenShift Login plugin documentation for details on how it manages authentication.

However, when the default authentication mechanism for Jenkins is used, if you are using the OpenShift Jenkins image, you log in with the user name admin, supplying the password specified by the JENKINS_PASSWORD environment variable set on the container. If you do not override JENKINS_PASSWORD, the default password for admin is password.

Test

This repository also provides a test framework which checks basic functionality of the Jenkins image.

  • CentOS based image

    $ cd jenkins
$ make test VERSION=2

Notice: By omitting the VERSION parameter, the build/test action will be performed on all provided versions of Jenkins. Since we are currently providing only version 1, you can omit this parameter.