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Jenkins Docker Image

This repository contains Dockerfiles for Jenkins Docker images intended for use with OpenShift v3

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

The images are pushed to DockerHub as openshift/jenkins-2-centos7, openshift/jenkins-slave-base-centos7, openshift/jenkins-slave-maven-centos7, openshift/jenkins-slave-nodejs-centos7, openshift/jenkins-agent-35-centos7, and openshift/jenkins-agent-nodejs-8-centos7.

The slave-maven and slave-nodejs for both centos7 and rhel7 are being deprecated as part of v3.10 of OpenShift. Additionally, development of these images will cease as of v3.10.

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

Versions

Jenkins versions currently provided are:

RHEL versions currently supported are:

  • RHEL7

CentOS versions currently supported are:

  • CentOS7

Installation

Choose either the CentOS7 or RHEL7 based image:

Notice: By omitting the VERSION parameter, the build/test action will be performed on all provided versions of Jenkins.

If you are curious about the precise level of Jenkins for either jenkins-2-centos7 or jenkins-2-rhel7, then you can execute:

$ docker run -it <image spec> /etc/alternatives/java -jar /usr/lib/jenkins/jenkins.war --version

For example:

$ docker run -it docker.io/openshift/jenkins-2-centos7:latest /etc/alternatives/java -jar /usr/lib/jenkins/jenkins.war --version

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 Jenkins 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)
OVERRIDE_PV_CONFIG_WITH_IMAGE_CONFIG When running this image with an OpenShift persistent volume for the Jenkins config directory, the transfer of configuration from the image to the persistent volume is only done the first startup of the image as the persistent volume is assigned by the persistent volume claim creation. If you create a custom image that extends this image and updates configuration in the custom image after the initial startup, by default it will not be copied over, unless you set this environment variable to some non-empty value.
OVERRIDE_PV_PLUGINS_WITH_IMAGE_PLUGINS When running this image with an OpenShift persistent volume for the Jenkins config directory, the transfer of plugins from the image to the persistent volume is only done the first startup of the image as the persistent volume is assigned by the persistent volume claim creation. If you create a custom image that extends this image and updates plugins in the custom image after the initial startup, by default they will not be copied over, unless you set this environment variable to some non-empty value.
OVERRIDE_RELEASE_MIGRATION_OVERWRITE When running this image with an OpenShift persistent volume for the Jenkins config directory, and this image is starting in an existing deployment created with an earlier version of this image, unless the environment variable is set to some non-empty value, the plugins from the image will replace any versions of those plugins currently residing in the Jenkins plugin directory.
SKIP_NO_PROXY_DEFAULT This environment variable applies to the agent/slave images produced by this repository. By default, the agent/slave images will create/update the 'no_proxy' environment variable with the hostnames for the Jenkins server endpoint and Jenkins JNLP endpoint, as communication flows to endpoints typically should NOT go through a HTTP Proxy. However, if your use case dictates those flows should not be exempt from the proxy, set this environment variable to any non-empty value.
ENABLE_FATAL_ERROR_LOG_FILE When running this image with an OpenShift persistent volume claim for the Jenkins config directory, this environment variable allows the fatal error log file to persist if a fatal error occurs. The fatal error file will be located at /var/lib/jenkins/logs.

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.

Inclusion of the oc binary

To assist in interacting with the OpenShift API server while using this image, the oc binary, the CLI command for OpenShift, has been installed in the master and slave images defined in this repository.

However, it needs to be noted that backward compatibility is not guaranteed between different versions of oc and the OpenShift API Server. As such, it is recommended that you align versions of this image present in the nodes of your cluster with your OpenShift API server. In other words, you should use the version specific tag instead of the latest tag.

Jenkins image version oc client version
jenkins-*-centos7:v3.7 3.7 oc binary
jenkins-*-centos7:v3.6 3.6 oc binary
jenkins-*-centos7:latest oc binary from docker.io/openshift/origin:latest image
jenkins-*-rhel7:v3.7 3.7 oc binary
jenkins-*-rhel7:v3.6 3.6 oc binary
jenkins-*-rhel7:latest 3.6 oc binary **

**Notice: the latest tag for the RHEL7 images will point to 3.6 indefinitely in order to support users on older clusters with older slave configurations that point to the "latest" tag. This way, they will have an older oc client which should be able to communicate with both 3.6 and newer versions of OpenShift API Servers. As the support policy is less stringent for the CentOS7 image, the latest tag there will make the more obvious correlation to the latest built version of OpenShift (which can include pre-GA versions).

**Notice: There is an additional consideration with the pod configurations for the Kubernetes Plugin; earlier versions of this image did not specify the "pull always" policy for the default agents/slaves configured. As a result, users may have older/different images on your nodes depending when the images were pulled. Starting with the 3.7 release, the default changed to "pull always" to avoid this problem in the future. But if you started using this image prior to 3.7, verification of your Kubernetes plugin configurations for the image pull policy used is warranted to guarantee consistency around what image is being used on each of your nodes.

Plugins

Base set of plugins

An initial set of Jenkins plugins are included in the OpenShift Jenkins images. The general methodology is that the CentOS7 image if first updated with any changes to the list of plugins. After some level of verification with that image, the RHEL7 image is updated.

Plugin installation for CentOS7

The top level list of plugins to install is located here. The format of the file is:

pluginId:pluginVersion

The file is processed by the following call in the CentOS7 Dockerfile:

/usr/local/bin/install-plugins.sh /opt/openshift/base-plugins.txt

Where both base-plugins.txt and install-plugins.sh are copied into the image prior to that invocation.

The running of install-plugins.sh will download the files listed in base-plugins.txt, and then open each plugin's manifest and download any needed dependencies listed, including upgrading any previously installed dependencies as needed.

To update the version of a plugin or add a new plugin, construct a PR for this repository that updates base-plugins.txt appropriately. Administrators for this repository will make sure necessary tests are run and merge the PR when things are ready.

When PRs for this repository are merged, they kick off associated builds in the push_jenkins_images job on OpenShift's public Jenkins CI/CD server. When those builds complete, new versions of the CentOS7 based versions of the images produced by this repository are pushed to Docker Hub. See the top of the README for the precise list.

Plugin installation for RHEL7

Only OpenShift developers working for Red Hat can update the list of plugins for the RHEL7 image. For those developers, visit this internal Jenkins server and log in (contact our CD team for permissions to this job). Click the Build with parameters link, update the PLUGIN_LIST field, and submit the build. The format of the data for the PLUGIN_LIST field is the same as base-plugins.txt.

The complete list of plugins (i.e. including dependencies) needs to be provided though. The most straight forward approach is to mine the output of the CentOS7 build which passed verification for the complete list. Just search for Installed plugins: and leverage copy/paste to compile what is needed.

Although this document will refrain on detailing the precise details, once the build on the internal Jenkins server is complete, the processes will be set in motion to build the jenkins-2-plugins RPM that is installed by the RHEL7 Dockerfile when the next version of the RHEL7 based OpenShift Jenkins image is built. When new versions of OpenShift are released, associated versions of the RHEL7 based versions of the images produced by this repository are pushed to the Docker registry provided to RHEL7 subscribers.

Some reference links for the OpenShift Jenkins developers and where things cross over with the CD/CL/Atomic/RHEL teams:

Adding plugins or updating existing plugins

A combination of the contents of this repository and the capabilities of OpenShift allow for a variety of ways to modify the list of plugins either for the images directly produced from this repository, or by creating images which build from the images directly produced from this repository.

The specifics for each approach are detailed below.

Installing using layering

In order to install additional Jenkins plugins, the OpenShift Jenkins image provides a way similar to how the initial set of plugins are added to this image that will allow one to add or update 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 a derived image in this fashion, create the following Dockerfile:

FROM openshift/jenkins-2-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 OpenShift 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-2-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 focused on integration with OpenShift

A subset of the plugins included by the images of this repository play a direct part in integrating between Jenkins and OpenShift.

  • OpenShift Pipeline Plugin Visit the upstream repository, which demonstrates example usage of the plugin's capabilities with the OpenShift Sample Job included in this image. For more details visit the Jenkins plugin website. Future development of this plugin is being deprioritized in favor of the OpenShift Client Plugin detailed below. But this plugin is still supported for existing users who have yet to finish migrating to OpenShift Client Plugin. It also serves as an option if the use of the oc binary from your Jenkins jobs is not viable for some reason (we are actually curious if such use cases in fact exist), as it interacts with OpenShift via HTTP REST. Remember though only a subset of the functionality provided by oc is available from this plugin.

  • 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 plugin, with its fluent styled syntax and use of the oc binary (exposing all the capabilities of that command), is the preferred choice for interacting with OpenShift via either Jenkins Pipeline or Freestyle jobs.

  • 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. It also facilitates auto-configuration of the slave pod templates for the Kubernetes Plugin. See the OpenShift documentation for more details.

  • OpenShift Login Plugin Visit the upstream repository as well as the Jenkins plugin wiki. This plugin integrates the authentication and authorization of your Jenkins instance with you OpenShift cluster, providing a single sign-on look and feel. You'll sign into the Jenkins server using the same credentials that you use to sign into the OpenShift Web Console or interact with OpenShift via the oc CLI. See the OpenShift documentation for more details.

For the above OpenShift Jenkins plugins, each of their READMEs have specifics unique to each of them on how to use and if so desired contribute to their development. That said, there is a good deal of commonality and shared infrastructure related to developing, creating new versions, and ultimately updating the images of this repository with those new versions. If you would like to understand the specifics of that process, please visit our plugin contribution guide.

  • Kubernetes Plugin Though not originated out of the OpenShift organization, this plugin is invaluable in that it 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 this plugin, visit the plugin web site.

Usage

For this, we will assume that you are using the openshift/jenkins-2-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-2-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 an OpenShift 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.

Users can choose between testing Jenkins based on a RHEL or CentOS image.

  • RHEL based image

    To test a RHEL7 based Jenkins image, you need to run the test on a properly subscribed RHEL machine.

    $ cd jenkins
$ make test TARGET=rhel7 VERSION=2

  • 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 2, you can omit this parameter.

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