OpenShift CI/CD Concepts: Difference between revisions
| Line 18: | Line 18: | ||
==Jenkins Images and Templates== | ==Jenkins Images and Templates== | ||
OpenShift provides a certified Jenkins container image, developed under https://github.com/openshift/jenkins repository. OpenShift also comes with two standard templates that use this image to create Jenkins infrastructure objects. The "jenkins-ephemeral" and "jenkins-persistent" are available in the "[[OpenShift_Concepts#.22openshift.22_Project|openshift]]" namespace. The "persistent" Jenkins will save its state between the pod restarts, and needs a [[OpenShift_Concepts#Persistent_Volume|persistent volume]] with sufficient storage space to be available at the time of the installation. | |||
oc -n openshift get templates | grep jenkins | oc -n openshift get templates | grep jenkins | ||
Revision as of 18:46, 8 December 2017
External
- https://docs.openshift.com/container-platform/latest/using_images/other_images/jenkins.html
- https://blog.openshift.com/cicd-with-openshift/
Internal
Overview
This article aggregates concepts related to the implementation of CI/CD pipelines in OpenShift. OpenShift relies on Jenkins to execute the core pipeline logic - pipeline is a Jenkins concept. Thus, Jenkins instances are deployed and integrated with OpenShift. Details related to how to integrate Jenkins with OpenShift are discussed in the Jenkins Integration section. Jenkins pipelines are exposed natively in OpenShift as pipeline builds.
Jenkins Integration
Jenkins Images and Templates
OpenShift provides a certified Jenkins container image, developed under https://github.com/openshift/jenkins repository. OpenShift also comes with two standard templates that use this image to create Jenkins infrastructure objects. The "jenkins-ephemeral" and "jenkins-persistent" are available in the "openshift" namespace. The "persistent" Jenkins will save its state between the pod restarts, and needs a persistent volume with sufficient storage space to be available at the time of the installation.
oc -n openshift get templates | grep jenkins jenkins-ephemeral Jenkins service, without persistent storage.... jenkins-persistent Jenkins service, with persistent storage....
OpenShift Jenkins Plugins
Jenkins is ultimately the application that drives the pipeline logic so it first need to be told what to do, via its Groovy pipeline syntax, and then it needs to execute the actions, and while doing so, it needs to access and modify OpenShift resources. All these are implemented via a series of plugins, described below:
OpenShift Plugin for Jenkins Plugin (jenkins-plugin)
This is the oldest Jenkins/OpenShift integration plugin, which executes inside Jenkins and implements a series of REST flows that interface with the OpenShift master server via its exposed API. This plugin does not require the oc binary to be present on the host that executes the plugin logic.
OpenShift Jenkins Pipeline DSL Plugin (jenkins-client-plugin)
This plugin provides a Jenkins pipeline DSL syntax for interactions with OpenShit. This plugin needs the oc binary to be present on the nodes executing the script. The plugin seems to be newer than the OpenShift Plugin for Jenkins Plugin (jenkins-plugin).
jenkins-sync-plugin
This plugin keeps OpenShift build configuration and build objects in sync with jobs and builds managed by the OpenShift-integrated Jenkins instances.
The plugin insures that any changes operated on OpenShift pipeline build configuration is propagated to the Jenkins job with the same name. When an OpenShift user triggers a build based on a pipeline build configuration, the plugin starts the corresponding Jenkins job. While the Jenkins build that is associated with the job is running, any changes in the build are replicated in the corresponding OpenShift build object. The plugin also examine ConfigMaps looking for XML documents that correspond to Kubernetes plugin pod templates, and changes the configuration of the Kubernetes plugin to add, edit or remove pod templates based on those found in the ConfigMaps. The plugin monitors changes in image streams labeled with "role=jenkins-slave" and image stream tags with a "role=jenkins-slave" annotation and updates the Kubernetes plugin pod templates accordingly.
jenkins-openshift-login-plugin
Kubernetes Plugin
The Kubernetes plugin is a Jenkins extension that uses a Kubernetes cluster to dynamically provision Jenkins agents, use them to run builds and then dispose of them. It does do by using Kubernetes scheduling mechanism to optimize the load. The Jenkins image that ships with OpenShift comes with the Kubernetes plugin pre-installed.