OpenShift CI/CD Operations - Collocated Persistent Jenkins Set Up

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Overview

This is the procedure to deploy a persistent Jenkins instance in the same project as the application that intends to use it, and configure it to build and deploy the application.

Pre-Requisites

Create the project to host the Jenkins instance and the application instance: 

oc new-project os3-jenkins-example

Provision a 2Gi persistent volume to be used by Jenkins.

Verify that the persistent Jenkins template is available. 

 oc get template/jenkins-persistent -n openshift

Deploy Persistent Jenkins

oc new-app \
  -p VOLUME_CAPACITY=2Gi \
  -p MEMORY_LIMIT=1Gi \
  -e INSTALL_PLUGINS=analysis-core:1.92,findbugs:4.71,pmd:3.49,checkstyle:3.49,dependency-check-jenkins-plugin:2.1.1,htmlpublisher:1.14,jacoco:2.2.1,analysis-collector:1.52 \
 jenkins-persistent

By default, the template enables OAuth integration.

After the deployment completes, you should be left with a Jenkins pod that can be accessed with the public URL https://jenkins-os3-jenkins-example.apps.openshift.novaordis.io, using OpenShift credentials, since OAuth integration is supposed to be active.

The installation procedure should have created a "system:serviceaccount:os3-jenkins-example:jenkins" service account and given it the "edit" role. Jenkins will authenticate as "system:serviceaccount:os3-jenkins-example:jenkins" to the OpenShift master and will need these permissions to perform its functions. For more security details, see OpenShift CI/CD Security Considerations.

Various configuration adjustments can be performed after installation:

Adjust Readiness Probe Timeout

 oc set probe dc jenkins --readiness --initial-delay-seconds=500

The same effect can be achieved with 

oc edit dc/jenkins

and changing spec/template/spec/containers/name=jenkins/livenessProbe/initialDelaySeconds

Adjust Memory

oc set resources dc/jenkins --limits=memory=3Gi

Deploy a Sample Application

This is a standard node.js HelloWorld OpenShift example: https://raw.githubusercontent.com/openshift/origin/master/examples/jenkins/application-template.json

If can be downloaded locally, inspected, edited, and then instantiated: 

oc new-app -f ./application-template.json

Without additional configuration, the application will create all OpenShift objects required to do a source-to-image build and to deploy and expose the final artifact as https://nodejs-helloworld-sample-os3-jenkins-example.apps.openshift.novaordis.io. However, neither the build nor the deployment start automatically, as the application "expects" its release procedure to be driven by Jenkins.

Configure a Jenkins Project

New Item -> Freestyle project -> "os3-jenkins-example" -> Save.

Source Code Management: None.

Build:

  • Scale OpenShift Deployment:

Then name of the DeploymentConfig to scale: frontend

The number of replicas to scale the deployment to: 0

Verify whether the specified number of replicas are up: No

  • Trigger OpenShift Build

The name of the BuildConfig to trigger: frontend

  • Trigger OpenShift Deployment

The name of the DeploymentConfig to trigger a deployment of: frontend

  • Verify OpenShift Service

The name of the Service to verify: frontend

  • Tag OpenShift Image

The name of the ImageStream for the current image tag: origin-nodejs-sample

The name of the current image tag or actual image ID: latest

The name of the ImageStream for the new image tag: origin-nodejs-sample

The name of the new image tag: prod

  • Verify OpenShift Deployment:

The name of the DeploymentConfig to validate: frontend-prod

The number of replicas you expect the deployment to scale to: 1

Save

Build

The build should trigger an OpenShift build of the application, wait for the build to result in a deployment, confirm that the new deployment works, and then tag the image for production. Tagging the image will trigger the production deployment, which was configured in dc/frontend-prod. In the end, we should get a "frontend" and a "frontend-prod" being deployed and running (for the "prod" pod, the route must be created manually).

Use of Kubernetes Plugin

The Jenkins instance was used so far without a Kubernetes plugin. This means ?what?.

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