Jenkins as a Code (JCasC) Example

This example implements Jenkins as a code using Jenkins Configuration as Code Plugin.

Prerequisite

• Docker
• Linux / Mac machine with bash
• Understanding of configuring Jenkins controllers and agents

Objective of this demo is to demonstrate capability to run Jenkins controller and agent as docker image (instead running them on VM).

Features

This example uses official Jenkins docker images jenkins/jenkins and jenkins/inbound-agent as base images.

Implemented features

• Script to create Jenkins controller docker image
• configuration of Jenkins through jenkins.yaml
  • Two users setup admin and readonly (password same as username)
  • Access control for users
  • Two jobs setup for running through JOB DSL Plugin
  • Permanent node setup docker-agent2
  • Two views for UI and Microservices
  • Global credential setup for git using ssh
• Installation of required plugins (plugins.txt)
• Script to create Jenkins Agent docker image
• Shell scripts to build run controller and agent on linux/mac

Quick Start - Run Jenkins

Start the Jenkins controller

docker run -p  8080:8080 -p 50000:50000 -e CASC_JENKINS_CONFIG=/usr/share/jenkins/ -e MY_JENKINS_URL="http://host.docker.internal:8080/"  mandarnilange/jenkins-controller

Go to Jenkins web controller at http://localhost:8080, and identify secret for docker-agent2.

Start Jenkins Agent

docker run --init -e JENKINS_URL=http://host.docker.internal:8080 -e JENKINS_AGENT_NAME=docker-agent2 -e JENKINS_AGENT_WORKDIR=/home/jenkins/agent -e JENKINS_SECRET=<Secret from master> mandarnilange/jenkins-inbound-agent

Go to Jenkins controller web and confirm agent is connected and jobs created to confirm job installation.

In case, you want to build yourself from source and run locally then follow next section.

Build and Run Locally From Code

Jenkins Controller

Following command will copy jenkins.yaml, copy InitialConfig.groovy, install plugins and build controller image mandarnilange/jenkins-controller

$ cd jenkins-controller
$ ./buildControllerImage.sh 

Run controller image after setting up environemnt variables in controller.env (no changes needed in case run on Mac/linux)

• CASC_JENKINS_CONFIG for Configuration as Code plugin config file location
• MY_JENKINS_URL to indicate host on which controller is running
• SSH_PRIVATE_KEY set private key for access git/bitbucket private repository

$ ./startController.sh

Jenkins Agent

Following will build agent image mandarnilange/jenkins-inbound-agent

$ cd jenkins-agent
$ ./buildAgentImage.sh

Run agent image after setting up environment variables in agent.env (no changes needed in case run on Mac/linux)

• JENKINS_URL URL of controller
• JENKINS_SECRET Secret to be taken from docker-agent2 node configuration on cluster
• JENKINS_AGENT_NAME Name of agent configured in controller
• JENKINS_AGENT_WORKDIR work directory for agent

$ cd jenkins-agent
$ ./runAgent.sh

Next Steps

You can extend this implementation - some key next steps that can be taken

• Add more users: update jenkins.yaml and recreate image
• Setup more jobs: update jenkins.yaml and recreate image
• Setup external volume for persistent storage: update startController.sh
• Access private git repository: setup SSH_PRIVATE_KEY before starting controller
• Install additional plugins: udpate plugins.txt and recreate image
• Add more agents: update jenkins.yaml and recreate image

Happy Learning!

References

mandarnilange/jenkins-controller

mandarnilange/jenkins-inbound-agent

Jenkins Configuration as Code Plugin

DSL plugin docmentation

Git repo - Jenkins as Code for this example