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Jenkins Tutorial

Jenkins is an open-source automation server used to build, test, and deploy software. It supports Continuous Integration (CI) and Continuous Deployment (CD), making it a popular tool in DevOps.

1. Installing Jenkins​

Step 1: Install Java​

Jenkins requires Java (Java Development Kit, JDK) to run.

On Ubuntu​

sudo apt update
sudo apt install openjdk-11-jdk

Step 2: Install Jenkins​

Follow the instructions from the Jenkins website for your operating system.

On Ubuntu​

wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo apt-key add -
sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
sudo apt update
sudo apt install jenkins

Start Jenkins with:

sudo systemctl start jenkins

Access Jenkins​

Visit http://localhost:8080 in your browser to access Jenkins.

2. Setting Up Jenkins​

Unlocking Jenkins​

  1. When you first access Jenkins, you’ll be asked for an admin password.

  2. Locate the password in /var/lib/jenkins/secrets/initialAdminPassword:

    sudo cat /var/lib/jenkins/secrets/initialAdminPassword

  3. Enter this password to unlock Jenkins.

Installing Suggested Plugins​

After unlocking, Jenkins will prompt you to install suggested plugins. This will include commonly used plugins.

3. Creating Your First Job​

  1. Click on New Item on the Jenkins dashboard.
  2. Enter a name for your project and select Freestyle project.
  3. Configure the job with various build steps, triggers, and post-build actions.

Example Build Step​

In Build > Execute Shell, you can add a shell command:

echo "Hello, Jenkins!"

Save the job and click Build Now to run it.

4. Configuring Source Control with Git​

Jenkins integrates with source control systems like Git.

  1. In your job configuration, scroll to Source Code Management.
  2. Select Git and enter the repository URL.
  3. You may need to provide credentials for private repositories.

5. Adding Build Triggers​

Build triggers allow Jenkins to automatically start jobs based on events.

Common Triggers​

  • Poll SCM: Checks for code changes at specified intervals.
  • Build Periodically: Runs jobs at scheduled times.
  • GitHub Hook Trigger: Starts a build when there are commits to a GitHub repository.

6. Pipeline as Code​

Jenkins Pipelines allow you to define CI/CD workflows using code, usually stored in a Jenkinsfile.

Creating a Pipeline​

  1. Click New Item > Pipeline.
  2. Define the pipeline in the Pipeline section using Scripted or Declarative syntax.

Example Declarative Pipeline​

pipeline {
    agent any

    stages {
        stage('Build') {
            steps {
                echo 'Building...'
            }
        }
        stage('Test') {
            steps {
                echo 'Testing...'
            }
        }
        stage('Deploy') {
            steps {
                echo 'Deploying...'
            }
        }
    }
}

7. Jenkinsfile Example for Git Integration​

Place a Jenkinsfile in the root of your Git repository to use it with Jenkins.

pipeline {
    agent any
    stages {
        stage('Clone Repository') {
            steps {
                git 'https://github.com/your-repo/example.git'
            }
        }
        stage('Build') {
            steps {
                echo 'Building the project...'
            }
        }
    }
}

Configure the job to pull the Jenkinsfile from the repository.

8. Installing Plugins​

Jenkins has an extensive plugin ecosystem.

  1. Go to Manage Jenkins > Manage Plugins.
  2. Search for plugins like Git, GitHub Integration, Slack Notifications, etc.
  3. Click Install and restart Jenkins if prompted.

9. Setting Up Notifications​

Email Notifications​

  1. Go to Manage Jenkins > Configure System.
  2. Set up an SMTP server and email configuration.

Slack Notifications​

  1. Install the Slack Notification plugin.
  2. Go to your job configuration, scroll to Post-build Actions and add Slack Notifications.

10. Backing Up Jenkins​

Jenkins stores its configuration and job data in /var/lib/jenkins (or similar).

  • Backing up: Regularly back up the JENKINS_HOME directory.
  • Restoring: Replace JENKINS_HOME with your backup and restart Jenkins.

Summary​

This tutorial covered Jenkins basics:

  1. Installing Jenkins and setting up the server.
  2. Creating jobs and configuring source control with Git.
  3. Setting up pipelines and using the Jenkinsfile.
  4. Installing plugins and configuring notifications.

Jenkins is a powerful tool for automating CI/CD workflows, supporting many integrations to streamline software development.

Content Review​

The content in this repository has been reviewed by chevp. Chevp is dedicated to ensuring that the information provided is accurate, relevant, and up-to-date, helping users to learn and implement programming skills effectively.

About the Reviewer​

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