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Anohba Jehad
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Meet Jenkins: A Guide to Automation

·727 words·4 mins
Jenkins Plugins Pipeline Shell CI/CD
Table of Contents

What is Jenkins?
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Jenkins is an open-source automation tool written in Java. It helps developers build, test, and deploy their software automatically, making Continuous Integration (CI) and Continuous Delivery (CD) possible.

CI: Continuous Integration
Automatically building and testing code whenever changes are pushed. 
CD: Continuous Delivery
 Automatically deploying/releasing the code to production or staging. 

Together, CI/CD makes your workflow faster, safer, and hands-free.

In simple terms:

Jenkins watches your code and runs jobs (like building or testing) whenever you push changes — saving you tons of manual work.

Jenkins is a server. It’s a program you install on a machine (your own computer, a VPS, or cloud) that:

  • • Runs 24/7.
  • • Waits for code changes (like GitHub push).
  • • Does tasks you define (build, test, deploy).
  • • Reports the results.

Why Use Jenkins?
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  • Automate repetitive tasks like testing and deploying.
  • Supports a wide range of plugins and tools.
  • Saves time in large teams and projects.
  • Detects bugs early by testing code regularly.
  • Web-based interface for managing jobs easily.

Key Concepts to Know
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TermMeaning
Job / ProjectA task that Jenkins runs (e.g., build, test).
BuildThe process of compiling code, running scripts, etc.
PipelineA set of steps that automate the process from build to deployment.
Node / AgentA machine that runs Jenkins jobs (can be remote).
PluginExtension that adds new features to Jenkins.

How to Install Jenkins on Ubuntu (Beginner-Friendly)
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Step 1: Install Java
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command screenshot

Then run:

command screenshot

Check the Java version:

command screenshot

Step 2: Add Jenkins Repository
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command screenshot

Step 3: Install Jenkins
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command screenshot

Step 4: Start and Enable Jenkins
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command screenshot
command screenshot

Then check the status if its active:

command screenshot

Step 5: Open Jenkins in Browser
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Visit: http://localhost:8080

To unlock Jenkins, run:

command screenshot

Paste the password in your browser when prompted.

Proceed with the steps required and it will get you to the main Jenkins page:

command screenshot

Setting Up Your First Job (Freestyle Project)
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  1. Go to Dashboard > New Item

  2. Choose Freestyle project and give it a name

  3. In Build Steps, choose:

  • Execute shell for Linux commands

  • Or Execute Windows batch command for Windows

  1. Add your script like:
echo "Hello from Jenkins!"
  1. Click Save, then Build Now

Jenkins will run your job and show you output in the Console Output.

Jenkins Pipeline (Scripted Automation)
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Create a new Pipeline job and use the following example script:

pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                echo 'Building the project...'
            }
        }
        stage('Test') {
            steps {
                echo 'Running tests...'
            }
        }
        stage('Deploy') {
            steps {
                echo 'Deploying the project...'
            }
        }
    }
}

Integrating Jenkins with Git (or GitLab)
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Jenkins works best when connected to a version control system like GitHub or GitLab. This allows Jenkins to:

  • Watch for new code pushes
  • Automatically trigger builds and tests
  • Pull code into your pipeline jobs

Example (GitLab):
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  1. Install the Git Plugin (if not already).
  2. Create a Personal Access Token in GitLab.
  3. In Jenkins, go to Credentials > Add Credentials and enter your GitLab token.
  4. Create a new Pipeline or Freestyle job.
  5. Under Source Code Management, choose Git and paste your GitLab repo URL.

Now every time you push to GitLab, Jenkins can respond automatically.

Useful Plugins to Explore
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PluginPurpose
Git PluginIntegrate with Git repositories
GitHub IntegrationTrigger builds from GitHub pushes
Pipeline PluginUse Jenkinsfile for automation workflows
Email ExtensionSend notifications based on build status
Docker PluginBuild and run Docker containers via Jenkins

Final Thoughts
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Jenkins is like your project manager robot — it does the boring and repetitive tasks so you can focus on writing code.

With its powerful CI/CD pipelines, plugin ecosystem, and integration options, Jenkins is trusted by teams all over the world to ship better software — faster.

Once you’re comfortable with the basics, explore more advanced topics like:

  • Shared Libraries (DRY pipelines)
  • Blue Ocean (visual pipeline editor)
  • Dockerized builds
  • Jenkins + Kubernetes or AWS for cloud deployments
  • Jenkins + GitLab CI integration

Jenkins is not just a tool, it’s the engine behind modern DevOps.

Jenkins Installation Commands
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sudo apt update
sudo apt install openjdk-17-jdk
java -version
wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo tee /usr/share/keyrings/jenkins-keyring.asc > /dev/null
echo deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] https://pkg.jenkins.io/debian-stable binary/ | sudo tee /etc/apt/sources.list.d/jenkins.list > /dev/null
sudo apt update
sudo apt install jenkins
sudo systemctl enable jenkins
sudo systemctl start jenkins
sudo systemctl status jenkins
sudo cat /var/lib/jenkins/secrets/initialAdminPassword