Introduction and Setup of Jenkins

Setup: Installation, Configuration, Jenkins UI, Master Slave Architecture, Backup and Restore

Learning Outcome

Core Concepts (Slide 6)

Step 1: Create an EC2 instance(Ubuntu)

• Select Ubuntu as the operating system

• Launch the EC2 instance successfully

• Connect to the instance using the terminal

Step 2: Install Java (Prerequisite for Jenkins)

Jenkins is a Java-based application, so Java must be installed before Jenkins.

Run the following command:

sudo apt install fontconfig openjdk-21-jre

Configure Security Group (Important)

• Edit the Inbound Rules of the security group

• Add a Custom TCP rule

• Set Port Range: 8080

• Set Source: 0.0.0.0/0 (Open to the internet)

This allows access to the Jenkins web interface through the browser.

Note for students:
Port 8080 is the default port used by Jenkins to access its dashboard.

This EC2 instance will act as the server where Jenkins will be installed.

Core Concepts (Slide 7)

After installation, verify Java:

This confirms that Java is installed and working correctly

Step 3: Prepare the System for Jenkins Installation

Before installing Jenkins, we need to:

• Add Jenkins official GPG key

• Add Jenkins package repository

This ensures Jenkins is installed from a trusted and official source.

java -version

Core Concepts (.....Slide N-3)

Step 4: Add Jenkins GPG Key

Run the following command:

This key verifies that Jenkins packages are authentic and not modified

Step 5: Add Jenkins Repository

Now add the Jenkins package source:

This step tells Linux where to download Jenkins from

sudo wget -O /etc/apt/keyrings/jenkins-keyring.asc \
https://pkg.jenkins.io/debian-stable/jenkins.io-2026.key

echo "deb [signed-by=/etc/apt/keyrings/jenkins-keyring.asc] \
https://pkg.jenkins.io/debian-stable binary/" | sudo tee \
/etc/apt/sources.list.d/jenkins.list > /dev/null

Core Concepts (.....Slide N-3)

Step 6: After adding the Jenkins repository, we now install Jenkins and make sure its service is running correctly on the system

• sudo apt update

Updates the system package list

• sudo systemctl status jenkins

Shows Jenkins service status

• sudo systemctl start jenkins

Starts the Jenkins service

• sudo systemctl enable jenkins

Enables Jenkins at system startup

• sudo apt install jenkins

Installs Jenkins on the system

>>sudo apt update
>>sudo apt install jenkins
>>sudo systemctl enable jenkins
sudo systemctl start jenkins
sudo systemctl status jenkins

Core Concepts (.....Slide N-3)

Step 7: Access Jenkins in Browser

Open the browser inside your virtual machine and visit:

http://YourIPAddress:8080/

This opens the Jenkins web interface

Step 8: Locate Initial Administrator Password

When Jenkins starts for the first time, it asks for an Administrator Password

The UI shows a file path:

/var/lib/jenkins/secrets/initialAdminPassword

Step 9: Retrieve Administrator Password

Run this command in the terminal:

cat /var/lib/jenkins/secrets/initialAdminPassword

This command displays the initial admin password

Step 10: Unlock Jenkins

• Copy the password from the terminal

• Paste it into the Jenkins UI

• Click Continue

Core Concepts (.....Slide N-3)

Step 11: Create Jenkins User

Set up:

• Username

• Password

• Email

This user will be used to log in to Jenkins

Step 12: Configure Jenkins URL

• For personal or learning use, keep the default URL

• In industry environments, DevOps/SRE teams usually customize this URL based on infrastructure needs

Click Save and Finish

Jenkins setup is now complete!

Jenkins UI

When we open Jenkins in a browser, the first screen we see is called the Jenkins Dashboard

The Jenkins dashboard is the main control panel of Jenkins

From here, we create jobs, run tasks and manage Jenkins settings

Jenkins UI

This dashboard is used to control & monitor everything that Jenkins does

Jenkins UI

Section

Description

Dashboard

New Item

Build History

Manage Jenkins

Jenkins logo

The home page of Jenkins

Used for configuration and settings

Shows past job runs

Used to create a new job

Clicking it always brings you back to home

Understanding the Master–Slave (Controller–Agent) Architecture

Jenkins follows a Controller–Agent architecture where:

The Controller decides what work needs to be done

The Agent performs the actual work

Earlier called Master–Slave, now professionally called Controller–Agent

What is Jenkins Controller (Master) ?

The Jenkins Controller is the main system that manages Jenkins

It is the brain of Jenkins

The controller does not perform heavy tasks, it only manages and controls

Controller responsibilities:

• Stores jobs and pipelines
• Manages users and permissions
• Assigns jobs to agents
• Displays build results on the dashboard

What is Jenkins Agent (Slave) ?

The Jenkins Agent is a worker machine

It performs the actual execution work

Agent responsibilities:

• Runs builds
• Executes commands
• Performs testing and deployment
• Sends results back to the controller

HOW does Master–Slave (Controller–Agent) Architecture work ?

A developer writes and pushes code

The controller displays the result

The agent sends the result back

The agent runs the build, test or deployment

The controller selects an agent

The Jenkins Controller receives the request

HOW does Master–Slave (Controller–Agent) Architecture work ?

Architecture Flow:

Developer → Jenkins Controller → Jenkins Agent → Result 

How does this architecture help in real companies?

Practical benefits:

• Multiple builds run in parallel
• Less load on the controller
• Faster and more reliable pipelines
• Easy to add more agents when workload increases

Industry usage:

One main controller server

Multiple agents for different environments (Linux, Windows, Docker & Cloud)

How does this architecture help in real companies?

In short:

WHY: To improve performance and scalability

WHAT: Controller manages, Agents execute

HOW: Controller assigns work, Agent completes it

Summary

Which platform is mainly used for professional networking and B2B marketing ?

Which platform is mainly used for professional networking and B2B marketing ?