How to Install and Configure Jenkins on AlmaLinux 9

Estimated reading: 2 minutes 469 views

Introduction

Jenkins is an open-source automation server widely used for Continuous Integration and Continuous Delivery (CI/CD). It helps automate building, testing, and deploying applications, making development workflows faster and more reliable.

In this guide, you will learn how to install and configure Jenkins on AlmaLinux 9 step by step, along with verification and troubleshooting tips.

Prerequisites

Before starting, make sure you have:

AlmaLinux 9 server installed
A user with sudo privileges
Minimum 2 GB RAM (recommended)
Internet connection
Firewall access to port 8080

Step 1: Update the System

Update all system packages:

sudo dnf update -y

Step 2: Install OpenJDK

Jenkins requires Java to run. Install OpenJDK 21:

sudo dnf install java-21-openjdk -y

Verify Java Installation

java -version

Step 3: Add Jenkins Repository Key

Import the Jenkins GPG key:

sudo rpm --import https://pkg.jenkins.io/redhat-stable/jenkins.io-2023.key

Step 4: Add Jenkins Repository

Add the official Jenkins repository:

sudo wget -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat-stable/jenkins.repo

Step 5: Install Jenkins

Install Jenkins package:

sudo dnf install jenkins -y

Step 6: Start Jenkins Service

Start Jenkins:

sudo systemctl start jenkins

Step 7: Enable Jenkins on Boot

Enable Jenkins to start automatically:

sudo systemctl enable jenkins

Step 8: Check Jenkins Status

Verify Jenkins is running:

sudo systemctl status jenkins

Step 9: Retrieve Initial Admin Password

Get the default admin password:

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

Step 10: Access Jenkins Web Interface

Open your browser and go to:

http://your-server-ip:8080

Initial Setup

Enter the admin password

Click Install suggested plugins

Wait for installation

Create admin user

Set Jenkins URL

Click Start using Jenkins

Troubleshooting

1. Jenkins not starting

Check service status:

sudo systemctl status jenkins

Check logs:

sudo journalctl -u jenkins -xe

2. Cannot access Jenkins (port 8080)

Check firewall:

sudo firewall-cmd --list-ports

Check port:

ss -tulnp | grep 8080

3. Java issues

Ensure Java is installed:

java -version

Security Recommendations

Do not expose port 8080 directly to the internet
Use Nginx reverse proxy
Enable HTTPS (SSL)
Restrict access by IP or VPN
Regularly update Jenkins and plugins

Conclusion

You have successfully installed and configured Jenkins on AlmaLinux 9. Jenkins is now ready to be used for automating your CI/CD pipelines, integrating with Git repositories, and managing deployments.

For production environments, it is recommended to enhance security using a reverse proxy (Nginx) and SSL certificates.