Jenkins is the most widely used open-source automation server. It supports building, testing, and deploying software through pipelines defined as code (Jenkinsfile). This guide installs Jenkins LTS on Ubuntu 26.04 LTS and secures it behind Nginx with HTTPS.

Tested and valid on:

Ubuntu 26.04 LTS

Prerequisites

Ubuntu 26.04 LTS with Java 21+ (OpenJDK)
Nginx installed
Ports 80 and 443 open in UFW

Step 1 – Install Java

sudo apt update
sudo apt install openjdk-21-jdk -y
java -version

Step 2 – Add the Jenkins Repository

sudo wget -O /usr/share/keyrings/jenkins-keyring.asc 
  https://pkg.jenkins.io/debian-stable/jenkins.io-2023.key
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

Step 3 – Install Jenkins LTS

sudo apt install jenkins -y
sudo systemctl start jenkins
sudo systemctl enable jenkins
sudo systemctl status jenkins

Step 4 – Retrieve the Initial Admin Password

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

Step 5 – Configure Nginx Reverse Proxy

sudo nano /etc/nginx/sites-available/jenkins

Add:

server {
    listen 80;
    server_name jenkins.example.com;
    location / {
        proxy_pass http://localhost:8080;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

sudo ln -s /etc/nginx/sites-available/jenkins /etc/nginx/sites-enabled/
sudo nginx -t && sudo systemctl reload nginx

Step 6 – Add SSL

sudo certbot --nginx -d jenkins.example.com

Step 7 – Complete Setup via Browser

Visit https://jenkins.example.com. Enter the initial admin password, install suggested plugins, and create the first admin user.

Conclusion

Jenkins is installed and secured on Ubuntu 26.04 LTS. Create your first pipeline by adding a Jenkinsfile to your repository and configuring a Jenkins job to pull from it.

How to Install Jenkins on Ubuntu 26.04