Setting Up Jenkins with Reverse Proxy, Domain, and SSL Certification

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Introduction

Jenkins is a popular open-source automation server used for CI/CD pipelines. To enhance its security and accessibility, setting up a reverse proxy, assigning a domain, and securing it with an SSL certificate is essential. This guide will walk you through installing Jenkins, configuring Nginx as a reverse proxy, and applying an SSL certificate using Let's Encrypt.

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Step 1: Install Jenkins

Jenkins requires Java to run. Install OpenJDK 17 and Jenkins on a Debian-based system using the following steps:

Install Java

sudo apt update -y
sudo apt install fontconfig openjdk-17-jre -y

Verify Java installation:

java -version

Install Jenkins

Follow the official Jenkins installation guide:

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-get update -y
sudo apt-get install jenkins

Start Jenkins

sudo systemctl enable jenkins
sudo systemctl start jenkins
sudo systemctl status jenkins

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Step 2: Install and Configure Nginx as a Reverse Proxy

Nginx is a high-performance web server that can serve as a reverse proxy for Jenkins.

Install Nginx

sudo apt install nginx -y
sudo service nginx start
sudo systemctl enable nginx
sudo systemctl status nginx

Verify the installation by entering your server's public IP in a browser. The default Nginx welcome page should appear.

Configure Nginx for Jenkins

Create a new Nginx server block configuration:

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

Add the following configuration:

server {
    listen 80;
    server_name jenkins.example.com; # Replace with your domain

    location / {
        proxy_pass http://localhost:8080; # Jenkins is running on default port
        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;
    }

    location ~ /\. {
        deny all;
    }
}

Enable the configuration:

sudo ln -s /etc/nginx/sites-available/jenkins /etc/nginx/sites-enabled/

Test and Restart Nginx

sudo nginx -t
sudo systemctl restart nginx

Now, access Jenkins via http://jenkins.example.com.

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Step 3: Apply SSL Certificate

To secure Jenkins with SSL, install Certbot and configure SSL.

Install Certbot

sudo apt install python3-certbot-nginx
certbot --version

Obtain and Apply SSL Certificate

Replace xyz.com with your actual domain:

certbot --nginx -d xyz.com

Follow the on-screen instructions to complete the SSL setup.

Renew SSL Certificate Automatically

sudo certbot renew --dry-run

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Conclusion

By following this guide, you've successfully set up Jenkins with a reverse proxy, assigned a domain, and secured it with SSL certification. This setup enhances security and allows easy access to your Jenkins instance using a domain name with HTTPS.

For further reading, check out the official Jenkins documentation. Happy DevOps!