CI/CD Workflow with Jenkins, Docker, and AWS EC2

Continuous Integration and Continuous Deployment (CI/CD) workflows have transformed the way we write and ship code. This guide explores how to configure a Jenkins server to fetch the latest code changes from a Git repository using webhooks, build Docker images, and run application containers on an AWS EC2 instance.

Prerequisites

• AWS free-tier account (or another cloud provider with minor adjustments)
• GitHub repository (front-end or back-end code)
• Basic familiarity with Linux commands and Bash scripting

Server Setup: EC2 Instance

For this article, an AWS EC2 instance will be used to host the Jenkins server and run Docker containers. However, the steps are applicable to other cloud providers or even physical servers.

Instead of manually provisioning servers via the AWS UI, Terraform can be used. Example Terraform configuration is available here: [Terraform Code - GitHub]

Setting Up GitHub SSH Key

To automate code fetching and building:

1. Connect to the EC2 instance and generate an SSH key:

   ssh-keygen
   

2. Display the public key:

   cat /home/ubuntu/.ssh/id_rsa.pub
   

3. Copy and add the public key to GitHub Settings > SSH and GPG Keys as an authentication key.

Jenkins Server Configuration

After launching the EC2 instance, install the required tools:

• Jenkins (on Ubuntu 22.04)
• Git, Node.js, and npm
• Docker

Note: Pre-configured installation scripts are available here: [Automated Tools Install Script]

Accessing Jenkins

Ensure port 8080 is open, then access Jenkins via:

http://instance.public_ip:8080

Set up an admin user, install recommended plugins, and proceed to the dashboard.

Configuring a Jenkins Pipeline

1. Create a Freestyle Jenkins Pipeline and add the GitHub repository.
2. Set Git credentials using the SSH private key:

   cat /home/ubuntu/.ssh/id_rsa
   

3. Go to Jenkins Dashboard > Manage Jenkins > Credentials, and add an SSH private key.

Automating Docker Build and Deployment

Instead of manually running Docker commands, automate the process within Jenkins:

#!/bin/bash
docker rm -f $(docker ps -aq)
docker build -t yourappname .
docker run -d --name yourappname -p PORT:PORT yourappname:latest
echo "Built and ran project on port ...."

Run the pipeline and verify that the application is accessible at:

http://instance.public_ip:PORT

Setting Up GitHub Webhook

To fully automate deployment:

1. Install the GitHub Integration Plugin in Jenkins.
2. Enable GitHub hook trigger for GIT SCM polling in the pipeline configuration.
3. Add a webhook in GitHub Repo Settings > Webhooks with the following payload URL:

   http://instance.public_ip:8080/github-webhook
   

4. Save the webhook and push changes to the repository to test automation.

Conclusion

By implementing this CI/CD workflow, code changes are automatically fetched, built into Docker images, and deployed on an EC2 instance. This ensures efficient, reliable, and automated software delivery, improving both development speed and operational stability.