What is Jenkins?

Jenkins is an open-source automation server widely used in software development to automate tasks related to building, testing, and deploying applications. It’s a cornerstone tool in DevOps practices, enabling Continuous Integration (CI) and Continuous Delivery (CD)..

How Jenkins Works

1. Master-Node Architecture

   • Master Node: Coordinates the build and deployment processes. It handles scheduling and monitoring jobs.

   • Worker Nodes: Execute the builds. You can scale Jenkins by adding more nodes to handle heavy workloads.

2. Job Configuration

   • Jobs define tasks like pulling code from a repository, running tests, and deploying applications.

   • Jobs can be triggered manually, on a schedule, or automatically (e.g., when code is pushed to GitHub).

3. Continuous Integration/Delivery

   • CI: Jenkins automatically builds and tests code whenever developers commit changes, ensuring issues are caught early.

   • CD: Jenkins deploys applications to production or staging environments in an automated, repeatable manner.

Setting up Jenkins on EC2 instance

Step 1: Launch an EC2 Instance

Launch EC2 instance and configure it as Jenkins Master. Edit the inbound traffic rule to only allow custom TCP port 8080

Step 2: Install Java

sudo apt update
sudo apt install openjdk-17-jre

After running the commands, verify the Java version to ensure it’s installed correctly.

Step 3: Install Jenkins

curl -fsSL https://pkg.jenkins.io/debian/jenkins.io-2023.key | sudo tee \
  /usr/share/keyrings/jenkins-keyring.asc > /dev/null
echo deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] \
  https://pkg.jenkins.io/debian binary/ | sudo tee \
  /etc/apt/sources.list.d/jenkins.list > /dev/null
sudo apt-get update
sudo apt-get install jenkins

• Downloads and store Jenkins' GPG key securely.

• Configures your system to use the Jenkins repository, ensuring future package installations and updates are fetched from this source.

• Ensures package security by requiring signatures verified with the stored GPG key

• Refresh Package Index using apt-get update: It downloads the latest lists of packages and their versions from the repositories specified in the /etc/apt/sources.list file and files in /etc/apt/sources.list.d/.

• Install Jenkins

Step 4

Login to Jenkins using below url

http://<ec2-instance-publicip>:8080 [You can get the ec2-instance-public-ip-address from your AWS EC2 console page]

After you login to Jenkins - Run the command to copy the Jenkins Admin Password - sudo cat /var/lib/jenkins/secrets/initialAdminPassword - Enter the Administrator password

Step 5

Install Suggested plugins

Step 6

Create Admin User

Jenkins Installation is Successful. You can now starting using the Jenkins

Step 7

Install the Docker Pipeline plugin in Jenkins

• Log in to Jenkins.

• Go to Manage Jenkins > Manage Plugins.

• In the Available tab, search for "Docker Pipeline".

• Select the plugin and click the Install button.

• Restart Jenkins after the plugin is installed.

  

Step 8

Docker Slave Configuration

Run the below command to Install Docker

sudo apt update
sudo apt install docker.io

Step 9

Grant Jenkins user and Ubuntu user permission to docker deamon

sudo su - 
usermod -aG docker jenkins
usermod -aG docker ubuntu
systemctl restart docker

Once you are done with the above steps, restart Jenkins.

http://<ec2-instance-public-ip>:8080/restart

The docker agent configuration is now successful.