In this Jenkins script, we are performing several tasks to build and deploy an application using Docker, AWS ECR, Terraform, and Kubernetes. Here's a breakdown of the steps in a more understandable format:

Step 1: Build Docker Image and Push to AWS ECR

• Start by building a Docker image.
• The image is then pushed to an AWS Elastic Container Registry (ECR).

Step 2: Create AWS Resources

Under the "CREATE ENVIRONMENT" section, we set up AWS resources:

• Configure the AWS environment variables such as AWS_DEFAULT_REGION, AWS_CREDENTIALS, and PATH.

• Create an AWS ECR repository using the aws ecr create-repository command.

• Create an AWS S3 bucket using the aws s3 mb command.

• Create an AWS DynamoDB table using the aws dynamodb create-table command. Step 3: AWS ECR Authentication

• Use AWS CLI commands to authenticate with AWS ECR from within our Jenkins pipeline script.

Step 4: Terraform Initialization and Deployment

• Use Terraform to initialize and deploy infrastructure.
• Terraform reads configuration files from the terraform/ecr_registry directory.
• The Terraform outputs (registry_id, repository_name, repository_url) are captured for later use.

Step 5: Build and Deploy Docker Image

• Build a Docker image from the Dockerfile.
• The image is tagged with the repository name and build ID.
• The Docker image is pushed to the ECR repository.
• Clean up by removing local Docker images.

Step 6: Kubernetes Deployment

• Configure the Kubernetes credentials and server URL.
• A Docker registry secret is created for accessing the ECR repository.
• Apply Kubernetes manifests (k8sbook.yaml and kjavaapps.yaml) using kubectl apply.
• Before applying kjavaapps.yaml, we use envsubst to substitute environment variables in the YAML file.

Additional Notes:

• You have defined functions for creating AWS resources (ECR, S3 bucket, DynamoDB) and retrieving Terraform paths.
• You use a Jenkins agent to run our pipeline stages.
• The Jenkins slave is set up to communicate with Kubernetes.
• You have configured Kubernetes credentials for Jenkins using kubectl get secrets.
• You have to establish a tunnel for Jenkins to communicate with Kubernetes.
• Instead of a pod template, we use a Kubernetes manifest for defining the build pod.
• The Docker image used in the build pod contains AWS, Docker, Python, and kubectl.
• The Kubernetes cluster information is obtained using kubectl cluster-info.

Overall, this Jenkins script automates the process of building, deploying, and configuring various AWS and Kubernetes resources for your application, providing a streamlined CI/CD pipeline.