How Components Interact

1. Controller Image (istiaka2i/create-deploy:latest)

• Built from the provided Dockerfile.
• Contains the compiled Go controller (main.go).
• When run, this image connects to the Kubernetes API and creates:
  • A Deployment (go-book-app) that runs the book application container (istiaka2i/bookapp:v1.0).
  • A NodePort Service (go-book-service) to expose the app.

2. Controller Pod (go-book-app-controller.yaml)

• Defines a Pod that runs the controller image.
• Uses the go-book-app-sa ServiceAccount for RBAC permissions.
• When this Pod starts, it triggers the controller logic:
  • The controller creates the Deployment and Service in the cluster.

3. Book App Deployment (main.go logic)

• Created by the controller Pod.
• Runs the book application image: istiaka2i/bookapp:v1.0.
• The Deployment ensures two replicas of the app are running.

4. NodePort Service (main.go logic)

• Also created by the controller Pod.
• Exposes the book app on port 4000 (mapped to container port 8080) and NodePort 30080.

Flow Diagram

[Controller Image: create-deploy]
           |
           v
[Controller Pod: go-book-app-controller.yaml]
           |
           v
[Controller Logic: main.go]
           |
           v
[Creates Deployment: go-book-app] ----> [Runs bookapp:v1.0]
           |
           v
[Creates Service: go-book-service] ----> [Exposes app via NodePort]

Summary

• You build and deploy the controller image.
• The controller Pod runs and triggers the creation of the book app Deployment and Service.
• The book app image is pulled and run by the Deployment, and exposed by the Service.

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Quickstart Commands

1. Build Controller Image

   docker build -t istiaka2i/create-deploy:latest .

2. Apply RBAC

   kubectl apply -f rbac.yaml

3. Deploy Controller Pod

   kubectl apply -f go-book-app-controller.yaml

4. Check Resources

   kubectl get pods
   kubectl get deployments
   kubectl get services

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This workflow ensures that the controller image, when run as a Pod, automatically provisions your book app and exposes it in the cluster.