This project demonstrates how to deploy a simple Flask application that displays "Hello, World!" using Kubernetes. It covers the process of creating a Flask app, containerizing it with Docker, and deploying it to a Kubernetes cluster.

• Docker installed and configured
• Kubernetes cluster (local or cloud-based)
• kubectl command-line tool installed and configured
• Python 3.9 or later

kubernetes-flask-hello-world/
├── app.py
├── Dockerfile
├── requirements.txt
└── kubernetes-deployment.yaml

1. Clone the repository:

   git clone <repository-url>
   cd kubernetes-flask-hello-world

2. Build the Docker image:

   docker build -t flask-k8s-hello-world .

   This command builds a Docker image from your Dockerfile. The -t flag tags the image with the name flask-k8s-hello-world. The . at the end specifies that the Dockerfile is in the current directory.

3. Tag the Docker image:

   docker tag flask-k8s-hello-world your-docker-username/flask-k8s-hello-world

   This step tags your image with your Docker Hub username, preparing it for pushing to Docker Hub. Replace your-docker-username with your actual Docker Hub username.

4. Push the image to Docker Hub:

   docker push your-docker-username/flask-k8s-hello-world

   This command uploads your Docker image to Docker Hub, making it accessible for your Kubernetes cluster to pull. Ensure you're logged in to Docker Hub (docker login) before running this command.

5. Deploy to Kubernetes:

   kubectl apply -f kubernetes-deployment.yaml

   This command creates or updates the resources defined in your kubernetes-deployment.yaml file in your Kubernetes cluster.

   Note: If already deployed, you can delete the existing deployment and redeploy: Check the status of the pods:

    kubectl get pods

   This shows the current running pods in your cluster. Delete the deployment:

   kubectl delete -f kubernetes-deployment.yaml

   This removes the existing deployment and associated resources.

   Redeploy the application:

   kubectl apply -f kubernetes-deployment.yaml

   This creates a fresh deployment with your updated configuration or image.

6. Access the application:

   kubectl port-forward service/flask-hello-world 8080:80

   This command forwards traffic from your local machine's port 8080 to port 80 of the flask-hello-world service in your Kubernetes cluster.

   Open a web browser and navigate to http://localhost:8080 You should now see your Flask application's "Hello, World!" message in your web browser.

The app.py file contains a simple Flask application that returns an HTML header with "Hello, World!".

The Dockerfile defines how to build the Docker image for our Flask application.

The kubernetes-deployment.yaml file defines both the Deployment and Service for our application.

1. Ensure your Kubernetes cluster is running and kubectl is configured correctly.

2. Apply the Kubernetes configuration:

   kubectl apply -f kubernetes-deployment.yaml

3. Check the status of your pods:

   kubectl get pods

4. Check the status of your service:

   kubectl get services flask-hello-world

Use port forwarding to access the application:

kubectl port-forward service/flask-hello-world 8080:80

Then open a web browser and go to http://localhost:8080

To remove the deployment and service:

kubectl delete -f kubernetes-deployment.yaml

If you encounter issues:

1. Check pod status:

   kubectl get pods

2. View pod logs:

   kubectl logs <pod-name>

3. Describe the service:

   kubectl describe service flask-hello-world