Mini Flask App Deployment on Kubernetes

A step-by-step guide for running a Flask web application containerized with Docker and deployed on Kubernetes.

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Table of Contents

1. Project Overview
2. Prerequisites
3. Project Structure
4. Setup and Run Locally
5. Dockerization
6. Kubernetes Deployment
7. Accessing the App
8. Next Steps / Enhancements
9. License

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Project Overview

This project demonstrates how to:

• Develop a simple Flask web app
• Containerize it using Docker
• Deploy it to a Kubernetes cluster (Minikube / EKS / GKE)
• Make it production-ready with Gunicorn

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Prerequisites

Make sure you have the following installed:

• Python 3.12
• Docker
• Kubernetes CLI (kubectl)
• Minikube (for local cluster testing)

Optional:

• Helm for advanced deployment
• GitHub / Docker Hub account for pushing images

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Project Structure

mini-flask-app/
├── application.py      # Flask app
├── templates/
│   └── index.html      # HTML page rendered by Flask
├── requirements.txt    # Python dependencies
├── Dockerfile          # Container definition
└── README.md

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Setup and Run Locally

1. Create a virtual environment (optional):

python -m venv venv
source venv/bin/activate  # Linux/Mac
venv\Scripts\activate     # Windows

2. Install dependencies:

pip install -r requirements.txt

3. Run the Flask app:

python application.py

Visit: http://127.0.0.1:5000

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Dockerization

1. Build Docker image:

docker build -t mini_app:v1.0 .

2. Test locally:

docker run -p 5000:5000 mini_app:v1.0

3. Push to Docker Hub:

docker tag mini_app:v1.0 <dockerhub-username>/mini_app:v1.0
docker push <dockerhub-username>/mini_app:v1.0

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Kubernetes Deployment

1. Start Minikube:

minikube start

2. Create a deployment:

kubectl create deployment miniapp --image=<dockerhub-username>/mini_app:v1.0

3. Expose the deployment:

kubectl expose deployment miniapp --type=NodePort --port=5000

4. Check pods:

kubectl get pods

5. Get service info:

kubectl get svc miniapp

6. Access the app:

• For Minikube:

minikube service miniapp

• Or open in browser:

http://<minikube-ip>:<nodeport>

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Accessing the App

• Pod IPs are internal and not accessible from outside the cluster.
• Use NodePort or Ingress to access externally.
• Example NodePort URL: http://192.168.49.2:32698

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Next Steps / Enhancements

• Add liveness and readiness probes for health checks
• Implement Ingress + TLS for domain access
• Automate deployment using CI/CD pipelines (GitHub Actions / ArgoCD)
• Scale horizontally using replicas

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License

This project is open-source and free to use under the MIT License.

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