devops-k8s-3tier-app

A production-grade, multi-container 3-tier microservices application stack containerized with Docker, automated via GitHub Actions CI/CD, and orchestrated on Kubernetes using Minikube.

---

📸 Architecture & Live Demonstration

System Architecture Diagram

Key Deployment & Pipeline Highlights

Kubernetes Deployment Status	GitHub Actions CI/CD Success

End-to-End API Verification	K8s Data Persistence Proof

---

🎯 Overview & Motivation

Modern cloud applications require robust microservice separation, automated continuous integration, resilient container orchestration, and self-healing storage solutions.

devops-k8s-3tier-app demonstrates end-to-end DevOps practices by implementing a 3-tier architecture:

• Presentation Layer: Nginx reverse proxy handling HTTP traffic routing and security header enforcement.
• Application Layer: Flask REST API running under a multi-worker Gunicorn WSGI server with MySQL connection pooling.
• Data Layer: MySQL 8.0 relational database with persistent storage volume claims.

This repository serves as a flagship portfolio piece showcasing real-world cloud engineering, Docker containerization, Kubernetes manifest design, and automated pipeline execution.

---

✨ Features

• 🚀 RESTful Microservices Backend: Clean REST API offering /health status monitoring and complete item CRUD endpoints.
• ⚡ Production-Ready WSGI & Connection Pooling: Powered by Gunicorn WSGI server and thread-safe MySQL connection pooling to prevent connection starvation.
• 🛡️ Container Security & Isolation: Non-root container execution (appuser UID 10001), security response headers in Nginx (X-Frame-Options, X-Content-Type-Options), and Kubernetes network isolation.
• 📦 Docker Compose Local Development: One-command multi-container local startup with healthchecks and automatic container dependencies.
• ☸️ Kubernetes Minikube Deployment: Declarative K8s manifests specifying Namespace, ConfigMaps, Secrets, PV/PVC storage, health probes (readiness & liveness), resource limits, and service exposing (NodePort & ClusterIP).
• 🔄 Automated CI/CD Pipeline: GitHub Actions workflow executing Pytest automated testing prior to building and pushing Docker images to DockerHub.

---

📚 Technical Documentation Directory

Document	Description
📖 Architecture Specification	In-depth technical breakdown of network topology, tiers, security context, and K8s resources.
📜 Architectural Decision Records (ADRs)	Records of core technical decisions (Nginx proxy, Gunicorn WSGI, MySQL pool, NodePort).
🔌 REST API Reference	Full endpoint documentation, request/response schemas, error codes, and cURL examples.
🛠️ Setup & Installation Guide	Detailed installation steps for Docker Compose local dev and Minikube K8s setup.
⚙️ Usage & Operations Guide	Operational workflows, cluster scaling commands, logging streams, and troubleshooting.
💻 Development & Testing Guide	Guidelines for local Python virtualenvs, running Pytest suites, and container builds.

---

🛠️ Tech Stack

• Backend: Python 3.11, Flask 3.0, Gunicorn 21.2
• Database: MySQL 8.0, mysql-connector-python 8.2
• Reverse Proxy: Nginx (Alpine)
• Containerization: Docker, Docker Compose
• Orchestration: Kubernetes (Minikube), kubectl
• Automation & Testing: Bash, Pytest, GitHub Actions

---

⚡ Installation & Quickstart

Prerequisites

• Docker Engine & Docker Compose
• Minikube & kubectl
• Git

1. Local Development (Docker Compose)

git clone https://github.com/sedmugen/devops-k8s-3tier-app.git
cd devops-k8s-3tier-app
cp .env.example .env
docker compose -f app/docker-compose.yml up -d --build

Access the application at http://localhost/health.

2. Kubernetes Cluster Deployment (Minikube)

chmod +x start.sh
./start.sh

See docs/setup.md for detailed cluster setup and manifest validation procedures.

---

📖 API Documentation Overview

For full request/response payloads, see docs/api.md.

# Check health
curl -i http://localhost/health

# Create item
curl -i -X POST http://localhost/api/items \
  -H "Content-Type: application/json" \
  -d '{"name": "DevOps Portfolio", "description": "3-Tier Stack on K8s"}'

# List items
curl -i http://localhost/api/items

# Delete item
curl -i -X DELETE http://localhost/api/items/1

---

🗺️ Roadmap & Testing

• Gunicorn WSGI multi-worker integration
• Thread-safe MySQL connection pooling
• Non-root container security context (appuser UID 10001)
• Pytest automated test suite & CI/CD pipeline integration
• Ingress Controller with TLS cert-manager integration
• Prometheus & Grafana monitoring dashboards

---

📄 License & Credits

This project is licensed under the MIT License - see the LICENSE file for details.

Developed & Maintained by sedmugen.