🧮 FastAPI Calculator – Module 8 Assignment

A fully functional FastAPI-based Calculator Web Application built as part of Module 8 Assignment.
It integrates complete CI/CD automation, Docker containerization, automated testing, and security scanning — following real-world software engineering practices.

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⚙️ Features

✅ Perform all arithmetic operations: Addition, Subtraction, Multiplication, Division
✅ Responsive Web UI using Jinja2 Templates
✅ Singleton Logger implementation for centralized logging
✅ RESTful Endpoints for each operation
✅ Unit, Integration, and E2E tests with 100% coverage
✅ Automated GitHub Actions CI/CD pipeline
✅ Dockerized deployment with vulnerability scanning (Trivy)
✅ Follows clean code architecture and design patterns

📁 Project Structure

Module-8
├── app/
│   ├── __init__.py
│   ├── logger.py               # Singleton Logger class (creates logs/app.log)
│   └── operations/__init__.py  # Core arithmetic logic
│
├── templates/
│   └── index.html              # Web interface (Jinja2)
│
├── static/
│   └── favicon.ico             # Application icon
│
├── tests/
│   ├── unit/                   # Unit tests for core modules
│   ├── integration/            # API-level integration tests
│   ├── e2e/                    # Playwright-based UI tests
│   └── conftest.py
│
├── main.py                     # FastAPI app entry point
├── requirements.txt            # All dependencies
├── Dockerfile                  # Docker container configuration
├── .github/workflows/ci.yml    # GitHub Actions workflow
└── README.md

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🧩 Installation & Local Setup

1️⃣ Clone the repository

git clone https://github.com/Rajat-njit/Module-8.git
cd Module-8

2️⃣ Create and activate a virtual environment

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

3️⃣ Install dependencies

pip install -r requirements.txt
playwright install

4️⃣ Run the FastAPI app

uvicorn main:app --reload

Now visit 👉 http://127.0.0.1:8000

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📦 requirements.txt Contents

annotated-doc==0.0.3
annotated-types==0.7.0
anyio==4.11.0
certifi==2025.10.5
click==8.3.0
fastapi==0.120.1
h11==0.16.0
httpcore==1.0.9
httpx==0.28.1
idna==3.11
pydantic==2.12.3
pydantic_core==2.41.4
sniffio==1.3.1
starlette==0.48.0
typing-inspection==0.4.2
typing_extensions==4.15.0
uvicorn==0.38.0
playwright>=1.48.0
pytest>=8.3.3
pytest-cov>=6.0.0
pytest-playwright>=0.5.0
requests>=2.32.3
jinja2>=3.1.4

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🧪 Testing

🧩 Unit & Integration Tests

pytest --cov=app --cov-report=term-missing

🌐 End-to-End (E2E) Tests

pytest tests/e2e -v

📈 Expected output:

50 passed, 1 xfailed in 6.7s
Coverage: 100 %

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🐳 Docker Deployment

Build Docker image

docker build -t rajatpednekar/module-8 .

Run container

docker run -d -p 8000:8000 --name fastapi-calculator rajatpednekar/module-8

Open app at: http://localhost:8000

Check running containers:

docker ps

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🧠 Design Pattern Map

Pattern	Location	Purpose
Singleton	app/logger.py	Ensures a single shared logger instance
Factory	app/operations/__init__.py	Creates operation logic dynamically
Observer (Logger)	logger reacts to user events	Captures every API action
Facade	main.py	Provides unified interface to API and UI layers

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🔧 Enhancements Made

Area	Enhancement
🧩 Logging System	Added Singleton-based AppLogger with auto log folder creation
🌐 Frontend	Redesigned calculator layout with improved dark theme
🧪 Testing Suite	Added Unit + Integration + Playwright-based UI tests
🧱 Dockerization	Added Dockerfile for deployment portability
🔁 CI/CD Pipeline	Integrated GitHub Actions workflow with Trivy scanning
🛡️ Security Fixes	Upgraded h11 to 0.16.0 to patch CVE-2025-43859
⚡ Error Handling	Improved division by zero and invalid input messages
🧩 Favicon + Static Support	Added /static route and graceful 404 fallback

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⚙️ Continuous Integration (GitHub Actions)

The workflow automates every stage from testing to deployment.

Workflow file: .github/workflows/ci.yml

CI/CD Pipeline Steps:

1. 🧰 Setup Python + dependencies
2. ✅ Run Unit, Integration, and E2E tests
3. 🧾 Generate coverage report
4. 🔒 Run Trivy vulnerability scan
5. 🐳 Build and push Docker image → rajatpednekar/module-8:latest

All builds verified via the badge at the top of this README ✔️

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🧾 Logging

All runtime events are logged in:

logs/app.log

Sample log entries:

2025-10-25 14:33:11 [INFO] Application started.
2025-10-25 14:33:18 [INFO] POST /add | a=5, b=3 | result=8
2025-10-25 14:33:20 [ERROR] Division by zero attempted.

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🧩 Security Scanning

Integrated Trivy Security Action checks for vulnerabilities in:

• OS-level packages
• Python dependencies

✅ No vulnerabilities found after upgrading to h11==0.16.0.

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🏁 Final Results

Category	Result
✅ App Functionality	All operations working correctly
✅ Logging System	Fully functional & persistent
✅ Unit + Integration + E2E Tests	100% coverage
✅ GitHub Actions Workflow	All stages passed successfully
✅ Security Scan	0 Critical/High vulnerabilities
✅ Docker Image	Pushed to Docker Hub
🌐 Web App Live Demo	Accessible at localhost:8000

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👤 Author

Rajat Pednekar

📍 Master’s in Computer Science – New Jersey Institute of Technology

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