Auth API — FastAPI + JWT + Google OAuth2 + DynamoDB + AWS Lambda

REST API with JWT authentication, Google OAuth2 login, role-based access control, and DynamoDB persistence. Built to run locally with Docker and deployable to AWS Lambda with zero code changes.

Stack

Layer	Technology
Backend	Python 3.11 + FastAPI
Auth	JWT (python-jose) + Google OAuth2
Database	AWS DynamoDB (mocked locally with amazon/dynamodb-local)
Cloud	AWS Lambda + API Gateway (via Mangum adapter)
Container	Docker + Docker Compose
CI/CD	GitHub Actions

Architecture

Client → API Gateway → Lambda (Mangum) → FastAPI
                                         ├── /auth/register    (JWT)
                                         ├── /auth/login       (JWT)
                                         ├── /auth/google      (OAuth2)
                                         ├── /users/me         (protected)
                                         └── /users/           (admin only)
                                                    ↓
                                               DynamoDB

Endpoints

Method	Path	Auth	Description
GET	/	❌	Health check
POST	/auth/register	❌	Register with email + password
POST	/auth/login	❌	Login, returns JWT
GET	/auth/google	❌	Redirect to Google login
GET	/auth/google/callback	❌	Google OAuth2 callback
GET	/users/me	✅ JWT	Get current user profile
GET	/users/	✅ Admin	List all users

Run locally

# 1. Clone and configure
cp .env.example .env

# 2. Start API + DynamoDB local
docker compose -f docker/docker-compose.yml up

# 3. Open docs
open http://localhost:8000/docs

Google OAuth2 setup

1. Go to Google Cloud Console
2. Create a project → APIs & Services → Credentials → OAuth 2.0 Client ID
3. Add http://localhost:8000/auth/google/callback as authorized redirect URI
4. Copy Client ID and Secret to your .env

AWS Deployment

# Package for Lambda
pip install -r requirements.txt -t package/
cd package && zip -r ../function.zip . && cd ..
zip function.zip -r src/

# Deploy via AWS CLI
aws lambda create-function \
  --function-name auth-api \
  --runtime python3.11 \
  --handler src.main.handler \
  --zip-file fileb://function.zip \
  --environment Variables="{JWT_SECRET_KEY=...,USERS_TABLE=users}"

Run tests

pip install -r requirements.txt
pytest tests/ -v --cov=src