A lightweight, modular FastAPI application for order management.

Built as a modular monolith, the project organizes code by domain (e.g., orders, users) rather than by technical layers alone. It uses PostgreSQL for data storage, Alembic for schema migrations, and SQLite for fast, isolated unit tests. The application is containerized with Docker for consistent local development and deployment.

This structure keeps concerns well-defined in a monolithic codebase while encouraging boundaries that translate well to microservices, without introducing that complexity prematurely.

The codebase follows a domain-oriented structure combined with the Service Layer and Repository patterns. Each module (e.g., orders, users) is self-contained and implements a consistent internal layout:

Key characteristics:

• Thin controllers: Routes delegate all non-trivial logic to services
• Explicit business layer: Services centralize rules and workflows
• Decoupled data access: Repositories isolate database interactions
• Domain isolation: Each module is self-contained, reducing cross-coupling
• Testability: Business logic can be tested independently of HTTP and database layers

The design prioritizes clarity, testability, and maintainability, while remaining flexible enough to evolve into a distributed architecture if needed.

• Docker

This will spin up two containers:

• PostgreSQL
• Application in development mode with auto-reload and debug

API will be available at:

Swagger UI at: