Payment Microservice - Hexagonal Architecture Implementation

Background

The goal of this project was to build a maintainable and scalable payment microservice following hexagonal architecture principles. The focus was on creating a system where business logic is completely isolated from external concerns, making it easily testable and adaptable to different infrastructure requirements.

Strategy & Solution

• Implement hexagonal architecture with clear ports (interfaces) and adapters (implementations) separation.
• Design domain models that are framework-agnostic and contain pure business logic.
• Create repository interfaces that can be implemented by different storage adapters (PostgreSQL, in-memory, etc.).
• Use dependency injection to maintain loose coupling between layers and enable easy testing and configuration changes.

Responsibilities & Scope

• Architected the payment service using hexagonal architecture with domain models, repository ports, and database adapters.
• Implemented the DatabaseAdapter as a secondary adapter that translates domain operations to PostgreSQL operations.
• Designed comprehensive payment record management with support for multiple payment methods and status tracking.
• Created robust error handling and transaction management using SQLAlchemy ORM with proper connection pooling.
• Configured Docker secrets integration for secure database credential management in containerized environments.

Results & Impact

• Successfully implemented hexagonal architecture that completely isolates business logic from infrastructure concerns.
• Created a flexible payment system supporting multiple payment methods (Credit Card, Bank Transfer, E-Wallet, QRIS) through domain models.
• Achieved database connection reliability through proper connection pooling and health check mechanisms.
• Implemented comprehensive metadata handling for payment gateway integrations with JSON serialization support.
• Designed scalable database schema with optimized indexing for payment lookups and order associations.