Architecting a Go Backend with Event-Driven Design and the Outbox Pattern

The Transactional Outbox Pattern solves the dual-write problem in event-driven systems by storing both business data and events in a single database transaction. When creating an order, both the order record and an outbox event are written atomically to PostgreSQL. A separate background consumer then polls the outbox table, publishes unpublished events to Kafka (Redpanda), and marks them as sent. This guarantees at-least-once delivery without risking data inconsistency. The implementation uses Clean Architecture principles with separated domain, use case, and infrastructure layers, includes Docker Compose setup with Postgres and Redpanda, and features hot-reload development with Air. The pattern decouples event publishing from business logic while ensuring reliability through database transactions and retry mechanisms.