Domain-Driven Design

Answer-first: Migrating an e-commerce monolith to 21+ distributed microservices using Golang & DDD. Explore Kratos architecture, Saga patterns, and race conditions. Scaling an e-commerce platform past 10,000+ orders per day containing multiple SKUs across dynamic warehouses is where naive architecture breaks down. Hardware scaling ceases to be a magic bullet when distributed transactions, race conditions, and eventual consistency are involved. In this deep tech dive, we will tear apart the “Hello World” abstraction of Microservices. We will look at exactly how our 21-service distributed ecosystem interacts under the hood. I will share the exact Golang architectural patterns (Kratos), the Saga orchestration for distributed checkout, and how we handle race conditions under severe load. ...

Answer-first: A detailed technical breakdown of how a monolithic e-commerce application is segregated into 6 logical Business Domains with 21 isolated microservices. “Why 21 services? Isn’t that overkill?” This is the most common question I get when discussing the Golang microservice architecture we built to handle massive scale. The short answer is: No, because Conway’s Law is real. When you have multiple squads touching the same codebase, feature overlap creates friction. By rigidly enforcing Domain-Driven Design (DDD), we sliced our e-commerce monolith into 6 highly cohesive, loosely coupled Business Domains. Each domain is completely self-sufficient and owns its own Postgres databases. ...

Part 3: Domain-Driven Design (DDD) Boundaries in a Modular Monolith The biggest reason engineering teams fear the Monolith architecture is due to terrible past experiences with “Spaghetti Monoliths” or the “Big Ball of Mud” — where the code for the Billing function calls directly into the database of the Cart function, creating an inextricable web of cross-dependencies. To leverage the performance advantages of a Monolith while still achieving independent development velocity like Microservices, we must build a Modular Monolith. The key to this architecture is strictly applying Domain-Driven Design (DDD) principles and establishing hard “borders” right within the code. ...