Monolith to Microservices: A Practical Migration Guide

When to Consider Microservices

Microservices aren't always the answer. Consider migrating when: deployment cycles are slow, teams are stepping on each other's toes, or scaling specific features requires scaling everything.

The Strangler Fig Pattern

This pattern lets you gradually replace parts of a monolith without a big-bang rewrite.

Phase 1: Assessment

Domain analysis, dependency mapping, and data flow analysis. Identify the most independent modules that can be extracted first.

Phase 2: Foundation

Set up the infrastructure: API Gateway, Service Mesh, Observability stack, and CI/CD pipelines for independent deployments.

Phase 3: First Service Extraction

Start with the most independent module. Often authentication, notifications, or file processing.

Phase 4: Event-Driven Communication

Replace synchronous calls between services with event-driven messaging for better resilience.

const order = await orderService.createOrder(data);
await eventBus.emit("order.created", { orderId: order.id, items: order.items });

Tools We Use

Mistakes to Avoid

1. Don't create too many services too fast: start with 2-3
2. Don't share databases between services
3. Don't ignore observability. You need distributed tracing from day one