.NET Architecture & System Design Interview Question #123

What is the Strangler Fig pattern for system migration?

Microservices, API Gateway, Service Communication & Event-Driven Architecture Mid-Level Intermediate

Quick Interview Answer

The Strangler Fig pattern incrementally replaces a legacy system by routing selected capabilities to a new implementation while the remaining functionality continues to use the old system.

Detailed Explanation

The Strangler Fig pattern incrementally replaces a legacy system by routing selected capabilities to a new implementation while the remaining functionality continues to use the old system.

This reduces the risk of a big-bang rewrite. Teams can migrate one bounded capability at a time, verify it in production, and gradually retire the legacy implementation.

Code Example

Clients
   |
Routing Layer
  /        Legacy     New System

Move routes gradually
until Legacy can be retired.