AWS re:Invent 2025 - Circuit Breaker, Saga & Strangler Fig: Patterns for Transformation (MAM358)

AWS re:Invent 2025 - Circuit Breaker, Saga & Strangler Fig: Patterns for Transformation (MAM358)

Introduction

• This presentation explores three key architectural patterns - Circuit Breaker, Saga, and Strangler Fig - and how they can be leveraged to enable successful application transformation and modernization.
• These patterns address common challenges faced during complex migration and modernization initiatives, providing strategies to mitigate risks, manage dependencies, and incrementally migrate legacy systems.

Circuit Breaker Pattern

• Overview: The Circuit Breaker pattern is a defensive mechanism that prevents cascading failures in distributed systems by quickly detecting and isolating failures.
• Key Principles:
  • Monitoring for failures and tripping the "circuit breaker" when a certain failure threshold is reached
  • Providing a fallback or alternative response when the circuit breaker is tripped
  • Automatically resetting the circuit breaker after a cooldown period to re-attempt the original operation
• Benefits:
  • Protects downstream services from being overwhelmed by failures in dependent services
  • Enables graceful degradation of functionality during failures
  • Facilitates progressive rollout of new features or services
• Example Use Case: Migrating a monolithic e-commerce application to a microservices architecture. The Circuit Breaker pattern can be used to isolate failures in individual services, preventing the entire system from going down.

Saga Pattern

• Overview: The Saga pattern is a way to manage distributed transactions and maintain data consistency across multiple services.
• Key Principles:
  • Breaking down a complex transaction into a sequence of smaller, independent transactions
  • Defining compensating actions to undo the effects of each transaction in the event of a failure
  • Coordinating the execution of the transaction steps and compensating actions
• Benefits:
  • Ensures data consistency and integrity across multiple services
  • Provides a structured approach to handling failures in distributed transactions
  • Enables incremental migration of legacy systems by allowing partial transactions to be executed
• Example Use Case: Migrating a legacy order management system to a new microservices-based architecture. The Saga pattern can be used to manage the complex order fulfillment process, ensuring data consistency across services.

Strangler Fig Pattern

• Overview: The Strangler Fig pattern is a gradual, incremental approach to replacing a legacy application by encapsulating and "strangling" the old system, while simultaneously building a new system.
• Key Principles:
  • Identifying and isolating the core functionality of the legacy system
  • Incrementally replacing the legacy system's functionality with new services or components
  • Gradually "strangling" the legacy system by routing traffic through the new components
• Benefits:
  • Reduces the risk and complexity of a big-bang migration
  • Allows for a phased, iterative approach to modernization
  • Enables the new system to be built and tested alongside the legacy system
• Example Use Case: Modernizing a legacy airline reservation system. The Strangler Fig pattern can be used to incrementally replace the legacy system's functionality, such as flight booking, seat selection, and payment processing, with new microservices.

Key Takeaways

• The Circuit Breaker, Saga, and Strangler Fig patterns provide proven strategies for managing the complexity and risks associated with application transformation and modernization initiatives.
• These patterns enable organizations to incrementally migrate legacy systems, manage distributed transactions, and protect against cascading failures - all of which are critical for successful digital transformation.
• By leveraging these patterns, organizations can reduce the risks and costs of modernization, while delivering new capabilities and improving the overall resilience and scalability of their application landscape.