Microservices / Saga Pattern Interview Questions 2026

Your microservices use synchronous REST calls and you're experiencing cascading failures. You implement circuit breakers, but during the open state, users get blank pages. How do you improve user experience during failures?

Design a system where microservice A must call microservices B, C, and D. If any one fails, the entire operation must rollback. B and C have already succeeded when D fails. How do you handle this?

One microservice in your call chain has started responding slowly (not failing, just slow). Explain how a circuit breaker and a timeout differ in protecting the rest of the system, and why you often need both.

Your company wants to migrate from a monolith to microservices in 6 months. You're asked to lead this. What's the first thing you tell management?

Two microservices in your architecture (Trip Service and Payment Service) need to communicate when a trip ends. Would you use synchronous REST calls or an async event, and why?

How do you handle database migrations when you have 10 instances of a service running and you need to add a NOT NULL column?

Your microservices use HTTP REST. Under peak load, Service A waits synchronously for Service B which waits for Service C. Adding a new feature requires adding Service D to the chain. What's the systemic problem?

Explain the difference between choreography and orchestration in saga pattern. When would you choose each?

Design the API contract between microservices. When service A calls service B, how do you version the contract so service B can change without breaking service A?

Your 15 microservices all have their own logging format. Log aggregation is unusable because fields differ. How do you standardize this across teams without rewriting all services?

Explain the Outbox Pattern. When is it necessary and how does it solve the dual-write problem?