When should I migrate to microservices?

When your monolith causes deployment bottlenecks, team scaling issues, or inability to adopt different tech stacks for different domains. Do not migrate for the sake of architecture trends.

How many services should I start with?

Extract 2-3 services initially. Learn the operational overhead before decomposing further. Many teams over-decompose too early.

Should I use Kubernetes?

Not necessarily. Kubernetes adds significant operational complexity. ECS, Cloud Run, or even Docker Compose may be sufficient for smaller service counts.

Microservices Migration Checklist

Migrate from monolith to microservices with a structured approach to service boundaries, data ownership, and distributed system observability.

Checklist: Microservices Migration (engineering)

Migrating from a monolith to microservices is one of the highest-risk architectural changes a team can undertake. Done poorly, it creates a distributed monolith that is harder to operate. This checklist covers the strategic and tactical steps for a successful migration.

Checklist Items

Identify service boundaries using domain modeling [critical]: Use domain-driven design to identify bounded contexts that become natural service boundaries.
Decompose the database per service [critical]: Each service should own its data. Plan data migration and eventual consistency patterns.
Set up inter-service communication [critical]: Choose synchronous (REST/gRPC) or asynchronous (message queues) patterns based on coupling requirements.
Implement distributed tracing [important]: Add trace IDs across service calls to debug request flows spanning multiple services.
Design failure handling and circuit breakers [important]: Implement circuit breakers, retries with backoff, and fallback responses for service-to-service calls.
Set up service discovery [important]: Configure DNS-based or registry-based service discovery so services can locate each other dynamically.
Plan the strangler fig migration pattern [important]: Extract services incrementally from the monolith rather than attempting a big-bang rewrite.
Configure centralized logging [recommended]: Aggregate logs from all services into a single platform with correlation IDs for cross-service debugging.
Implement API gateway [recommended]: Add an API gateway for routing, authentication, rate limiting, and request aggregation at the edge.
Define service SLOs and SLIs [recommended]: Set service-level objectives for latency, availability, and error rate for each service.

Common Mistakes

Big-bang migration: Use the strangler fig pattern. Extract one service at a time, validate, then move to the next.
Shared database between services: Each service must own its data. Shared databases couple services and negate the benefits of microservices.
No observability from the start: Distributed tracing, centralized logging, and service metrics are essential from the first extracted service.

Frequently Asked Questions

When should I migrate to microservices?: When your monolith causes deployment bottlenecks, team scaling issues, or inability to adopt different tech stacks for different domains. Do not migrate for the sake of architecture trends.
How many services should I start with?: Extract 2-3 services initially. Learn the operational overhead before decomposing further. Many teams over-decompose too early.
Should I use Kubernetes?: Not necessarily. Kubernetes adds significant operational complexity. ECS, Cloud Run, or even Docker Compose may be sufficient for smaller service counts.