Transitioning from monolith to microservices requires careful planning.
When to Migrate#
Consider microservices when:
✓ Team scaling challenges
✓ Independent deployment needed
✓ Different scaling requirements per component
✓ Technology diversity requirements
Keep the monolith when:
✗ Small team (< 10 developers)
✗ Simple domain
✗ Unclear boundaries
✗ Premature optimization
Strangler Fig Pattern#
Phase 1: Identify boundaries
┌─────────────────────────────┐
│ Monolith │
│ ┌─────┐ ┌─────┐ ┌─────┐ │
│ │Users│ │Orders│ │Inv. │ │
│ └─────┘ └─────┘ └─────┘ │
└─────────────────────────────┘
Phase 2: Extract service
┌─────────────────────────────┐
│ Monolith │
│ ┌─────┐ ┌─────┐ │
│ │Users│ │Orders│ │
│ └─────┘ └─────┘ │
└─────────────────────────────┘
│
▼
┌─────────┐
│Inventory│ (New Service)
│ Service │
└─────────┘
Phase 3: Route traffic
┌──────────────┐
│ API Gateway │
└──────┬───────┘
│
┌────┴────┐
▼ ▼
┌────┐ ┌─────────┐
│Mono│ │Inventory│
│lith│ │ Service │
└────┘ └─────────┘
Identifying Service Boundaries#
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Database Decomposition#
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API Gateway for Migration#
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Event-Driven Communication#
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Data Migration Strategy#
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Service Communication#
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Common Pitfalls#
❌ Big bang migration
✓ Incremental extraction
❌ Distributed monolith (tight coupling)
✓ Loose coupling via events/APIs
❌ Shared database
✓ Database per service
❌ Synchronous chains
✓ Async communication where possible
❌ No observability
✓ Distributed tracing, logging, metrics
Start small, migrate incrementally, and maintain backward compatibility.