MONOLITH VS MICROSERVICES DECISION FRAMEWORK

CURRENT STATE ASSESSMENT:
• Team size: 12 engineers
• Deployment frequency: 3-4 times per week
• Monolith age: 18 months
• Pain signals: Database lock contention on user-auth writes, occasional 500ms API latency spikes

MICROSERVICES READINESS SCORE: 4/10
✗ Team too small to support observability and debugging across services
✗ Deployment pipeline not mature enough (CI/CD is automated but no canary deploys)
✓ Clear service boundaries exist (auth, billing, content)
✗ No distributed tracing or circuit breakers in place

RECOMMENDATION: STAY MONOLITHIC FOR NOW

REASON:
Microservices would introduce:
• 2-3 more DevOps hires needed (20-30% org expansion)
• 40+ hours per engineer learning distributed systems patterns
• 6-12 month migration risk with zero product velocity

INSTEAD - MODULARIZE THE MONOLITH:
• Split auth logic into a separate internal package (dependency injection)
• Extract billing into a separate database schema with read replicas
• Set up a separate cache layer for auth (Redis) to relieve DB contention
• Add database indexing on hot queries (auth writes)

COST: 2-3 weeks of refactoring. Payoff: Eliminate the latency spike, gain 6 months of runway.

REVISIT THIS DECISION AT:
• 30 engineers, OR
• Deployment frequency needs to exceed once per day per team, OR
• Database locks return despite indexing

That's when microservices ROI turns positive.