Monolith to microservices migration represents the strategic decomposition of tightly-coupled applications into independently deployable services. This architectural transformation became standard practice among high-scale companies between 2010-2015, driven by the need for team autonomy, deployment independence, and bounded scaling. The migration itself is a multi-phase journey requiring careful planning around domain boundaries, data ownership, deployment strategies, and organizational alignment—not a one-time rewrite. The strangler fig pattern emerges as the industry-proven approach because it allows incremental risk mitigation while maintaining production stability, contrasting sharply with big-bang rewrites that typically fail at scale.
What This Cheat Sheet Covers
This topic spans 20 focused tables and 113 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.
Table 1: Migration Strategy Patterns
| Pattern | Example | Description |
|---|---|---|
Route /orders/* → new serviceRoute /users/* → monolith | • Incrementally replace monolith functionality by routing traffic to new services while old code remains • most widely adopted migration approach for production systems | |
interface PaymentGatewayclass LegacyPayment implements PaymentGatewayclass NewPayment implements PaymentGateway | Create abstraction layer in monolith code that allows switching between old and new implementations via configuration without branching source code | |
Send requests to both old & new Compare responses Route production to validated system | • Run new microservice alongside monolith with same requests • compare outputs to verify correctness before cutover |