🚀 Microservices Decomposition Crib Sheet

Table of Contents

Link	Section
Phase 1: Assessment & Domain Discovery	Assessment
Phase 2: Strategic Planning	Planning
Phase 3: Iterative Decomposition (Strangler Pattern)	Decomposition
Phase 4: Data Decoupling	Data
Phase 5: Continuous Integration/Continuous Delivery (CI/CD)	CI/CD
Phase 6: Team Autonomy and Organization Alignment	Team
Phase 7: Security and Compliance	Security
Phase 8: Iterative Improvement (Continuous Evolution)	Evolution
Strangler Fig Pattern (Strangler Pattern)	Pattern
Other Common Patterns & Techniques	Patterns

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Phase 1: Assessment & Domain Discovery

• ✅ Domain-Driven Design (DDD):

  • Identify bounded contexts and domain boundaries.
  • Perform Event Storming to visualize domain logic.

• Buzzwords: Domain-driven design, event storming, bounded context, ubiquitous language.

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Phase 2: Strategic Planning

• Identify Core Domains and Support Domains.

• Create a roadmap with iterative milestones for extraction.

• Define microservices around business capabilities.

• Buzzwords: Strategic domain modeling, domain decomposition, service boundaries, domain decomposition.

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Phase 3: Iterative Decomposition (Strangler Pattern)

• Wrap existing monolith functionalities behind clear API contracts.

• Gradually extract functionality into separate microservices, starting from simplest or least coupled.

• Continuously integrate extracted services using API gateways, Service Mesh, and Message Brokers.

• Buzzwords: Service extraction, incremental refactoring, API gateway, service mesh, message broker, sidecar patterns.

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Phase 4: Data Decoupling

• Gradually separate data storage, ensuring microservices own their databases (Database-per-service).

• Ensure eventual consistency through Event-driven Architecture and Saga patterns.

• Use Change Data Capture (CDC) to synchronize data where needed.

• Buzzwords: Data ownership, event-driven architecture, eventual consistency, CQRS, Saga pattern, polyglot persistence.

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Phase 5: Continuous Integration/Continuous Delivery (CI/CD)

• Automate deployment pipelines for each service independently.

• Utilize containerization (Docker/Kubernetes) to ensure consistent environments.

• Implement observability, logging, and monitoring tools (Prometheus, Grafana, OpenTelemetry).

• Buzzwords: CI/CD pipelines, container orchestration, observability, Kubernetes, GitOps, telemetry.

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Phase 6: Team Autonomy and Organization Alignment

• Adopt DevOps culture and cross-functional, autonomous teams owning individual services.

• Clearly define service boundaries to improve ownership and accountability.

• Buzzwords: DevOps culture, cross-functional teams, team autonomy, service ownership.

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Phase 7: Security and Compliance

• Enforce security policies via Zero Trust architecture and fine-grained access control.

• Shift-left security with DevSecOps approaches.

• Ensure compliance through automation and regular auditing.

• Buzzwords: Zero trust, DevSecOps, IAM, RBAC, shift-left security, compliance as code.

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Phase 8: Iterative Improvement (Continuous Evolution)

• Regularly evaluate microservices boundaries, scale, and performance.

• Gradually optimize, merge, or further split services based on feedback loops.

• Implement chaos engineering practices to ensure resilience and reliability.

• Buzzwords: Feedback loops, continuous improvement, chaos engineering, resilience testing, iterative optimization.

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Strangler Fig Pattern (Strangler Pattern)

• Concept: Gradually replace parts of your monolith by redirecting functionalities incrementally to microservices until the monolith is eventually retired.
• Benefit: Low-risk incremental refactoring with minimal disruption.

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Other Common Patterns And Techniques:

1. Event Storming

   • Collaborative discovery of domain logic.
   • Helps visualize domain boundaries and identify microservices.

2. Domain-Driven Design (DDD)

   • Uses Bounded Contexts and Ubiquitous Language to define service boundaries.

3. Event-Driven Architecture (EDA)

   • Break monolith based on domain events.
   • Utilize event sourcing and CQRS for decoupled communication.

4. Anti-Corruption Layer

   • Introduce a layer of abstraction to isolate new microservices from legacy code complexities.

5. Branch by Abstraction

   • Incrementally refactor functionality into services behind an abstraction layer, safely managing technical debt and legacy integration.

6. API Gateway and Backend-for-Frontend (BFF)

   • Centralized gateways to orchestrate and route requests.

7. Database Per Service / Polyglot Persistence

   • Isolate data storage for each service to eliminate coupling.

8. Service Mesh

   • Decouples communication, discovery, security, and traffic management using sidecars (e.g., Istio, Linkerd).

9. Sidecar Pattern

   • Provides standardized functionalities (monitoring, logging, tracing) attached to each microservice.

10. Branch by Abstraction

    • Gradually introduce microservices behind feature toggles or switches to maintain a running, stable system throughout the refactoring.

11. API Gateway

    • Single entry-point for all microservices, handling concerns such as load balancing, authentication, logging, and rate limiting.

12. SAGA Pattern

    • Manages distributed transactions across multiple services using event-driven coordination.

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Buzzwords Recap:

• Strangler Pattern (Strangler Fig)
• Domain-driven Design
• Event Storming
• Bounded Context
• Event-Driven Architecture
• Anti-Corruption Layer
• CQRS & Event Sourcing
• API Gateway
• Backend-for-Frontend (BFF)
• Service Mesh
• Polyglot Persistence
• Database Per Service
• Sidecar
• Branch-by-Abstraction
• Saga Pattern

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