Isn't the Monolith Just Enough?
- 1. Isn’t the Monolith Just Enough? Petru Flueras Software Architect - Visma Software @pflueras Codecamp, April 2022
- 2. Thank you!
- 3. Journey: follow the lifecycle of a project starting from the startup/inception phase all the way to a matured product Would you go microservices architecture from the very beginning?
- 4. Monolith First Most successful microservice stories have started with a monolith Products started as a microservice system from scratch, ended up in a serious trouble It may be hard to scale a poorly designed but successful software system, but that's still a better place to be than its inverse source: https://martinfowler.com/bliki/MonolithFirst.html
- 5. Monolith First #2 You shouldn't start a new project with microservices, even if you're sure your application will be big enough to make it worthwhile source: https://martinfowler.com/bliki/MonolithFirst.html
- 6. Design of the monolith Modularization: strong encapsulation, well-defined interfaces, explicit dependencies between modules (stable boundaries between modules) Simon Brown: if you can’t build a well-structured monolith, what makes you think microservices is the answer?
- 7. Modularization done right As project grows, don’t use layers (e.g. presentation-domain-data) as the top level modules, instead make you top level (domain oriented) modules be full-stack which are internally layered https://martinfowler.com/bliki/PresentationDomainDataLayering.html
- 8. Make each program to do one thing well. To do a new job, build afresh rather than complicate old programs by adding new “features” UNIX Time-Sharing System: Forward (Douglas McIlroy - 1978) Bounded Context (Domain Driven Design): a way to mark boundaries and relationships between different domain models It is almost always incorrect to begin the decomposition of a system into modules on the basis of a flowchart. Instead, each module is designed to hide difficult design decisions. On the Criteria To Be Used in Decomposing Systems into Modules (1972) How to get the right shaped modules?
- 9. Before migrating to Microservices: More Complexity? Image: https://www.n-ix.com/microservices-vs-monolith-which-architecture-best-choice-your-business/
- 10. Complexity #1: Data Consistency Database transactions (ACID), Referential integrity Monolith Eventual consistency (BASE), Distributed transactions - 2PC, SAGA Pattern Microservices
- 11. Complexity #2: Network fallacies 1. The network is reliable. 2. Latency is zero. 3. Bandwidth is infinite. 4. The network is secure. 5. Topology doesn't change. 6. There is one administrator. 7. Transport cost is zero. 8. The network is homogeneous.
- 12. Complexity #3: CI & CD Monolith Microservices
- 13. Complexity #4: Monitoring Monolith Microservices
- 14. Complexity #5: Integration Testing
- 15. Complexity #6: Security ● Authentication: some sort of single sign-on (SSO) ○ End users ■ Single sign-on gateway & identity provider ■ OpenID Connect ○ Service-to-service ■ Basic Auth, OpenID Connect, Client certificates, API keys ■ Service accounts ● Attack surface area is increased ● Don’t repeat yourself
- 17. The Seven (More) Deadly Sins of Microservices (Daniel Bryant) Microservices Highway to hell (Broutin Mathieu) Avoiding Microservice Megadisasters (Jimmy Bogard)
- 18. Conscious decision! (Customers don’t care about your tech stack)
- 19. ● Scalability: independently scalable microservices ○ Time and cost efficient (auto)scaling ○ Fast startup time & low memory footprint ○ CPU / memory intensive applications ● Autonomous teams ● Deliver faster business value (slow CI/CD pipelines) ● DevEx is bad - hard to maintain Why migrating to Microservices?
- 20. How small can a microservice be? How big a monolith can go?
- 21. Scaling #1: Horizontal scaling (stateless)
- 22. Scaling #2: Database read replica
- 23. Scaling #3: Data partitioning - Sharding (Z axis)
- 25. Summary Level 1: Monolith First & The right design! Level 2: Horizontal scaling Level 3: Database read replica Level 4: Database sharding Level 5: Microservices - conscious decision!