A Monolith on the Dissecting Table: The Strangler Fig Pattern in Action @ Devoxx Poland 2023

Abstract:

Many existing companies cannot just start over on the green field. Instead, significant maintenance efforts are necessary for aged applications, which usually exhibit a monolithic architecture based on traditional, potentially outdated tech stacks. Companies willing to shift towards distributed architectures and modern technologies are struggling because they don't know where and how to start.

This talk briefly introduces the strangler fig pattern, which enables a smooth and step-wise transformation of monolithic applications into separate (micro)services. The main focus of this practical session is a demo scenario, showing step-by-step how to extract a particular part of an existing monolith into a separate service. During the demo, we will also get in touch with popular technologies such as Kubernetes, Apache Kafka, Debezium, and MongoDB.

This session helps you to understand what it means to apply the strangler fig pattern to extract functionality from your monoliths. The learnings will empower you to gradually evolve existing applications into a (micro)service architecture and an en-vogue tech stack.

Demo Repository: https://github.com/hpgrahsl/sfp-devoxxpl23

Video Recording: https://www.youtube.com/watch?v=ty3pdFQgSRg

Transcript

1. A Monolith on the Dissecting Table: The Strangler Fig Pattern in Action @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023
2. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 2
3. ! It's me ... Hans-Peter • Developer ! Advocate @ Red Hat • Open-Source Enthusiast • 4x Confluent Community Catalyst • MongoDB Champion since 2020 • based in Graz, Austria " @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 3
4. system migrations are challenging @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 4
5. ! What about the big rewrite and a hard cut-over? ! @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 5
6. BIG BANG migrations often doomed to failure @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 6
7. "If you do a big bang rewrite, the only thing you're certain of is a big bang." — Martin Fowler @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 7
8. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 8
9. Migration Goal • gradually evolve from old into new • support (temporary) coexistence • avoid risky big bang rewrite @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 9
10. strangler fig pattern to the rescue @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 10
11. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 11
12. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 12
13. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 13
14. strangler fig pattern by example @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 14
15. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 15
16. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 16
17. Change-Data-Capture @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 17
18. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 18
19. Debezium's supported Databases @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 19
20. Open-Source Change-Data-Capture • captures data changes by tapping into DB's TX log • change events propagated via Apache Kafka / Connect @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 20
21. Open-Source Change-Data-Capture • captures data changes by tapping into DB's TX log • change events propagated via other messaging systems @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 21
22. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 22
23. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 23
24. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 24
25. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 25
26. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 26
27. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 27
28. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 28
29. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 29
30. CDC Pipeline Concern #1 We're leaking our data / domain model. I want an anti-corruption layer. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 30
31. Single Message Transforms @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 31
32. Single Message Transforms @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 32
33. CDC Pipeline Concern #2 But this only replicates data "row by row". I might need aggregate structures. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 33
34. Stream Processor for Joining @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 34
35. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 35
36. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 36
37. Wrapping Up • incremental migration → baby steps • pause / stop without losing spent $$$ • extraction steps ideally reversible @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 37
38. ⚠ minimize migration risk @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 38
39. Let's stay in touch! ! @hpgrahsl @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 39
40. ! Give it a try! " • Strangler Fig Pattern Demo https://bit.ly/sfp-devoxxpl23 @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 40
41. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 41
42. Links & Resources • Demo Repository https://github.com/hpgrahsl/sfp-devoxxpl23 • Developer Sandbox for Openshift https://developers.redhat.com/developer-sandbox • Debezium Website https://debezium.io • Quarkus https://quarkus.io @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023 42
43. @hpgrahsl | #DevoxxPL - Kraków, Poland | 2023