Tackling a Legacy Codebase with (Micro)Services

PyConUK 2015 presentation on tackling a legacy PHP codebase with microservices written in Python and Django REST Framework.

Talk is on YouTube at: https://www.youtube.com/watch?v=u1lO0JnIeFU

Transcript

1. Tackling A Legacy Codebase With (Micro)services John Chandler @john_chandler
2. Nevermind the Monolith, Here's the Microservices
4. • Amazing Scalability! • Revolutionises Development! • Eliminates Poverty! • Resolves EMACS vs VI!
5. Continuous Deployment Containers Bounding Contexts 12 Factor Apps Unicorns
6. Continuous Deployment Containers Bounding Contexts 12 Factor Apps Unicorns
7. • Encourages loose coupling • Encourages smaller codebases • Encourages better "devops" • One way to tackle a legacy monolith
8. Part I: In The Beginning
9. https://www.flickr.com/photos/shutterbc/420672735/ (Not The Actual Developer)
10. https://www.flickr.com/photos/40726522@N02/4811009710/ (Not The Actual Pizza)
11. (Not The Actual Product) https://commons.wikimedia.org/wiki/File:Taj_Mahal_in_March_2004.jpg
12. https://www.flickr.com/photos/digitalsadhu/2627835068/ (Actual Product)
13. Part II: The Rewrite
14. Web Framework (PHP Zend - don't ask) REST API (Piston) Message Queueing (RabbitMQ) ORM (SQLAlchemy) Database (Postgresql)
15. Web Framework (PHP Zend) REST API (Piston) Message Queueing (RabbitMQ) ORM (SQLAlchemy) Database (Postgresql)
16. Is It Done Yet? (Not Yet)
17. Web Framework (PHP Zend) REST API (Piston) Message Queueing (RabbitMQ) ORM (SQLAlchemy) Database (Postgresql)
18. Is It Done Yet? (No, Not Yet)
19. Web Framework (PHP Zend) REST API (Piston) Message Queueing (RabbitMQ) ORM (SQLAlchemy) Database (Postgresql)
20. Okay, that's enough.
21. (90% done!)
22. (It's just missing a few things...)
23. Part III: Salvage Rights
24. Web Framework (Django + AngularJS) REST API (Piston, then Django REST Framework) Message Queueing (RabbitMQ) ORM (SQLAlchemy) Database (Postgresql)
25. Web Framework (Django + AngularJS) REST API (Django REST Framework) Database (Postgresql)
26. Web Framework (Django + AngularJS) REST API (Piston, then Django REST Framework) Message Queueing (RabbitMQ) ORM (SQLAlchemy) Database (Postgresql)
27. https://www.flickr.com/photos/nasahqphoto/7986344024/
28. Part IV: A New Hope (Apologies. I couldn't resist)
29. It's a shame you can't just swap bits out
30. Search Media Emails Users PDF Generation Forums Dragons Spiders WTF (Gross oversimplification)
31. Find A Feature
32. Search Media Emails Users PDF Generation Forums Dragons Spiders WTF
33. https://www.flickr.com/photos/armymedicine/6300225700/
34. Search Emails Users PDF Generation Forums Dragons Spiders WTF Media API
35. Then Scale Up
36. Media API Media API Load Balancer + Cache
37. (IT can deliver!)
38. Repeat Until Done
39. Not everything will be perfect first time
40. But it will improve over time
41. And small services are cheap to discard
42. • Small Steps • Consider Value • Minimise Technology • Monitor Complexity
43. Go tackle that monolith!