How to rewrite, a bit at a time - Pipeline Conference 2018

There’s nothing more frustrating than not being able to deliver new features because of unnecessarily complicated code. A fast deployment pipeline is of no use if the code itself is too hard and slow to change.

You may decide it’s time to throw it all away and start over… and what began full of optimism, drags on for months and years, adding even more complexity and various levels of legacy.

It doesn’t have to be this way! In this presentation, you’ll hear a first-hand experience of how to approach technical debt in an iterative way. This talk will teach you lessons on how to start, and most importantly, finish a big rewrite project.

You will learn how to approach the conversation with the “business”, avoid the most common pitfalls when changing the architecture of a complex codebase, and ensure the rewrite brings value from the start till the very happy end.

Transcript

1. How to rewrite, a bit at a time Sabrina Leandro @saleandro Pipeline Conference 2018
2. Rewrites at Songkick
3. Rewrites at Songkick 1. Songkick.com 2. Tickets store 3. Internal tools
4. BIG REWRITE STRIKES AGAIN
5. • The problem • How to start a rewrite project • How to run it • How to finish it • How to not need it again! This talk
6. Stop me if you think you’ve heard this one before The problem
7. 10101 11001
8. 10101 11001 1010111001101 0111001100111 0011100111001 1001110011100 1110001010111 0011100111001
9. Software Entropy 10101 11001 1010111001101 0111001100111 0011100111001 1001110011100 1110001010111 0011100111001
10. Complex abstractions Lots of features Too many slow tests Little to no tests No clear abstractions Lots of features
11. Complex abstractions Lots of features Too many slow tests Little to no tests No clear abstractions Lots of features Tickets store & Internal tools
12. Complex abstractions Lots of features Too many slow tests Little to no tests No clear abstractions Lots of features Songkick.com Tickets store & Internal tools
14. How to start it
15. •Is it the right time? •Is it the right reason?
16. Is it the right time? Discovery vs Delivery
17. Is it the right time? Yes, if the product has a clear business value today.
18. Is it the right reason? What difference does it make?
19. Is it the right reason? Yes, if there’s one clear business case.
20. PLEASE PLEASE PLEASE Let me get what I want
21. How to sell it Have one clear business case
22. How to sell it Show what a great new world it will be!
23. How to sell it Find allies outside of your team
24. Make the pain visible How to sell it
25. How to sell it Do Repeat Yourself
26. How to sell it Do Repeat Yourself Do Repeat Yourself
27. How to run it
28. Technical vision and strategy Now The future!
29. Technical vision and strategy Now The future! Steps to get there ???
30. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application
31. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application
32. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application Legacy application
33. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New Legacy application
34. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New Legacy application Legacy application
35. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New Legacy application Legacy application New application
36. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New New application Legacy application Legacy application New application
37. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New New application Legacy application Legacy application RIP Legacy application New application
38. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New New application VALUE Legacy application Legacy application RIP Legacy application New application
39. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New Legacy application Legacy application New application
40. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New Legacy application Legacy application New application Legacy application
41. “Rewrite from scratch: Waterfall process of rewrites
42. The strangler application
43. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
44. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
45. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
46. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
47. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
48. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
49. Team 1: Maintaining legacy and building new application New applicati Now Bright future! Rewrite using strangler
50. Team 1: Maintaining legacy and building new application New applicati Now Bright future! Rewrite using strangler
51. Team 1: Maintaining legacy and building new application New applicati Now Bright future! Rewrite using strangler
52. Team 1: Maintaining legacy and building new application New applicati Now Bright future! Rewrite using strangler
53. Team 1: Maintaining legacy and building new application New applicati VALUE! Now Bright future! Rewrite using strangler
54. /orders /customers
55. /orders /customers new/customers
56. /orders /customers
57. /orders /customers Build Validate Replace Delete Repeat
58. “ Deleting is faster than rewriting
59. Bones Muscle Fat Cut features to move faster
60. “ If we were starting over, what would we build today, knowing what we know now?
61. During the project
62. How to run it Do one thing at a time
63. 1.Find the biggest blocker 2.Remove it completely 3.Repeat How to run it Warning: Step 2 might involve more than coding
64. How to run it Celebrate your successes!
69. That joke isn’t funny anymore… How to run it Do Repeat Yourself, again
70. How to finish it
71. How to finish it I started something I couldn’t finish
72. How to finish it These things 
 take time
73. How to not need it again
74. 10101 11001 1010111001101 0111001100111 0011100111001 1001110011100 1110001010111 Time… Software Entropy
75. How to not need it again Make the cost visible
77. DELETE
78. DELETE CODE
79. DELETE CODE FEATURES
80. DELETE CODE FEATURES PRODUCTS
81. “ If we were starting over, what would we build today, knowing what we know now?
82. Make it part of your day-to-day How to not need it again
83. “ A refactor a day keeps the rewrite away!
84. How to not need it again A little bit and often
85. How to not need it again Get used to inconsistencies
86. Technical migrations Continuously deliver value Delete what’s not valuable One business goal
87. Sustainable Software Make maintenance cost visible Learn and collaborate Refactor a little bit and often
88. Thanks! Sabrina, take a bow… sabrina@saleandro.com @saleandro
89. Bigmouth Strikes Again This Charming Man Stop Me If You Think You’ve Heard This One Before What Difference Does It Make? Please, Please, Please, Let Me Get What I Want That Joke Isn’t Funny Anymore I Started Something I Couldn’t Finish These Things Take Time Sheila Take A Bow Thanks! Sabrina, take a bow… sabrina@saleandro.com @saleandro
90. Songkick.com rewrite • https://devblog.songkick.com/the-path-to-soa-d986a18d4a8b • https://devblog.songkick.com/our-object-based-rails-frontend-3e2ddc048d12 • https://www.youtube.com/watch?v=-VEf8j6aGMk • https://www.martinfowler.com/bliki/StranglerApplication.html Celebrate your successes • https://medium.com/@Songkick/gamify-your-product-team-to-power- level-9000-261e9fceaa22 Hoarders metaphor / Liveable code • https://twitter.com/sarahmei/status/783115752794492928 • https://www.youtube.com/watch?v=mz3l_oEA2cU • https://twitter.com/kentbeck/status/856537528886673408 Product discovery and product delivery • http://jpattonassociates.com/dual-track-development/ • https://martinfowler.com/bliki/DesignStaminaHypothesis.html • https://www.facebook.com/notes/kent-beck/teams-in-3x/1244519748914220/ References
91. References Make the cost visible • http://codemanship.co.uk/parlezuml/blog/?postid=1433 • http://blogs.msdn.com/b/elee/archive/2009/03/11/source-code-is-a-liability-not-an- asset.aspx Make it part of your day-to-day • https://martinfowler.com/bliki/OpportunisticRefactoring.html • http://ronjeffries.com/xprog/articles/refactoring-not-on-the-backlog/ • http://firstround.com/review/forget-technical-debt-heres-how-to-build-technical- wealth/ • https://www.infoq.com/presentations/microservices-replaceability-consistency • https://www.sandimetz.com/blog/2017/6/1/the-half-life-of-code • https://www.infoq.com/presentations/remove-unneeded-code Playlist :) • https://open.spotify.com/user/saleandro/playlist/6i3RVHtys4djlYlLLGZc26