This Old Pony: Working With Legacy Django Apps

on YouTube ↗31m

" summary

Defines legacy as code in production often lacking tests and clarity and recommends concrete steps: do a disciplined code review with flake8 and PyCharm, add logging before tests (Sentry for stack traces), write bug-reproducing and smoke tests, silence flaky tests, speed slow suites, and use tox to test multiple Django versions aiming for an LTS. Handle dependency breakage by patch and PR or vendoring forks, run Bandit for secrets, and incrementally refactor big apps (move models with Meta db_table, push view logic into managers).

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" chapters (40)

1. 0:00Start
2. 0:42Legacy software?
3. 1:11What is "legacy"?
4. 1:24Code someone else wrote
5. 1:47Code that has no tests
6. 2:12Software that's in production
7. 2:42Written software is an investment
8. 2:59Ugly, old systems deliver value
9. 3:16The world runs on legacy software
10. 3:27What is legacy Django?
11. 4:31Some assumptions
12. 5:08Goal: improve code in discrete steps
13. 6:57Step 0: Ask questions
14. 7:11What's it supposed to do? What does it do? Known bugs? Planned features?
15. 7:34Reading the code
16. 7:45Confusing areas Architecture Code smell Style &c.
17. 9:35Understand production errors
18. 11:14Fix bugs Guide development Deployment confidence
19. 11:36Tests provide information about code quality.
20. 11:49Test suite scenarios
21. 15:30Prioritizing new tests
22. 16:01Smoke tests View-centric integration tests
23. 16:42Refactoring
24. 17:13Backwards incompatibilities
25. 17:32Superpower: tox
26. 19:18Tight integration with obsolete libraries
27. 19:45Version support mismatches
28. 20:14Upgrade!
29. 20:29Patch and pray (upstream)
30. 21:32Extract what you used
31. 22:02Remove/replace
32. 22:48Formatting
33. 23:33Settings
34. 24:20One big app
35. 24:31Solution: Break up apps
36. 25:01Big views (lots o' logic)
37. 25:19Fat models
38. 25:40Expansive forms
39. 26:24New feature? New app!
40. 26:34What didn't we talk about?

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