1. The document discusses using Buck as a build system for an app with multiple developers working on different components across several apps that need to share code. 2. Buck provides advantages over other solutions like Xcode by automatically managing shared modules, caching builds for faster rebuilds, and only rebuilding components that were changed in a pull request. 3. The company iFood migrated from Xcode to Buck and saw build times drop from over 30 minutes to under 10 minutes for pull requests by leveraging Buck's caching and ability to only test the affected parts of the code graph.

1. Buck Build outside
Silicon Valley
Bruno Rocha - Software Engineer
+

3. Tons of developers
Several apps that share components
Giant codebases
Developers work in very localized squads
(localized changes)
Valley Companies
Ability to create
internal helper tools

5. iFood
1. 40+ Developers
2. Four apps that need to share components
3. Developers work in very specialized squads
4. Most pull requests are very localized

6. .pbxproj con
fl
icts

7. Maintaining modules is hard

8. Huge build times

9. No project con
fl
icts
Automatic management of modules
Easy way to share components
between projects
Build only what was changed,
both locally and in the CI
All apps in one repo
Valley Companies

10. Monorepo
Build Systems

11. Bazel Build
Buck Build
Monorepo Build Systems

12. App
App Splash
Checkout Pro
fi
le
Login Architecture
Client Keychain
…
More modules
= less builds!

13. Multirepos vs Monorepos
App A
Repo 1
App B Library C
Repo 2 Repo 3
App A
Repo 1
App B
Library C

14. App A
Project A
App B
Project B
Library C Library C
Builds Library C, then App A Builds Library C again, then App B

15. Builds Library C, then App A Builds App B only
//MyApps:AppA
Projects A/B
//MyApps:AppB
//MyLibs:LibraryC

16. Buck Caches (Rulekeys)
//MyLibs:LibraryC
Hash of dependencies
Compiler
fl
ags
Compiler version
Buck version
Source contents
3fb80a353db183675fd561b284bc5085

17. 💻
🤖
💻 💻
🤖 🤖
CI Builds
PR 1 PR 2 PR 3
30 minutes 30 minutes 30 minutes

18. 💻
🤖
💻 💻
🤖 🤖
CI Builds
PR 1 PR 2 PR 3
30 minutes 5 minutes 3 minutes
Cache Cache

19. 💻 💻 💻
🖥
Network Cache
Upload Cache Download Remote Cache

20. Creating iOS Apps
with Buck
Defining rules and using the build system

22. .buckcon
fi
g

23. Buck Rules (Libraries & Tests)

24. Building Libraries
//Libraries/uUserData:UserData
{root}{BUCK
fi
le path}{Rule name}

25. Build Trace
buck-out/logs/build.trace

26. Testing Libraries

27. App A
Library B
Library A
Library D
Library C
Saving time while testing
iFood with Xcode: All PRs tested all modules

28. App A
Library B
Library A
Library D
Library C
iFood with Buck: PRs only test the affected graph
Saving time while testing

29. Buck Rules (iOS Apps)

30. Building iOS Apps
buck install {rule} -r

31. Visual Studio Code + SourceKit-LSP + CodeLLDB

32. Xcode Project Generation

34. iFood’s Build/Test CI Evolution
Xcode: ~32 minutes
Buck + Cache: ~21 minutes
Buck + Cache + Only Test Graph: ~9 minutes

35. iFood’s .pbxproj Con
fl
icts Evolution
Xcode: All the time
Buck: None at all

36. iFood’s Modularization Evolution
Xcode: Create a podspec
Create an example project
Create the
fi
les
Add it to the pod
fi
le
Make our CI run the example’s tests
Hope changes won’t break the spec
Buck: Just create a folder!

37. airbnb/BuckSample

38. 😱
Buck Slack

39. #VemProiFood
+
swiftrocks.com
@rockthebruno
Obrigado!