Reflections on SCM: DevOps, CI/CD, Branches, Architecture, PRs, and many more considerations and thoughts.

1. Reflections on SCM
Diego Pacheco

2. @diego_pacheco
❏ Cat's Father
❏ Head of Software Architecture
❏ Agile Coach
❏ SOA/Microservices Expert
❏ DevOps Practitioner
❏ Speaker
❏ Author
diegopacheco
http://diego-pacheco.blogspot.com.br/
About me...
https://diegopacheco.github.io/

3. Every company works with Branches

4. Git Made branches much less painful...

5. But do we think about the implications?
❏ How much they affect CI/CD ?
❏ How much they affect Refactoring?
❏ How much they create bottlenecks?
❏ How much they hide architectural complexity?
❏ They optimized for Local, remote, colarotation or what?

6. Back do Lean/Agile/DevOps Principles
❏ Increase Feedback into the system
❏ Reduce Feedback cycles
❏ Reduce Batch size (lower delta, lower risk)
❏ Increase deployment frequence
❏ Experiment often
… it’s branches aligned with that?

7. Branch by Abstraction
❏ Long lived Branches
❏ Easily can live for 2 weeks (1 Sprint) or even much longer
❏ Benefits: Easily to Pause or Cancel
❏ How to:
❏ Introduce Abstraction, Wrote a second implementation
❏ Enable to all, remove old, on/off switch

8. Branch per Release
❏ Team pushes to prod or regular schedule (Sprint, Monthly)
❏ Also will need to push bug-fix releases in between.
❏ Stable place since devs are still committing on Trunk
❏ CI/CD Teams don't use this technique.

9. Release form Trunk
❏ Teams with high release cadence release from Trunk.
❏ No Slow down in releases
❏ Branches can be created retroactively

10. CI/CD
❏ XP technique
❏ CI by definition is single integration Source.

11. Trunk Based Development
❏ How CI/CD High Performance DevOps teams Work!
❏ Incompatible with GitFlow
❏ Works best for fast interactions/releases and SR engineers.

12. GitFlow

13. GitFlow: Commit Races
❏ Lots of changes
❏ First to Commit win
❏ Also known as PR Races
❏ It happens !!!

14. Issues with Branches
❏ Don’ t encourage Refactoring (Harder Merges)
❏ Shallow Review: Fast LGTM
❏ Batch size Problem (Anti-Lean)
❏ No Real CI happening
❏ Core Team Vs External Contributors

15. Other alternatives to branches...

16. The Issue with Release Trains / Calendars

17. Github Flow

18. Git OPS

19. PRs, PP/Mob and Code Review
❏ PR can create “interruptions”.
❏ Branches are good for individuals and bad for teams.
❏ Pair Programing is Code Review (no need to submit a PR)
❏ PP/Mob help to share knowledge
❏ PP/Mob is much faster Feedback

20. Branches and Architecture
❏ Good Modular Architecture
dont require branches.
❏ Mobile Might require
branches by nature.
❏ Isolation is the ultimate
branch blast radius
reducer.
❏ Code is Dynamic, Branches
are static.

21. Wrapping Thoughts
❏ Branches and PRs are cheap and the norm today.
❏ Most of companies see CI/CD as tools and not as principles.
❏ It's common to see people that don't want increase deployment frequency.
❏ Good Architecture require less or no branching.
❏ High Frequency releases and gitflow don't match.
❏ Lower Delta, Lower Risk, Release Often, Get more feedback.

22. Reflections on SCM
Diego Pacheco