A caveat on Feature Flagging

Release flags are the last thing you should do

WARNING

See Knightmare A DevOps Cautionary Tale on the risk of having dead code in a complex codebase

If not kept in check:
- The codebase becomes more complex as
  - there’s many branches
  - you may not have context on why certain flags exists, or how it interacts with other flags
- Wasting time on dead code
  - Refactors have to account for dead code¹
- Testing becomes harder and longer due to more feature flags
  - You have to run more tests, and you may not cover everything. See How to test feature flags? for more info.
- A reason to build code that never gets released
  - This sums to poor planning though
- A reason to not remove code
It’s also a smell since it means that feature development are long running or aren’t completed, that’s why (release) flags are not removed
- Long running features ofc means that you aren’t making small frequent releases, nor are you getting good feedback from your users
Prioritize small releases or Keystone Interfaces over release flags