itsual Feature Flag Architecture
Overview
Feature flags decouple deployment from release and enable safer delivery. They also add complexity and must be managed deliberately.
When to Use
- Gradual or percentage rollouts
- Experiments and A/B tests
- Kill switches for risky features
- Trunk-based development with incomplete features
Design Principles
- Short-lived flags are preferable to permanent ones
- Name flags clearly and include ownership/expiry information
- Avoid flag dependency spaghetti
- Clean up flags after full rollout or experiment conclusion
- Consider performance and consistency implications of flag evaluation
Operational Checklist
- Flag has a clear owner and expected lifetime
- Default value is safe
- Monitoring exists for the new behavior
- Removal plan exists
- Evaluation points are consistent (especially in distributed systems)
Verification
- Flags can be toggled without redeploying (where intended)
- Stale flags are tracked and removed
- Experiments have clear success metrics and end conditions