Tech Talk - Feature Flags & Toggles

Tech talk at Marqeta on 03/21/2019 on Feature Flags and Toggles.

Transcript

1. Feature Flags & Toggles Marqeta Tech Talks
2. Who? Manish Pandit Engineering
3. Title? Feature Flags == Feature Toggles
4. Feature Toggles Feature Toggles are a powerful technique, allowing teams to modify system behavior without changing code Source: https://martinfowler.com/articles/feature-toggles.html
5. Meh.. We’ve all used them
6. if (allowBackgroundRefresh) { initializeBackgroundRefresh(5, TimeUnit.SECONDS); }
7. if (logLevel == LogLevel.DEBUG) { Console.log(“This should not be here”); }
8. if (referenceNumber%2==0) { return shard1; } else return shard2;
9. Deconstructing a Feature Toggle Toggle Configuration = on/off | env | user id(s) | geo | time | …. (Stored in config-file | database | env-var | in the code | FTaaS) Toggle Context = env | user id(s) | geo | time | logged-in-state | tenant-id | … Toggle Router = reads the toggle configuration + context to determine which toggle point to activate Toggle Point = execution path(s) for the toggle state(s)
10. Think about it! Does the storage location of a Toggle Configuration affect when it can be toggled?
11. Think about it! Does the storage location of a Toggle Configuration affect when it can be toggled? build | deploy | startup | runtime
12. Types of Feature Toggles
13. Release Toggles
14. Release Toggles
15. Release Toggles Decouple releases from deployments Referred a lot in the context of Continuous Integration (CI) Allow for large feature branches to be merged in master Long lived (based on how long the feature branches take - weeks? months?)
16. Experiment Toggles
17. A/B Testing
18. Experiment Toggles Used to gather data to help pick the right feature (Mostly) used with end user interaction use cases (Can also be) used to tune system performance Short lived (weeks)
19. Operational Toggles
20. Operational Toggles Used to turn off features to control unknowns/unexpected Almost exclusively used in Production Short lived (days) till a baseline is established Can be lifetime (kill switches!) Help with graceful degradation
21. Permission Toggles
22. Permission Toggles Used to change behavior for a partial set of users May need to evaluate the user authorizations Canary, or incremental rollouts Beta, Early Adopters (or Early Winners as we call ‘em!) Can be very short (hours) or long (lifetime) lived
23. Summary Source : https://martinfowler.com/articles/feature-toggles.html
25. Pick the right place to store the toggle configuration (Ask the audience if they remember the storage options!)
26. Do not name your toggles after pets, food, places..you get the point Follow a naming convention
27. Use feature flags in moderation, use your best judgement
28. Feature flags can turn into technical debt real quick - delete them once not in use. Hint : If a transient flag has been in the same state for a long time, it is not needed.
29. Have an audit trail of any changes to Toggle configuration - treat it like sensitive data
31. Let the experts do it for us!
32. Launchdarkly Feature Management as a Service https://launchdarkly.com/
37. Don't worry, these keys are duds by the time you’re seeing ‘em :)
43. Resources Feature Toggles (aka Feature Flags) : https://martinfowler.com/articles/feature-toggles.html When Feature flags go bad - Edith Harbaugh : https://www.youtube.com/watch?v=28ZAoStv-Xw Getting Started with Feature Flags - #1 LaunchDarkly Feature Flags : https://www.youtube.com/watch?v=pwA_Ehp2SMY
44. Fin.