--- title: "Type-safe feature flagging in openfeature: Lessons learned from using feature flags at google" weight: 2 tags: - kubecon - dev --- {{% button href="https://static.sched.com/hosted_files/kccnceu2025/f6/Type-safe%20Feature%20Flagging%20in%20OpenFeature.pdf" style="tip" icon="person-chalkboard" %}}Slides{{% /button %}} ## Featureflags? - Idea: Change the behaviour of an application without rebuilding it - Goal: Control rollout, reduce risk, experiment (a/b) - At google: A huge number of feature flags (150k+) but that's because people forget to turn them off ## Where does the flag come from - Lifecycle of a flag: Create, Manage, Deprecate, Delete -> But will it be created frist in code or in the service - Classic implementation: Just a if/else that uses a function to get the flag - Problem: What if the flag names missmatch between the code and flag ser -> Muliple sources of truth - Solution: Require use of auto-generated flag bindings (codegen from the management system) to mitigate typos, etc. ## OpenFeature - Goal: Vendor agnostic, standardized, open source - Basic setup: Register provider (once per app), create a client, use client to get flags - CLI: Integrate into management system, keep a local manifest of all flags and generate code (generates the client) - Now: Just call the client's method instead of hard-coding feature flag names