Feature Toggles
Feature Toggles are mechanisms that allow developers to enable or disable functionality in a software application dynamically. This can be done without changing the code and can be controlled through external configuration.
Purpose
Feature Toggles serve several purposes, including enabling continuous delivery and integration, allowing for testing of new features in a production environment with limited exposure, and supporting different feature sets for different users or environments.
Feature Toggle Maturity
Feature toggles refer to the last two stages of the feature flag maturity model. At lower levels, rather than being dynamic, the flags are static and require a deployment to change their state.
| Maturity Level | Implementation Description | Tools/Approaches |
|---|---|---|
| Basic | Simple if-else statements directly in the code. This approach is quick to implement but can become hard to manage as the number of flags grows. | Native code, no specific tools. |
| Intermediate | Feature flags are centralised in a configuration file or a database. This allows easier management compared to the basic level but lacks advanced targeting and analysis. | Configuration files, custom databases. |
| Advanced | Utilisation of a dedicated feature flag service or platform that offers targeting, canary releases, and A/B testing capabilities. | LaunchDarkly, Split.io, Unleash, Optimisely. |
| Enterprise | Advanced systems with additional features such as real-time flag updates, full user targeting, percentage rollouts, experiment tracking, and comprehensive analytics. | LaunchDarkly, Split.io, with custom integrations and extensive analytics platforms. |
Anti-patterns
- Toggle Creep: Accumulating too many feature toggles in the system without removing them once they serve their purpose.
- Complex Dependencies: Creating toggles that depend on other toggles, which can lead to unpredictable behaviour.
- Failure to Remove: Not removing toggles once they are no longer needed, leading to technical debt and increased complexity.