Feature Flags

[fee-cher flagz]

Feature flags (also known as feature toggles or feature switches) are configuration settings that allow developers to modify system behavior without changing code. They serve as a powerful tool in modern software development, enabling teams to control feature rollouts, conduct experiments, and manage code deployment risks.

How Feature Flags Work

Feature flags operate as conditional statements in code that determine whether specific functionality should be enabled or disabled. These conditions can be as simple as boolean values (true/false) or as complex as sophisticated rules based on user attributes, time, location, or other parameters.

if (featureFlags.newNavigation.isEnabled) {
    // Show new navigation
} else {
    // Show old navigation
}

Implementation at CRFT Studio

At CRFT Studio, we use PostHog as our feature flag management system. It provides a robust platform for creating and managing feature flags across our projects. The platform allows us to:

Create and manage feature flags through an intuitive dashboard
Set up sophisticated targeting rules based on user properties
Monitor feature flag usage and impact through analytics
Implement multivariate testing with multiple flag variants
Integrate seamlessly with our existing development workflow

// Example of PostHog feature flag implementation
if (posthog.isFeatureEnabled('new-checkout-flow')) {
    // Show new checkout experience
} else {
    // Show original checkout flow
}

Key Benefits

Controlled Feature Rollouts

Feature flags enable gradual feature releases through techniques like canary releases or percentage rollouts. Teams can release features to a small subset of users first, monitoring performance and gathering feedback before wider deployment.

Risk Mitigation

By wrapping new features in feature flags, teams can quickly disable problematic functionality without rolling back entire deployments. This capability provides a safety net for production issues and reduces deployment risks.

A/B Testing

Feature flags facilitate experimentation by allowing teams to show different versions of features to different user segments. This enables data-driven decision-making based on user behavior and preferences.

Development Workflow

Teams can practice trunk-based development more effectively by using feature flags to hide incomplete features in production. This allows for continuous integration while maintaining a stable user experience.

Best Practices

Naming and Documentation

Feature flags should follow consistent naming conventions and be well-documented. This includes their purpose, intended lifespan, and any dependencies they might have.

Lifecycle Management

Regular cleanup of obsolete feature flags is crucial to prevent technical debt. Teams should track flag usage and remove them once features are fully launched or experiments are concluded.

Implementation Considerations

Feature flags should be implemented with proper error handling and fallback mechanisms. They should also be designed to have minimal impact on application performance and maintainability.

Common Use Cases

Dark Launches: Testing features in production with internal users
Progressive Rollouts: Gradually releasing features to increasing numbers of users
Kill Switches: Quickly disabling problematic features
User Segmentation: Providing different experiences to different user groups
Beta Testing: Limiting new features to specific user segments for feedback

Feature flags have become an essential tool in modern software development, enabling teams to deploy with confidence, experiment safely, and maintain greater control over their applications’ behavior in production environments.