Feature flags, also known as feature toggles or feature switches, are a software development technique that allows developers to turn features of an application on or off without having to redeploy the entire codebase.
This technique can be useful for several reasons. It allows for greater control over the features of an application, enabling developers to test new features in a live environment without affecting the overall user experience. feature flags can also be used to gradually roll out new features to a subset of users, allowing for A/B testing and user feedback before a full release.
Moreover, feature flags provide a safety net for developers. If a new feature causes unexpected issues, it can be quickly turned off without having to roll back the entire deployment. This ability to quickly react to problems helps to keep applications stable and reliable, even during the development process.
Feature flags work by wrapping a new feature in a conditional statement that checks the status of a flag. If the flag is set to ‘on’, the feature is enabled. If the flag is set to ‘off’, the feature is disabled.
This may sound simple, but the implementation can be complex. The flags can be stored in a variety of ways, including in the application code, in a database, environment/configuration file, or in a dedicated feature flag management system.
The flags can also be controlled at various levels. For example, they can be set globally, affecting all users, or they can be set at the user level, allowing for individual customization. The level of control depends on the requirements of the application and the desired user experience.
See how to manage feature flags with Frontegg Entitlements
Here are some of the common use cases for feature flags in software development:
Feature flags are a powerful tool for managing software releases. They allow for continuous integration and continuous delivery (CI/CD), enabling developers to release updates and new features quickly and efficiently.
With feature flags, new features can be rolled out to a small group of users for testing before being released to all users. This can be particularly useful for A/B testing, where two different versions of a feature are tested to see which performs better.
Feature flags can significantly improve the reliability and operational health of an application. By providing a way to quickly disable problematic features, they help to maintain stability and prevent disruptions to the user experience.
Furthermore, feature flags can be used to implement a ‘kill switch’ for new features. If a new feature is causing problems, it can be quickly disabled without affecting the rest of the application.
Feature flags can also be used to create personalized software experiences. By enabling or disabling features for specific users or user groups, developers can tailor the application to meet the needs and preferences of individual users.
This can be particularly useful for businesses that have a diverse user base with different needs and preferences. With feature flags, they can create a unique experience for each user, improving user satisfaction and engagement.
Lastly, feature flags can be used to reduce the risk of migrations. Migrating an application to a new platform or technology can be a complex and risky process. If something goes wrong, it can cause significant disruption to the user experience.
With feature flags, developers can gradually migrate users to the new platform or technology. This can be done by enabling the new platform or technology for a small group of users, testing it thoroughly before gradually rolling it out to all users.
Here are examples showing a simple implementation of feature flags in several common programming languages.
Use Case: Dynamic feature visibility in a dashboard.
In a React application, assume we have a dashboard where certain features are available only to premium users. We want to control the visibility of these features using feature flags.
Example code:
In this example, useFeatureFlag is a custom hook that checks if the premiumFeature flag is enabled. If it is, the PremiumFeature component is rendered.
useFeatureFlag
premiumFeature
PremiumFeature
Learn more in our detailed guide to feature flags react (coming soon)
Use Case: Experimenting with different recommendation algorithms
In a Python web service, we want to experiment with different recommendation algorithms to see which performs better.
Here, feature_flag.is_enabled(‘newAlgorithm’) determines which algorithm to use based on the status of the newAlgorithm feature flag.
Learn more in our detailed guide to feature flags Java (coming soon)
Use Case: Gradual rollout of a new UI
In a JavaScript (Node.js) application, we have a new user interface that we want to gradually roll out to users.
In this scenario, featureFlagService.isEnabled(‘newUI’, req.user) checks if the newUI feature flag is enabled for the requesting user.
Learn more in our detailed guide to js feature flags (coming soon)
Use Case: Feature-specific access control
In an Angular application, there’s a need to control access to a new reporting feature based on user roles.
Learn more in our detailed guide to feature flags angular (coming soon)
Use Case: Beta features in a mobile app
In an Android app, we want to enable beta features for a select group of users to gather feedback.
FeatureFlagManager.getInstance().isFeatureEnabled(“betaFeature”) checks the status of the betaFeature flag and determines whether to enable it for the current user.
Learn more in our detailed guide to feature flags Android (coming soon)
Planning and documenting your feature flags ensures that your feature flags are implemented correctly and efficiently, and that they are easy to understand and manage.
Planning your feature flags involves defining the purpose and scope of each feature flag, and determining how and when it will be used. This can help to ensure that your feature flags are designed and implemented to meet your specific needs and objectives.
Documenting your feature flags involves maintaining a record of all your feature flags, including their purpose, status, and usage. This ensures feature flags can easily be audited or reviewed if necessary.
Limiting the lifespan of feature flags can help prevent the accumulation of technical debt. Keeping feature flags around longer than necessary can lead to increased complexity and potential system failures.
One way to limit the lifespan of feature flags is to set a predefined expiry date for each feature flag. After this date, the feature flag should be removed from the codebase. This can help to ensure that your codebase remains clean and maintainable. This is typically automated in feature flag management systems.
Integrating feature flags with your CI/CD pipeline allows you to control and manage the lifecycle of your feature flags. It can also help to ensure that only tested and approved flags are deployed to production, reducing the risk of errors or failures.
Integrating feature flags with your CI/CD pipeline can also enable you to automate the process of feature flag management. For example, you can automate the process of turning on or off specific feature flags based on predefined criteria or triggers. This can help to ensure that your feature flags are always in the correct state and that they are updated promptly when changes are made.
Monitoring and analyzing feature flag usage can help you to understand how your feature flags are being used, and to identify any issues or opportunities for improvement.
Monitoring feature flag usage can help you to identify any unusual or unexpected activity, such as a sudden increase in the usage of a specific feature flag, or a feature flag that is being used by a large number of users. This can help you to quickly identify and address any potential issues or risks.
A centralized feature flag management system can provide a single source of truth for all your feature flags, ensuring that they are consistent and up-to-date across all your environments.
A feature flag management system can also help to simplify the process of managing and maintaining your feature flags. It can provide you with a user-friendly interface for creating, updating, and deleting feature flags. It can also provide you with tools for managing the lifecycle of your feature flags, such as the ability to schedule the activation or deactivation of feature flags.
Furthermore, a centralized feature flag management system can provide you with advanced features and capabilities, such as the ability to segment your users based on various criteria and to target specific user segments with different feature flags.
Learn more in our detailed guide to feature flags best practices (coming soon)
Frontegg offers a self-served user management platform, empowering seamless scalability. Its scalable multi-tenant architecture handles backend needs, while also addressing frontend requirements like login flows and customizable sign-up boxes. With Frontegg Entitlements, you can now manage feature flags based on policy and ABAC, ensuring streamlined operations and enhanced security.
