More commonly referred to as feature flags, a feature toggle is essentially a snippet of code that acts as a kill switch to enable or disable a feature within a software application’s codebase.

Feature Toggles are powerful. They allow developers to switch specific features of an application on or off without having to re-deploy code into the production environment. This capability has use cases for testing, targeted feature rollout, quick rollback, experimentation, canary releases, and managing operations or premium features.

Specifically, feature toggles allow for the activation or deactivation of code paths in real-time, enabling developers to adjust features based on current needs or user feedback without waiting for a formal release cycle.Implementing feature toggles can range from simple, low-tech methods like configuration files to more sophisticated approaches involving comprehensive feature flag management systems. Feature flag management systems provide a user interface that manages every aspect of toggle configuration, simplifying the process for development teams.

Why Use Feature Toggles?

Feature toggles provide a range of strategic benefits in software development, offering enhanced control over code deployment and feature management. Here are some ways they can help engineering teams and product managers enhance both the development process and operational management.

Flexibility in Release Management

Feature toggles allow development teams to manage precisely when a feature is introduced to users, providing significant flexibility in planning and executing releases. This capability is essential for aligning feature releases with business objectives and market conditions without redeploying the entire application.

Risk Reduction

Toggles significantly reduce the risk associated with direct changes to the production environment by enabling and disabling features without deploying new code. This feature flipper method minimizes potential disruptions and ensures the user experience remains consistent and reliable.

Targeted Rollouts and Rollbacks

Toggles facilitate phased rollouts, allowing teams to introduce new features to select user groups before a full-scale launch. If a feature needs debugging, the same toggle allows for a quick rollback without any changes to the source code. These seamless rollbacks minimize user impact while improving real-world feedback for the developer team, and they are all manageable at runtime.

Experimentation

Feature toggles enable testing in the production environment. Toggles are a great way to implement A/B testing and other forms of experimentation. By selectively enabling features for a subset of the user base, developers can gather critical data on groups of users’ behavior and preferences.

Permission-based Toggling

Feature toggles can also effectively manage user permissions and control access to specific features within an application. This method is especially useful in multi-tenant environments where different users or user groups require access to different sets of features.

• User Segment Targeting: Feature toggles can be configured to control which features are available to which segments of the user base. For example, premium features might only be enabled for paying customers, or experimental features might only be shown to users who have opted into beta tests.
• Dynamic Feature Management: Instead of hard-coding the permissions into the application, toggles allow for dynamic feature access management. Changes can be made quickly and efficiently through the feature management dashboard without any code changes to the deployments.
• Customizable User Experiences: Companies can customize the application experience for different users by using permission-based toggling. This customization can increase user satisfaction and engagement, as features can be tailored to meet the needs and expectations of specific user groups.

Resource Management

Toggles also have operational and administrative purposes. Ops toggles, as they are sometimes called, can temporarily deactivate resource-hungry features when the system is experiencing heavy loads or has reduced bandwidth due to maintenance. This functionality helps optimize system performance and resource usage without affecting overall service availability.

This list of toggle benefits demonstrates how powerful the tool can be. Every DevOps team is looking for better ways to support rapid deployment and high system stability. Feature toggles support those goals. The benefits of using toggles to decouple deployment from feature releases can positively impact production cycles. Teams that use toggles can focus on development efforts without worrying about destabilizing the backend and production environments. Now that you understand how to use toggles let’s discuss some tips for better toggle implementation.

Implementing Feature Toggles

While some simple, open-source options can be used as one-off tools, effective toggle implementation is a bit more sophisticated. Feature flag management is at its best when it is integrated with your software delivery infrastructure.

Configuring Toggles

When configuring feature toggles, it’s crucial to understand the system’s setup and the strategies you can employ to manage these toggles effectively. Let’s explore some key considerations and methodologies for configuring feature toggles to maximize their benefits.

1. Choosing the Right Type of Toggles

Feature toggles can be categorized into various types based on their purpose and longevity. Some common types include:

• Release Toggles: Control the release of features to users, allowing for phased rollouts and easy rollback in case of issues.
• Experiment Toggles: These are used for A/B testing to determine the effectiveness of new features.
• Ops Toggles: Provide operational control over features, allowing quick enable/disable actions in response to system performance or security concerns.

Organizing these types of toggles by tagging them with the above types, or using a status field to track the current role of a toggle is helpful, as it impacts how the feature will be managed and its lifecycle within your deployment processes.

2. Storage of Toggle Configuration

The initial implementation of feature toggles tends to start with simple config files or environment variables. However, as your application and feature complexity grow, these methods can become cumbersome and less scalable. Consider the following for scalable configuration:

• Database Storage: For more dynamic control, storing feature flags in a database allows you to change toggle states without deploying new code. Ensure that the database solution scales with your user base and feature complexity. Bear in mind that the progressive delivery use cases for flags require much more than a single “on” and “off” state, but rather a per-user or per user segment state.  That equates to an entry in a user profile or user cohort table, if available.
• Centralized Management: Use a dedicated feature flag management tool, like Split, that centralizes the configuration and provides a single source of truth. This approach facilitates easier updates and monitoring of flag statuses across all environments. Dedicated management tools also simplify the integration of SDKs, APIs, and other helpful tools.

3. Configuration Patterns

When configuring feature toggles, establish clear patterns that ensure consistency and ease of understanding across your team. Some effective patterns include:

• Naming Conventions: Implement consistent naming conventions that reflect the toggle’s scope and impact or purpose, such as frontEnd_showChatBot, which would control whether a chat bot appears on the front end or `backEnd_aiModelConfig` which control which AI model version is run and what config, including prompts, it is fed. 
• Segmentation and Targeting: Define how features will target different user segments. For instance, toggles can be set to activate features for users in a specific geographic location or those who meet certain usage criteria.
• Environment-Specific Configurations: Distinguish between different environments (e.g., development, staging, production) to prevent unintended impacts. Each toggle should support separate toggle configurations for each environment (i.e. on by default in development and off by default in production) to reduce risks associated with deploying new features.

4. Integration With Development Workflows

Ensure that feature toggles are seamlessly integrated into your development and deployment workflows. This includes:

• Version Control: Feature toggle configurations should be version-controlled to track changes and maintain an audit trail.
• Automated Testing: Integrate feature toggles into your automated testing processes to ensure that the feature behaves as expected in both states (on and off) under various conditions. Learn how to override flag states from within your test scripts, so you can test these different states in parallel in the same environment.
• Monitoring and Logging: Implement logging and monitoring for feature toggle usage to identify issues early and optimize performance based on real-time data.

By carefully configuring feature toggles, you can enhance your application’s flexibility and responsiveness to business needs and user feedback while maintaining control and stability of the overall system. The next section will discuss tips for integrating these toggles with your CI/CD pipelines, ensuring a smooth and efficient release process.

Integration with CI/CD Pipelines

Feature toggles are particularly effective when used with trunk-based development. By incorporating feature toggles into Continuous Integration (CI) and Continuous Deployment (CD) pipelines, teams can merge new code into the main branch more frequently and safely—often multiple times a day—without disrupting the production environment.

This integration typically involves automated scripts that manage the rules for feature toggles and the application code. When new code is committed, the CI server runs tests and, if successful, triggers the CD process. The CD pipeline then deploys this new code to a staging or production environment, where the feature toggle rules determine if the new features should be active or remain dormant. This setup allows for the continuous delivery of new features while maintaining the stability of the live application, effectively decoupling deployment from the feature release process.

Managing Feature Toggles

Effectively managing feature toggles is crucial in ensuring they serve their purpose without becoming a burden or contributing to technical debt. Proper management optimizes the application’s functionality and maintains a clean, efficient codebase.

Feature Flag Management Systems

Feature flag management systems are powerful tools for keeping your toggles organized. They provide a centralized platform for systematically creating, managing, and retiring feature toggles. A management system features:

• Centralized Control: Release toggles across different environments from a single dashboard. A management system’s centralized control makes it easier for testers to activate or deactivate features and monitor the status and impact of each toggle.
• Performance Metrics and Analytics: Advanced feature flag platforms provide analytics tools that track how different features perform during progressive delivery or A/B testing. This data is crucial for decision-making, especially when conducting experiments.
• Integration with Development Tools: Most feature flag management systems are designed to integrate with popular CI/CD pipelines, version control systems like GitHub, and project management tools. This integration ensures that toggles are linked directly to the work items or tasks you use as part of the normal development workflow. Being able to trace a feature toggle to work task to code commit with a simple click or API call is far more efficient than, reducing the overhead of managing toggles separately.
• Role-Based Access Control: Good management systems are built with security in mind. Most systems offer role-based access controls that restrict who can create, modify, or delete feature toggles. This level of permission management helps prevent unauthorized changes and maintains the integrity of the feature management process.

Avoiding Technical Debt

When left unchecked, feature toggles can accumulate and become technical debt. This happens when toggles remain in the code long after their feature has been fully rolled out and stabilized. Such remnants clutter the code, leading to confusion and errors during future development efforts. The following steps can help you prevent this form of technical debt.

• Automated Detection of Stale Flags: Scheduled audits help identify and evaluate all existing toggles in the system. Design your audits to assess a toggle’s ability to be retired. To automate this, the most important things to know are how long it has been since a toggle configuration has been changed, whether the toggle still sees traffic, and whether that traffic has all been to “on” or “off” for an extended period of time. Regular reviews ensure that toggles do not outstay their usefulness.
• Removal of Obsolete Toggles: Toggles become obsolete once a feature has been fully integrated, tested, and confirmed stable. Obsolete toggles should be marked for removal from the code base. This cleanup should be planned for and built into the feature development lifecycle. Fewer obsolete toggles mean fewer chances of unexpected code interactions or bugs.
• Lifecycle Management: Design your toggle usage with a lifecycle approach. From the moment a toggle is created, it should be on a path toward removal, unless it’s an operations toggle. This means each toggle should be associated with a work task which contains the purpose of the toggle, the code-commits that contain it, the expected conditions under which it will be removed, and any dependencies it has on other parts of the code. Make it easy for your team to find and remove obsolete toggles.

Ready to Start Using Feature Toggles?

Feature toggles are an essential tool in modern software development, where offering ongoing releases and updates is critical to staying competitive. Using feature toggles, organizations can safely and securely test or experiment with new features, release features in a targeted way, or offer users the ability to control which features they use individually. Start using feature toggles for free now.