10 Best Practices When Using Feature Flags

Feature flags are a powerful tool for software development teams to control the release of new features. By using feature flags, teams can easily turn features on or off in real time. This allows for the quick and safe release of new functionality to users. 

In this post, we'll explore what feature flags are. We'll also cover best practices for using them and discuss common challenges and questions surrounding their use. 

What are Feature Flags?

Feature flags, also known as feature toggle or feature switch, are a software development technique. They allow developers to enable or disable certain features or functionality in their application without deploying new code. This allows for more flexible and efficient software development. Using feature flags, teams can quickly and easily test and roll out new features. They can also manage these features without impacting the stability and reliability of the application. 

Feature flags provide a number of benefits, including the ability to: 

• test new features with a small group of users before rolling them out to the entire user base;
• roll out new features gradually, rather than all at once;
• quickly disable or roll back features that are causing problems or are not performing as expected; and
• customize user experience for different groups of users or for specific regions or markets.

Best Practices When Using Feature Flags

To fully realize the benefits of feature flags, it's important to follow best practices when using them. 

1. Clean up unused feature flags

You should regularly remove temporary feature flags, such as release flags and experiment flags, when they are no longer needed. This helps prevent the accumulation of technical debt in the code. It also keeps the feature flag management system organized and easy to understand. Each flag should have a specific, independent purpose, and the code should be modular enough to allow different features to be turned on in any combination. 

However, if multiple flags are required or may conflict with each other, using flags can become confusing and may have a negative impact on user experience. To avoid these problems, you must carefully plan and manage the use of feature flags. 

2. Use a feature flag management platform

It's important to choose a feature flag management system that's easy to understand and use. These characteristics are essential whether it's a specialized tool, a config file, or a database table. When introducing feature flags to a team, take the time to carefully consider the best system for your needs. That way, the solution you pick can be used long term. 

A few popular feature flag management platforms to consider are Harness and LaunchDarkly. 

3. Establish naming conventions

Make your feature flags easy to understand and use by establishing a naming convention. Good, descriptive naming conventions and clear documentation can help ensure that all software engineers understand the purpose and use of each flag. 

When creating a naming convention, consider including a prefix with the project or team name, indicating whether the flag is temporary or permanent, and including a creation date. It may also be helpful to include the word "flag" in the name if using a homegrown solution, as this can clarify the purpose of the code. 

In general, it's a good idea to follow a style guide for code that includes conventions for things like camelCase and indentation, as this can make it easier to read and understand the code. By establishing clear naming conventions and style guidelines for feature flags, you can improve the maintainability and readability of your codebase. 

4. Use feature flags for small test releases

Big, new feature releases can be stressful and risky, as they can potentially impact the stability and reliability of the application. However, you can reduce this risk by using feature flags to expose your new feature to a small audience first, monitor the effects, and roll back if necessary. 

One of the key benefits of feature flags is the ability to perform canary releases, or the gradual rollout of a new feature to a small group of users before making it available to the entire user base. This allows you to test the functionality of the new feature and gather feedback from a small group of users before exposing it to the entire user base. 

5. Avoid dependencies between flags

Ensure that each feature flag serves a specific, independent purpose. When multiple flags are required for a single release or the state of the flag conflicts with another flag, it can lead to confusion and make it difficult to maintain the code. This can also have a negative impact on user experience. To avoid these issues, you must carefully plan and manage the use of feature flags, ensuring that they're used effectively and efficiently. 

6. Use targeted feature flags

Use feature flags to customize the user experience. Feature flags can be used to customize user experience for different groups of users or for specific regions or markets. By using targeted feature flags, developers can enable or disable features for specific users or groups based on various criteria such as location, language, or user role. 

One popular use of feature flags is to manage styling, themes, and personalized content. For example, a feature flag could be used to enable or disable dark mode for a website or app. This allows developers to test the new feature with a subset of users before rolling it out to the entire user base. 

7. Use feature flags to enable feature branches

Feature branches allow developers to work on new features in a separate branch of the codebase without impacting the stability and reliability of the main branch. This can be useful for developing and testing new features without disrupting the main development process. 

8. Track changes with audit logs

An audit log can be a useful tool for tracking and managing changes to feature flags. This log can provide a record of all changes made to each flag, including the identity of the person making the change and the date and time of the change. 

An audit log can help ensure transparency and visibility in the implementation of feature flag changes. Changes to feature flags can be particularly important in regulated industries such as finance and healthcare. By restricting access to the audit log to a limited number of authorized individuals, it's also possible to enhance the security of the process and protect sensitive flags from unauthorized changes. 

9. Control access based on policies

You may want to control access to feature flags based on policies. One of the benefits of feature flags is that they can be accessed by nontechnical team members, such as the product team, who can use them to assist with A/B testing. Another way to limit access is to allow only administrators to toggle a feature flag in a production-related environment. 

However, it's important to carefully control access to feature flags and to track changes made to them. This can involve locking changes in the production environment or maintaining a log of who's modified which flags. By taking these precautions, you can ensure that feature flags are used effectively and that changes are made by authorized personnel. 

10. Plan ahead for feature flags

Proper planning is key to the successful implementation of feature flags. Rather than treating feature flags as an afterthought, it's important to consider them during the design process. This will help you determine whether a flag should be temporary or permanent. You'll then be able to plan accordingly for things like naming conventions, configuration settings, review and removal processes, and access control and safety checks. By planning carefully for all flags upfront, you can increase the chances of success and ensure that your feature flags are implemented effectively. 

Challenges of Using Feature Flags

Feature flags can be a useful tool in software development, but they also come with their own set of challenges. Some common challenges of using feature flags include: 

• Technical debt: Using feature flags can lead to technical debt if the flags are not maintained and updated over time. This can result in increased maintenance costs and may require dedicated resources to address.
• Feature creep: Feature flags can also lead to feature creep, where more and more features are added over time without a clear plan or goal. This can result in a cluttered and confusing user experience.
• Complexity: Managing multiple feature flags can be complex, especially as the number of flags increases. Difficulty in keeping track of enabled and disabled flags can lead to potential issues with code changes and deployments.
• Overuse: It can be tempting to use feature flags as a catch-all solution, but this can lead to code complexity and maintenance issues. It's important to carefully consider whether a feature flag is the appropriate solution for a given situation, rather than relying on them as a default.
• Lack of documentation: If a feature flag management solution does not track data such as the owner and purpose of a specific flag, it can be challenging to identify and document this information. When employees change or time passes, teams may need to rediscover the original purpose of the flag in order to determine whether it is still needed or risk leaving it in the code without understanding its purpose. This can lead to confusion and the potential for unintended consequences.

^{Frequently Asked Questions (FAQs)}

When should you use feature flags?

Use feature flags when you want to release new features to a subset of users or when you need to quickly turn off a feature that's causing issues. They can also be useful for A/B testing or for gradually rolling out features. 

Where do you store feature flags?

Your team and development process will determine where you store feature flags, which can include configuration files, databases, or a feature flag platform. 

Should feature flags be removed?

Once you've tested a feature and it's ready for widespread release, it's generally a good idea to remove the feature flag and clean up any related code. This can help to reduce code complexity and improve maintainability. 

Conclusion

Overall, feature flags are a useful tool for modern software development teams to control the release of new features. By following best practices and carefully considering the challenges surrounding their use, teams can effectively leverage feature flags to enable more agile and responsive development, as well as to better control the user experience. 

Now you've learned about feature flags and best practices for using them to control the release of new features in software development. You also got answers to common questions and discovered how to effectively leverage feature flags to improve your team's workflow. Check out the complete guide to automated software environments by Release to help speed up your workflow and get your apps and projects running smoothly. 

This post was written by Israel Oyetunji. Israel is a frontend developer with a knack for creating engaging UI and interactive experiences. He has proven experience developing consumer-focused websites using HTML, CSS, JavaScript, React JS, SASS, and relevant technologies. He loves writing about tech and creating how-to tutorials for developers.