What is a feature flag?
A feature flag is a software development approach that allows for the remote activation or deactivation of functionality without the need for code deployment. With feature flags, it is possible to introduce new features at runtime without additional code. By separating deployment from release, feature flags enable you to control a feature’s entire lifespan and opt for secure testing in production mode.
A feature flag can regulate access, for instance, if new features are made accessible to internal users for testing and feedback. The functionality is only visible to employees who are connected to the program using a corporate email address.
Feature flags enable you to classify risk and manage components. A/B testing, rolling out features to certain users, excluding particular groups from viewing a feature, and similar other activities are thus made possible.
There are distinct kinds of feature flags, which are divided into categories depending on their dynamism and lifespan and used for various reasons. A few of the types are:
- Short-lived: Feature flags that are meant to temporarily deploy new changes and test in production.
- Long-lived: Flags such as kill switches, remain in your system longer.
- Dynamic: Value changes are enabled at runtime.
- Static: Only real modifications to code or configuration files are permitted.
Benefits of feature flags
Fundamentally, feature flags allow for the deployment and activation of code in production while it is in an inactive form. Consequently, teams have more authority over how the final output is used. Feature flags are now essential for the speedy and secure launch of new functionalities. Here are just a few ways they may improve your software development and delivery processes:
Continuous delivery
Feature flags let teams use trunk-based development without worrying about creating persistent branches or experiencing the infamous merge nightmare. If numerous developers work on overlapping areas of the codebase, integrating complex new features or delicate refactoring work into a repository’s primary production branch might become challenging. To reduce complex code integration and deployment circumstances, feature flags can be helpful.
Release management
The most common use of feature flags is in the build or feature release process. In release management, you can give specific users early access to new features, canary releases, or beta programs. Initially targeting small groups, then scaling up over time helps you achieve the following:
- Under increasing load, observe how systems and services perform.
- Take user feedback into account and make adjustments if necessary.
- Make sure the blast radius is limited if something goes wrong.
Boost product release frequency and verify feature functionality
Using feature flags to perform “soft-rollouts” enables risk-free continuous testing in production. As a result, toggles for new functionality may be included right away as part of the anticipated release. By regularly verifying any changes on a sample of users, you can deploy features to consumers much faster and product releases that are high-quality and less buggy.
Operative efficiency
System features can be toggled on/off with feature flags to minimize the impact of incidents. You can use operational feature flags to:
- Activate circuit breakers or kill switches to prevent features from negatively impacting the user experience and triggering alerts.
- Ensure API reliability by limiting API requests.
- Switch to a lighter-on-feature version, when a page is heavily loaded.
- Ensure that new microservices and third-party tags are compatible in production.
- Aid with debugging, and change log levels as needed.
Continuous server-side experimentation
Using feature flags, you can quickly test your changes on a small group of users and track performance according to your specified KPIs. Experimenting through A/B testing enables you to discover new things.
You may verify or reject intuition by testing various feature settings with feature flags. To make sure you are introducing the optimal version of a feature that positively influences business KPIs, experimentation offers tangible data and practical measures.
Risk reduction
Using the concept of soft rollouts as a foundation, vigilant teams may use feature flags in combination with real-time monitoring and analytics as a solution to any apparent intermittent difficulties.
Challenges of feature flags
While the usage of feature flags is recommended and greatly improves the workflow of your team, there are situations when you may encounter some difficulties, such as:
Complexity
Using feature flags can grow complicated over time and as use cases expand, especially since some firms choose internal systems that might not be sophisticated enough to serve your goods.
Erratic script and collaboration
Over time, a system’s accumulation of feature flags may result in disorganized code. Your system’s functionality may be disrupted by the conditional statements that are dispersed across your code base, and the existence of various code paths makes it challenging to identify the root cause of a problem while debugging.
Technical liabilities
Flags must be cleared once they have been utilized and are no longer functional since keeping stale, inactive flags around will ultimately cause your system to accrue technical debt.
Feature flag best practices
When using feature flags, a variety of procedures must be followed. The following are some recommended practices that you should take into account and apply to make your experience using feature flags as seamless as possible:
Apply a standardized naming convention
Without a naming standard, members of your team can start referring to different flags by the same name, which could lead to confusion. As a result, there may be system disturbances if your team activates the incorrect flag.
Manage who has access to flags
Put in place logging to keep track of who made significant changes and when. This is critical for reducing reliance between the product and engineering teams and increasing efficiency because there will be more transparency when it comes to implementing modifications.
Manage each toggle in a specific way
Since there are many sorts of flags, each demands a unique way to be managed. It would be wrong to handle and implement a release toggle and kill switch in the same manner, for instance.
Maintain frequent flag cleaning
Be sure to periodically remove any no longer-used flags from your system such as the flags that are only intended to be temporary and fulfill a single function.
Conclusion
Feature flags are an effective tool in the continuous delivery toolkit and can be used in a variety of inventive ways. In general, feature flags allow teams to have more control over their codebase, deployment, and end-user experience.
