Feature Flagging - Implementation Design - Detailed

Introduction and Overview

Feature flagging is needed to decouple the deployment of code from the release of features. This allows teams to deploy code more frequently without having to release new features to all users at once. This can be beneficial for a number of reasons:

• Reduced risk: Feature flagging allows teams to test new features in production with a small subset of users before releasing them to all users. This can help to reduce the risk of deploying new features that have bugs or other problems.
• Faster innovation: Feature flagging allows teams to release new features more quickly without having to wait for the entire development cycle to be completed. This can help teams to stay ahead of the competition and meet the needs of their users more quickly.
• Improved user experience: Feature flagging allows teams to target new features to specific groups of users. This can help to improve the user experience by ensuring that users only see features that are relevant to them.

Scope

Implementation: This section should describe the implementation of the feature flagging solution, including the following:

• The design patterns and architectures that will be used.
• The testing strategy that will be used.

Configuration: This section should describe how the feature flagging solution will be configured, including the following:

• How feature flags will be created and managed.
• How feature flags will be rolled out and rolled back.

Security: describe the security measures that will be implemented in the feature flagging solution:

• Authorization: How will users be authorized to access and manage feature flags?
• Authentication: How will users be authenticated when accessing the feature flagging solution?
• Auditing: How will the usage of the feature flagging solution be audited.

Implementation

Design pattern

Feature Toggles: Feature toggles are the simplest way to implement feature flagging. They involve wrapping code that implements a feature with a conditional statement that checks the state of the feature flag. If the feature flag is enabled, the code is executed. If the feature flag is disabled, the code is skipped.

Testing strategy

Unit Tests

Unit tests should be written to test the functionality of the feature flagging library or SDK. These tests should cover the following:

• The ability to create, update, and delete feature flags.
• The ability to target feature flags to specific users and environments.
• The ability to roll out and roll back feature flags.
• The ability to monitor feature flags.

Integration Tests

Integration tests should be written to test the interaction of the feature flagging library or SDK with other systems, such as your application code. These tests should cover the following:

• The ability to deploy and configure the feature flagging solution.
• The ability to use the feature flagging solution to control the behavior of your application.
• The ability to monitor the usage of the feature flagging solution.

System Tests

System tests should be written to test the end-to-end functionality of the feature flagging solution. These tests should cover the following:

• The ability to create and manage feature flags.
• The ability to target feature flags to specific users and environments.
• The ability to roll out and roll back feature flags.
• The ability to monitor feature flags.
• The impact of feature flags on the behavior of your application.

Configuration

Projects:

• Projects represent the different products or applications that your team is developing.
• Each project has a unique identifier.

Environments:

• Environments represent the different stages of your development lifecycle, such as development, staging, and production.
• Each environment has a unique token.

Features:

• Features represent the different functionalities that your team is developing or has already developed.
• Each feature has a unique identifier.

Usage:

• Developers need to create a feature flag for each new feature that they are developing.
• When creating a feature flag, developers need to specify the following:
• The name of the feature
• The description of the feature
• The environment(s) where the feature will be available
• The default state of the feature (enabled/disabled)
• Once a feature flag is created, developers can start using it in their code.
• To use a feature flag, developers need to check the state of the flag before executing the code that implements the feature.
• If the feature flag is enabled, the code will be executed.
• If the feature flag is disabled, the code will be skipped.

Feature Flag Rollout and Rollback

Feature flags can be rolled out and rolled back gradually or immediately.

When rolling out a feature flag gradually, the following steps are taken:

• The feature flag is enabled for a small subset of users or environments.
• The performance of the feature flag is monitored.
• If the feature flag is working as expected, it is enabled for a larger subset of users or environments.
• This process continues until the feature flag is enabled for all users or environments.

When rolling back a feature flag, the reverse process is followed.

Security

Authentication and Authorization

Use a strong authentication mechanism, such as OAuth2 or SAML, to authenticate users. Once users are authenticated, the feature flagging solution should use an authorization mechanism to control which users have access to which feature flags.

Audit Logging

Log all activity, including feature flag creation, modification, and deletion. Audit logs should be stored securely and reviewed regularly for suspicious activity.

Additional Security Considerations

Least privilege: Users should only be granted access to the feature flags that they need to perform their job duties.

Segregation of duties: Multiple users should be required to approve changes to critical feature flags.

Change management: A change management process should be in place to control changes to the feature flagging solution.

Backups: Regular backups of the feature flagging solution should be made and stored securely.