How to Dynamically Update User Segments in ConfigCat

In modern software development, feature flags are a must-have. They let teams release features gradually, run A/B tests, and control access for different user groups. But there's a common challenge: How do you keep a list of dynamic user segments (like beta testers) always up to date without manually editing the dashboard every time?

To tackle this challenge, I'll show you how to update user segments in ConfigCat dynamically, including examples of setting up and using the ConfigCat's Update Segment API, best practices for managing segment details, and tips for integrating this functionality into your development workflow.

The Challenge: Dynamic Beta User Management

Let’s consider the following scenario described by a customer:

"For a gradual rollout, we would like to have something like 'beta users,' which is a list of user IDs that I can add to the segment and use in our flags. The issue is that this list is dynamic and can change as we add new users and remove older ones. Do you have any creative way to interact with segments dynamically"?

Manually updating this list through the ConfigCat dashboard could give room for errors, be hard to manage, and also be time-consuming.

The Solution: Using the ConfigCat Update Segment API

ConfigCat's API provides a powerful way to update segments programmatically, making it efficient and ideal for managing dynamic user lists. Integrating the update segment API into your user management workflow ensures your feature flag targeting remains accurate.

Understanding Segments in ConfigCat

Segments are used to group users based on any of their properties (userId, email, role, account plan, etc.). They make it easy to control who gets access to specific features by letting you add or remove users at any time.

How the Update Segment API Works

The Update Segment API allows you to modify the comparison values used in your segments to determine which users belong to a segment. The API endpoint to update a user segment is:

PUT /v1/segments/{segmentId}

Path Parameters

• segmentId (UUID, required): This is the identifier of the segment that needs to be updated.

Request Body Schema

{
    "name": "Beta Users",
    "description": "Active participants in our beta testing program",
    "comparisonAttribute": "email",
    "comparator": "isOneOf",
    "comparisonValue": "[email protected],[email protected],[email protected]"
}

Key Fields Explained

• name: A descriptive name for your segment (Can be no longer than 255 characters).
• description: Additional information about the purpose of the segment (Can be no longer than 1000 characters).
• comparisonAttribute: This is the user attribute to use for evaluation (e.g. email, userId, role, etc.).
• comparator: The evaluation operator (in this case, "isOneOf" checks if the user attribute matches any value in a comma-separated list).

info

The choice of comparator is dependent on the logic behind your segment update usage. Other values that can be used are: isNotOneOf, contains, doesNotContain, etc. Visit the update segment section in the docs to view the valid comparators.

• comparisonValue (string): The actual values to compare against (a comma-separated list of user identifiers).

Implementing a Dynamic Beta User Management System

Here's a step-by-step guide to implementing an automated solution for managing a dynamic list of beta users:

1. Create the Initial Segment

First, create a new segment through the ConfigCat dashboard or API. Note the segmentId as you'll need it for future updates.

2. Develop an Update Script

Create a script that will:

• Retrieve the current list of beta users from your user database or system
• Format them into a comma-separated string
• Call the Update Segment API to modify the segment

3. Sample Implementation (JavaScript)

// ConfigCat API Configuration
const API_BASE_URL = "https://api.configcat.com/v1";
const API_KEY = "YOUR_API_KEY";  // Your ConfigCat Management API key
const SEGMENT_ID = "YOUR_SEGMENT_ID";  // The UUID of your beta users segment

/**
 * Retrieve current beta users from your database.
 * This is just a placeholder - implement your specific data retrieval logic.
*/
async function getCurrentBetaUsers() {
    // Replace with your actual database query
    // This could be an API call, database query, etc.
    return ["[email protected]", "[email protected]", "[email protected]"];
}

/**
 * Update the beta users segment in ConfigCat with the current list.
*/
async function updateBetaUsersSegment(userList) {
    const headers = {
        "Authorization": `bearer ${API_KEY}`,
        "Content-Type": "application/json"
 };
  
    // Format the user list as a comma-separated string
    const comparisonValue = userList.join(",");
    const payload = {
        "name": "Beta Users",
        "description": "Automatically updated list of current beta testers",
        "comparisonAttribute": "email",  // Or userId, depending on your setup
        "comparator": "isOneOf",
        "comparisonValue": comparisonValue
 };

    const url = `${API_BASE_URL}/segments/${SEGMENT_ID}`;

    try {
        const response = await fetch(url, {
            method: 'PUT',
            headers: headers,
            body: JSON.stringify(payload)
 });
    
        if (response.ok) {
 console.log(`Successfully updated beta users segment with ${userList.length} users`);
            return await response.json(); // Return the response data if needed
 } else {
 console.error(`Failed to update segment: ${response.status}`);
 console.error(await response.text());
            throw new Error(`API request failed with status ${response.status}`);
 }
 } catch (error) {
 console.error("Error updating segment:", error);
        throw error;
 }
}

/**
 * Main execution function
*/
async function main() {
    try {
        const currentBetaUsers = await getCurrentBetaUsers();
        await updateBetaUsersSegment(currentBetaUsers);
 } catch (error) {
 console.error("Failed to update beta users segment:", error);
 }
}

// Execute the update
main();

Best Practices and Considerations

1. API Rate Limiting: Be mindful of ConfigCat's API rate limits. For most use cases, it is ideal and advisable to use the API endpoint once or twice per day or when significant changes occur.

2. Segment Size Limitations: The comparison value has a character limit, so if your beta user list grows very large, consider these approaches: Having users split across multiple segments Use a different targeting approach, such as introducing a new property: "isBetaUser" attribute in user objects.

3. Error Handling: Implement proper error handling and notifications in your update script to ensure you're alerted if the segment fails to update.

Conclusion

The ConfigCat Update Segment API is a great tool for dynamically updating your user segments in ConfigCat. By automating segment updates, you can ensure your beta users always have access to the features they should be testing, without the burden of managing the list manually.

This approach highlights ConfigCat's flexibility and shows how the API can integrate with your workflows to build a more efficient, scalable feature management system. ConfigCat also provides SDKs for major programming languages and frameworks for easy integrations.

For more on feature flags, check out ConfigCat on Facebook, X, LinkedIn, and GitHub.