Features Component

A well-known component that integrates with Unleash to provide feature flag management. It enables runtime feature toggling and configuration through a simple interface.

Quick Start

1. Install the package:

npm install @well-known-components/features-component

2. Set up environment variables:

FF_URL=https://your-unleash-instance-url
SERVER_URL=https://your-api-url

3. Create and use the component:

import { createFeaturesComponent } from '@well-known-components/features-component'

// Initialize the component
const features = await createFeaturesComponent(
  {
    config,    // WKC configuration component
    logs,      // WKC logger component
    fetch,     // WKC fetch component
  },
  await config.requireString('SERVER_URL')
)

// Check if a feature is enabled
const isEnabled = await features.getIsFeatureEnabled(
  'APPLICATION_NAME',
  'FEATURE_NAME'
)

Configuration

Required Environment Variables

Variable	Description
FF_URL	URL of your Unleash instance
SERVER_URL	Your API URL (used as referrer for Unleash's applicationHostname strategy)

Component Dependencies

The features component requires three well-known components:

• config: For accessing environment variables
• logs: For logging and debugging
• fetch: For making HTTP requests to Unleash

Usage Examples

Basic Feature Check

const isEnabled = await features.getIsFeatureEnabled(
  'MY_APP',
  'DARK_MODE'
)

if (isEnabled) {
  // Enable dark mode
}

Integration with Other Components

export const validateFeature = async (components: AppComponents, data: any) => {
  const { features, logs } = components

  const isFeatureEnabled = await features.getIsFeatureEnabled(
    'MY_APP',
    'NEW_VALIDATION'
  )

  if (isFeatureEnabled) {
    logs.log('Using new validation')
    return newValidation(data)
  }

  return legacyValidation(data)
}

API Reference

createFeaturesComponent(options, serverUrl)

Creates a new instance of the features component.

Parameters:

• options: Configuration object containing:
  • config: Configuration component instance
  • logs: Logger component instance
  • fetch: Fetch implementation for making HTTP requests
• serverUrl: URL used as referrer for Unleash's applicationHostname strategy

Returns: Promise

FeaturesComponent Methods

getIsFeatureEnabled(applicationName, featureName)

Checks if a feature is enabled in Unleash.

Parameters:

• applicationName: Your application name
• featureName: Feature flag name

Returns: Promise

Note: The actual feature flag in Unleash will be named: FF_${applicationName}_${featureName}

Feature Flag Naming Convention

Feature flags in Unleash follow this naming pattern:

FF_<APPLICATION_NAME>_<FEATURE_NAME>

For example:

• FF_MY_APP_DARK_MODE
• FF_MY_APP_NEW_VALIDATION

Contributing

Please read our contributing guidelines and code of conduct before submitting pull requests or issues.

License

This project is licensed under the Apache 2.0 License - see the LICENSE file for details.