ConfigCat Provider

This is an OpenFeature provider implementation for using ConfigCat, a managed feature flag service in Node.js applications.

Installation

$ npm install @openfeature/config-cat-provider

Required peer dependencies

The OpenFeature SDK is required as peer dependency.

The minimum required version of @openfeature/server-sdk currently is 1.13.5.

The minimum required version of configcat-node currently is 11.3.1.

$ npm install @openfeature/server-sdk configcat-node

Usage

The ConfigCat provider uses the ConfigCat Node.js SDK.

It can be created by passing the ConfigCat SDK options to ConfigCatProvider.create.

The available options can be found in the ConfigCat Node.js SDK.

Example using the default configuration

import { OpenFeature } from "@openfeature/server-sdk";
import { ConfigCatProvider } from '@openfeature/config-cat-provider';

// Create and set the provider.
const provider = ConfigCatProvider.create('<sdk_key>');
await OpenFeature.setProviderAndWait(provider);

// Obtain a client instance and evaluate feature flags.
const client = OpenFeature.getClient();

const value = await client.getBooleanValue('isAwesomeFeatureEnabled', false);
console.log(`isAwesomeFeatureEnabled: ${value}`);

// On application shutdown, clean up the OpenFeature provider and the underlying ConfigCat client.
await OpenFeature.clearProviders();

Example using a different polling mode and custom configuration

import { OpenFeature } from "@openfeature/server-sdk";
import { ConfigCatProvider } from '@openfeature/config-cat-provider';
import { createConsoleLogger, LogLevel, PollingMode } from 'configcat-node';

// Create and set the provider.
const provider = ConfigCatProvider.create('<sdk_key>', PollingMode.LazyLoad, {
  logger: createConsoleLogger(LogLevel.Info),
  setupHooks: (hooks) => hooks.on('clientReady', () => console.log('Client is ready!')),
});
await OpenFeature.setProviderAndWait(provider);

// ...

Evaluation Context

The OpenFeature Evaluation Context is mapped to the ConfigCat User Object.

The ConfigCat User Object has three predefined attributes, and allows for additional attributes. The following shows how the attributes are mapped:

| OpenFeature EvaluationContext Field | ConfigCat User Field | Required | |-------------------------------------|----------------------|----------| | targetingKey | identifier | yes | | email | email | no | | country | country | no | | Any Other | custom | no |

The custom types are mapped the following way:

| OpenFeature EvaluationContext Field Type | ConfigCat User Field Type | |-----------------------------------------------|---------------------------| | string | string | | number | number | | boolean | string | | Array | Array | | Array | Array | | object | string |

The following example shows the conversion between an OpenFeature Evaluation Context and the corresponding ConfigCat User:

OpenFeature

{
  "targetingKey": "test",
  "email": "email",
  "country": "country",
  "customString": "customString",
  "customNumber": 1,
  "customBoolean": true,
  "customObject": {
    "prop1": "1",
    "prop2": 2
  },
  "customStringArray": ["one", "two"],
  "customArray": [
    1,
    "2",
    false
  ]
}

ConfigCat

{
  "identifier": "test",
  "email": "email",
  "country": "country",
  "custom": {
    "customString": "customString",
    "customBoolean": "true",
    "customNumber": 1,
    "customObject": "{\"prop1\":\"1\",\"prop2\":2}",
    "customStringArray": ["one", "two"],
    "customArray": "[1,\"2\",false]"
  }
}

Events

The ConfigCat provider emits the following OpenFeature events:

• PROVIDER_READY
• PROVIDER_ERROR
• PROVIDER_CONFIGURATION_CHANGED

Building

Run nx package providers-config-cat to build the library.

Running unit tests

Run nx test providers-config-cat to execute the unit tests via Jest.