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Reflag Node.js OpenFeature Provider

The official OpenFeature Node.js provider for Reflag feature management service.

Installation

npm install @reflag/openfeature-node-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 @reflag/node-sdk currently is 2.0.0.

npm install @openfeature/server-sdk @reflag/node-sdk

Migrating from Bucket OpenFeature SDK

If you have been using the Bucket SDKs, the following list will help you migrate to Reflag SDK:

  • Bucket* classes, and types have been renamed to Reflag* (e.g. BucketClient is now ReflagClient)
  • All environment variables that were prefixed with BUCKET_ are now prefixed with REFLAG_
  • The BUCKET_HOST environment variable and host option have been removed from ReflagClient constructor, use REFLAG_API_BASE_URL instead
  • The BUCKET_FEATURES_ENABLED and BUCKET_FEATURES_DISABLED have been renamed to REFLAG_FLAGS_ENABLED and REFLAG_FLAGS_DISABLED
  • The default configuration file has been renamed from bucketConfig.json to reflag.config.json
  • The fallbackFeatures property in client constructor and configuration files has been renamed to fallbackFlags
  • featureKey has been renamed to flagKey in all methods that accepts that argument
  • The SDKs will not emit evaluate and evaluate-config events anymore

Usage

The provider uses the Reflag Node.js SDK. The available options can be found in the Reflag Node.js SDK.

Example using the default configuration

import { ReflagNodeProvider } from "@reflag/openfeature-node-provider";
import { OpenFeature } from "@openfeature/server-sdk";

const provider = new ReflagNodeProvider({ secretKey });

await OpenFeature.setProviderAndWait(provider);

// set a value to the global context
OpenFeature.setContext({ region: "us-east-1" });

// set a value to the invocation context
// this is merged with the global context
const requestContext = {
  targetingKey: req.user.id,
  email: req.user.email,
  companyPlan: req.locals.plan,
};

const client = OpenFeature.getClient();

const enterpriseFlagEnabled = await client.getBooleanValue(
  "enterpriseFlag",
  false,
  requestContext,
);

Feature resolution methods

The Reflag OpenFeature Provider implements the OpenFeature evaluation interface for different value types. Each method handles the resolution of flags according to the OpenFeature specification.

Common behavior

All resolution methods share these behaviors:

  • Return default value with PROVIDER_NOT_READY if client is not initialized,
  • Return default value with FLAG_NOT_FOUND if flag doesn't exist,
  • Return default value with ERROR if there was a type mismatch,
  • Return evaluated value with TARGETING_MATCH on successful resolution.

Type-Specific Methods

Boolean Resolution

client.getBooleanValue("my-flag", false);

Returns the flags's enabled state. This is the most common use case for flags.

String Resolution

client.getStringValue("my-flag", "default");

Returns the flags's remote config key (also known as "variant"). Useful for multi-variate use cases.

Number Resolution

client.getNumberValue("my-flag", 0);

Not directly supported by Reflag. Use getObjectValue instead for numeric configurations.

Object Resolution

// works for any type:
client.getObjectValue("my-flag", { defaultValue: true });
client.getObjectValue("my-flag", "string-value");
client.getObjectValue("my-flag", 199);

Returns the flag's remote config payload with type validation. This is the most flexible method, allowing for complex configuration objects or simple types.

The object resolution performs runtime type checking between the default value and the flag payload to ensure type safety.

Translating Evaluation Context

Reflag uses a context object of the following shape:

/**
 * Describes the current user context, company context, and other context.
 * This is used to determine if flag targeting matches and to track events.
 **/
export type ReflagContext = {
  /**
   * The user context. If the user is set, the user ID is required.
   */
  user?: {
    id: string;
    name?: string;
    email?: string;
    avatar?: string;
    [k: string]: any;
  };

  /**
   * The company context. If the company is set, the company ID is required.
   */
  company?: { id: string; name?: string; avatar?: string; [k: string]: any };

  /**
   * The other context. This is used for any additional context that is not related to user or company.
   */
  other?: Record<string, any>;
};

To use the Reflag Node.js OpenFeature provider, you must convert your OpenFeature contexts to Reflag contexts. You can achieve this by supplying a context translation function which takes the OpenFeature context and returns a corresponding Reflag Context:

import { ReflagNodeProvider } from "@openfeature/reflag-node-provider";

const contextTranslator = (context: EvaluationContext): ReflagContext => {
  return {
    user: {
      id: context.targetingKey ?? context["userId"]?.toString(),
      name: context["name"]?.toString(),
      email: context["email"]?.toString(),
      avatar: context["avatar"]?.toString(),
      country: context["country"]?.toString(),
    },
    company: {
      id: context["companyId"]?.toString(),
      name: context["companyName"]?.toString(),
      avatar: context["companyAvatar"]?.toString(),
      plan: context["companyPlan"]?.toString(),
    },
  };
};

const provider = new ReflagNodeProvider({ secretKey, contextTranslator });

OpenFeature.setProvider(provider);

Tracking feature adoption

The Reflag OpenFeature provider supports the OpenFeature Tracking API. It's straight forward to start sending tracking events through OpenFeature.

Simply call the "track" method on the OpenFeature client:

import { ReflagNodeProvider } from "@reflag/openfeature-node-provider";
import { OpenFeature } from "@openfeature/server-sdk";

const provider = new ReflagNodeProvider({ secretKey });

await OpenFeature.setProviderAndWait(provider);

const client = OpenFeature.getClient();

// `evaluationContext` is whatever you use to evaluate features based off
const enterpriseFlagEnabled = await client.track("huddles", evaluationContext);

License

MIT License Copyright (c) 2025 Bucket ApS