NestJS

The OpenFeature NestJS SDK is a package that provides a NestJS wrapper for the OpenFeature Node Server SDK.

info

We don't have a specific provider for NestJS, you have to use the GO Feature Flag node provider with the OpenFeature SDK.

We recommend you to check the OpenFeature NestJS SDK Documentation to see all the available directives and how to use them.

Install dependencies

The first things we will do is install the Open Feature SDK and the GO Feature Flag provider.

yarn

# yarn requires manual installation of the peer dependencies (see below) 
yarn add @openfeature/nestjs-sdk \
    @openfeature/server-sdk \
    @openfeature/core \
    @openfeature/go-feature-flag-provider

npm

npm i @openfeature/nestjs-sdk @openfeature/go-feature-flag-provider

Initialize your Open Feature client

To evaluate the flags you need to have an Open Feature configured in your app. This code block shows you how you can create a client that you can use in your application.

import { Module, OnModuleInit } from '@nestjs/common';
import { OpenFeatureModule } from '@openfeature/nestjs-sdk';
import { GoFeatureFlagProvider } from  '@openfeature/go-feature-flag-provider';
import { OpenFeature } from '@openfeature/server-sdk';

@Module({
  imports: [
    ...
    OpenFeatureModule.forRoot({
      contextFactory: () => ({
        targetingKey: 'nestjs-test'
      }),
    }),
  ],
  controllers: [...],
  providers: [
      goffProvider: new GoFeatureFlagProvider({
        endpoint: 'http://localhost:1031/' // DNS of your instance of relay proxy
      }),
  ],
})
export class AppModule implements OnModuleInit {
  async onModuleInit() {
    await OpenFeature.setProviderAndWait(provider);
  }
}

Evaluate your flag

To use the OpenFeature NestJS SDK in a service first inject the OpenFeatureClient into the service.
Then use a flag value by creating the EvaluationContext, and pass the flag key, default value, and EvaluationContext to one of the OpenFeature flag evaluation methods.

import { Injectable, Inject } from '@nestjs/common';
import { OpenFeatureClient, Client } from '@openfeature/nestjs-sdk';

const EVALUATION_CONTEXT = { targetingKey: '4b9e3d6e-cb2a-40fb-8834-5352c59f04c1' };

@Injectable()
export class ExampleService {
  constructor(
    @OpenFeatureClient() private ofClient: Client,
  ) {}

  async testFlag() {
    const testFlag = await this.ofClient.getBooleanValue(
      'test-flag',
      false,
      EVALUATION_CONTEXT,
    );
  }
}

Required TargetingKey

GO Feature Flag needs a targetingKey to be set on the evaluation context.
This is used to bucket the users into the correct targeting group for the feature flag evaluation.

Contribute to the provider

You can find the source of the provider in the open-feature/js-sdk-contrib repository.