Description

Nest Lib To Communicate With Unleash Feature Toggle.

Installation

$ npm install @josemarinho/unleash

Running the app

Once the installation process is complete, we can import the UnleashModule into the root AppModule.

import { Module } from '@nestjs/common';
import { UnleashModule } from '@josemarinho/unleash';

@Module({
  imports: [
    UnleashModule.forRoot({
      appName: 'app-name',
      url: 'https://unleash-api-url.com',
      apiKey: 'your-api-key',
      strategies: [new ActiveForUserWithEmailStrategy()], // Your custom strategy
      bootstrap: {
        data: [
          {
            name: 'feature-x',
            enabled: true,
            strategies: [],
          },
        ],
        disableBootstrapOverride: true,
      },
      global: false, // default is true
    }),
  ],
})
export class AppModule {}

Custom Strategies

You can define and use custom strategies by extending the Strategy class from unleash-client. Example from Docs Unleash Client - https://docs.getunleash.io/reference/sdks/node#custom-strategies

import { initialize, Strategy } from 'unleash-client';
class ActiveForUserWithEmailStrategy extends Strategy {
  constructor() {
    super('ActiveForUserWithEmail');
  }

  isEnabled(parameters, context) {
    return parameters.emails.indexOf(context.email) !== -1;
  }
}

Utilization

To retrieve feature toggles from Unleash, simply inject the UnleashService into your service or controller and use the available methods.

✅ Checking if a feature is enabled

import { Injectable } from '@nestjs/common';
import { UnleashService } from '@josemarinho/unleash';

@Injectable()
export class AppService {
  constructor(private readonly unleash: UnleashService) {}

  isFeatureEnabled(toggleName: string): boolean {
    return this.unleash.isEnabled(toggleName);
  }
}

🔍 Accessing the Unleash client directly (optional)

If you need to access advanced methods like getVariant, you can retrieve the internal Unleash client instance:

getFeatureVariant(toggleName: string) {
  const client = this.unleash.getClient();
  return client.getVariant(toggleName);
}

The UnleashService also handles cleanup automatically on application shutdown to avoid memory leaks.

After your app it's ready to running.