NestJS Auth.js

A NestJS integration for Auth.js that provides seamless authentication with multiple providers, session management, and role-based access control using NestJS patterns.

This integration brings the power and flexibility of Auth.js to NestJS applications with full TypeScript support, framework-agnostic HTTP adapters (Express/Fastify), and NestJS-native patterns including guards, decorators, and dependency injection.

Why?

Modern web applications require robust, secure, and flexible authentication systems. While Auth.js provides excellent authentication capabilities, integrating it with NestJS applications requires careful consideration of framework patterns, dependency injection, and TypeScript integration.

However, a direct integration isn't always straightforward. Different types of applications or deployment scenarios might warrant different approaches:

• Framework Integration: Auth.js operates at the HTTP level, while NestJS uses decorators, guards, and dependency injection. A proper integration should bridge this gap by providing NestJS-native patterns for authentication and authorization while maintaining the full Auth.js ecosystem compatibility.
• HTTP Adapter Abstraction: NestJS supports multiple HTTP frameworks (Express, Fastify). Teams need a unified approach that works seamlessly with both, allowing framework switching without changing authentication code.
• Session and Request Lifecycle: Proper session handling in NestJS requires integration with the request lifecycle, guards, and decorators. Manual integration often leads to inconsistent session management or improper request handling across different routes.
• Role-Based Access Control: Many applications need fine-grained authorization beyond simple authentication. This requires seamless integration between Auth.js user data and NestJS authorization patterns.

This integration, @mridang/nestjs-auth, aims to provide the flexibility to handle such scenarios. It allows you to leverage the full Auth.js ecosystem while maintaining NestJS best practices, ultimately leading to a more effective and less burdensome authentication implementation.

Installation

Install using NPM by using the following command:

npm install @mridang/nestjs-auth @auth/core

Usage

To use this integration, add AuthJsModule to your NestJS application module. The module provides authentication infrastructure with configurable guards, middleware, and decorators.

You'll need to configure it with your Auth.js providers and options. The integration will then be available throughout your application via NestJS dependency injection.

First, add the module to your AppModule:

import { Module } from '@nestjs/common';
import { AuthJsModule } from '@mridang/nestjs-auth';
import GoogleProvider from '@auth/core/providers/google';

@Module({
  imports: [
    AuthJsModule.register({
      providers: [
        GoogleProvider({
          clientId: process.env.GOOGLE_CLIENT_ID,
          clientSecret: process.env.GOOGLE_CLIENT_SECRET,
        }),
      ],
      secret: process.env.AUTH_SECRET,
      trustHost: true,
    }),
  ],
})
export class AppModule {}

Using the Authentication System

The integration provides several decorators and guards for handling authentication:

Decorators and Guards:

• @Public(): Marks routes as publicly accessible, bypassing authentication
• @RequireRoles(): Restricts access to users with specific roles
• @AuthSession(): Injects the current Auth.js session into route handlers
• AuthJsGuard: Global guard for authentication (applied by default)
• RolesGuard: Global guard for role-based authorization

Basic Usage:

import { Controller, Get } from '@nestjs/common';
import { AuthSession, Public, RequireRoles } from '@mridang/nestjs-auth';
import type { Session } from '@auth/core/types';

@Controller('api')
export class ApiController {
  @Get('public')
  @Public() // Bypass authentication
  getPublicData() {
    return { message: 'Public endpoint' };
  }

  @Get('profile')
  // Authenticated by default (global guard)
  getProfile(@AuthSession() session: Session | null) {
    return {
      user: session?.user,
      expires: session?.expires,
    };
  }

  @Get('admin')
  @RequireRoles('admin') // Role-based access
  getAdminData(@AuthSession() session: Session | null) {
    return { adminData: true };
  }
}

Example: Advanced Configuration with Multiple Providers

This example shows how to use async registration with multiple Auth.js providers and custom session configuration:

import { Module } from '@nestjs/common';
import { ConfigModule, ConfigService } from '@nestjs/config';
import { AuthJsModule } from '@mridang/nestjs-auth';
import GoogleProvider from '@auth/core/providers/google';
import GitHubProvider from '@auth/core/providers/github';

@Module({
  imports: [
    ConfigModule.forRoot(),
    AuthJsModule.registerAsync(
      {
        imports: [ConfigModule],
        useFactory: (configService: ConfigService) => ({
          providers: [
            GoogleProvider({
              clientId: configService.get('GOOGLE_CLIENT_ID'),
              clientSecret: configService.get('GOOGLE_CLIENT_SECRET'),
            }),
            GitHubProvider({
              clientId: configService.get('GITHUB_CLIENT_ID'),
              clientSecret: configService.get('GITHUB_CLIENT_SECRET'),
            }),
          ],
          secret: configService.get('AUTH_SECRET'),
          trustHost: true,
          session: {
            strategy: 'jwt',
            maxAge: 30 * 24 * 60 * 60, // 30 days
          },
          callbacks: {
            jwt: async ({ token, user }) => {
              if (user) {
                token.roles = user.roles;
              }
              return token;
            },
            session: async ({ session, token }) => {
              session.user.roles = token.roles as string[];
              return session;
            },
          },
        }),
        inject: [ConfigService],
      },
      {
        globalGuard: true, // Require auth by default
        rolesGuard: true, // Enable role-based access
        basePath: '/auth', // Auth routes base path
      },
    ),
  ],
})
export class AppModule {}

Known Issues

• HTTP Adapter Dependencies: The integration dynamically detects Express or Fastify adapters based on the underlying NestJS HTTP adapter. Other custom HTTP adapters may require additional adapter implementations.
• Session Storage Configuration: The integration relies on Auth.js session handling mechanisms. When configuring custom session storage or database adapters, ensure they are properly configured in the Auth.js options passed to the module.
• Role-Based Authorization (RolesGuard): The roles guard expects user roles to be available in the session.user.roles array. Ensure your Auth.js callbacks (particularly jwt and session callbacks) properly populate this field from your authentication provider or database.
• Type Augmentation: The integration automatically augments Express and Fastify request types with session properties. For custom user properties beyond the default Auth.js user schema, you'll need to extend the Auth.js types in your application.

Useful links

• Auth.js: The authentication library that this integration is built upon.
• NestJS: The Node.js framework this integration is designed for.
• Auth.js Providers: Complete list of supported authentication providers.

Contributing

If you have suggestions for how this integration could be improved, or want to report a bug, open an issue - we'd love all and any contributions.

License

Apache License 2.0 © 2024 Mridang Agarwalla