NestJS – Authentication

NestJS

Authentication

Implementing authentication in a NestJS application using Passport and JWT.

Install Dependencies: Install Passport, JWT, and their NestJS integrations.

📄terminal
bash

npm install @nestjs/passport passport @nestjs/jwt passport-jwt
npm install -D @types/passport-jwt

Auth Service: Generate a JWT token upon successful user validation or login.

📄src/auth/auth.service.ts
typescript

import { Injectable } from '@nestjs/common';
import { JwtService } from '@nestjs/jwt';

@Injectable()
export class AuthService {
  constructor(private jwtService: JwtService) {}

  async login(user: any) {
    const payload = { username: user.username, sub: user.userId };
    return {
      access_token: this.jwtService.sign(payload),
    };
  }
}

JWT Strategy: Define a Passport strategy to extract and validate the JWT from incoming requests.

📄src/auth/jwt.strategy.ts
typescript

import { ExtractJwt, Strategy } from 'passport-jwt';
import { PassportStrategy } from '@nestjs/passport';
import { Injectable } from '@nestjs/common';

@Injectable()
export class JwtStrategy extends PassportStrategy(Strategy) {
  constructor() {
    super({
      jwtFromRequest: ExtractJwt.fromAuthHeaderAsBearerToken(),
      ignoreExpiration: false,
      secretOrKey: 'YOUR_SECRET_KEY', // Should be environment variable
    });
  }

  async validate(payload: any) {
    return { userId: payload.sub, username: payload.username };
  }
}