#

NestJS Passport Strategy for Firebase Auth using Firebase Admin SDK

Installation

Install peer dependencies

``bash
npm install passport passport-jwt
npm install --save-dev @types/passport-jwt
`

Install @nestjs/passport for authentication

`bash
npm install @nestjs/passport
`

Install strategy

`bash
npm install @tfarras/nestjs-firebase-auth
`

Important

To work with Firebase Auth you need to configure and initialize your firebase app. For this purpose you can use my module for firebase-admin.

Create strategy

`typescript
import { Injectable } from "@nestjs/common";
import { PassportStrategy } from "@nestjs/passport";
import { ExtractJwt } from 'passport-jwt';
import { FirebaseAuthStrategy } from '@tfarras/nestjs-firebase-auth';

@Injectable()
export class FirebaseStrategy extends PassportStrategy(FirebaseAuthStrategy, 'firebase') {
public constructor() {
super({
extractor: ExtractJwt.fromAuthHeaderAsBearerToken(),
});
}
}
`

Note: You should provide an extractor. More information about passport-jwt extractors you can find here: http://www.passportjs.org/packages/passport-jwt/#included-extractors

Create AuthModule and provide created strategy

`typescript
import { Module } from "@nestjs/common";
import { PassportModule } from "@nestjs/passport";
import { FirebaseStrategy } from "./firebase.strategy";

@Module({
imports: [PassportModule],
providers: [FirebaseStrategy],
exports: [FirebaseStrategy],
controllers: [],
})
export class AuthModule { }
`

Import AuthModule into AppModule

`typescript
import { FirebaseAdminCoreModule } from '@tfarras/nestjs-firebase-admin';
import { Module } from '@nestjs/common';
import { ConfigModule, ConfigService } from 'nestjs-config';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { AuthModule } from './auth/auth.module';
import * as path from 'path';

@Module({
imports: [
ConfigModule.load(path.resolve(__dirname, 'config', '*', '!(.d).{ts,js}')),
FirebaseAdminCoreModule.forRootAsync({
useFactory: (config: ConfigService) => config.get('firebase'),
inject: [ConfigService],
}),
AuthModule,
],
controllers: [AppController],
providers: [AppService],
})
export class AppModule { }

`

Protect your routes

`typescript
import { Controller, Get, Inject, UseGuards } from '@nestjs/common';
import { AuthGuard } from '@nestjs/passport';
import { FirebaseAdminSDK, FIREBASE_ADMIN_INJECT } from '@tfarras/nestjs-firebase-admin';
import { AppService } from './app.service';

@Controller()
export class AppController {
constructor(
private readonly appService: AppService,
@Inject(FIREBASE_ADMIN_INJECT) private readonly fireSDK: FirebaseAdminSDK,
) { }

@Get()
@UseGuards(AuthGuard('firebase'))
getHello() {
return this.fireSDK.auth().listUsers();
}
}

`

Custom second validation

In cases when you want to validate also if user exists in your database, or anything else after successfull Firebase validation you can define custom validate method in your strategy.

Example

`typescript
import { Injectable } from "@nestjs/common";
import { PassportStrategy } from "@nestjs/passport";
import { FirebaseAuthStrategy, FirebaseUser } from '@tfarras/nestjs-firebase-auth';
import { ExtractJwt } from 'passport-jwt';

@Injectable()
export class FirebaseStrategy extends PassportStrategy(FirebaseAuthStrategy, 'firebase') {
public constructor() {
super({
extractor: ExtractJwt.fromAuthHeaderAsBearerToken(),
});
}

async validate(payload: FirebaseUser): Promise {
// Do here whatever you want and return your user
return payload;
}
}
``