Firebase Realtime Database with NestJS

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Ref. https://github.com/patharanordev/nest-firebase-rltdb

Preparation

Firebase service account

Download service account (*.json) from Firebase console, it should look like this :

{
  "type": "service_account",
  "project_id": "YOUR_PROJECT_ID",
  "private_key_id": "YOUR_PRIVATE_KEY_ID",
  "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvg.....9aSkqIJxHcom\n-----END PRIVATE KEY-----\n",
  "client_email": "firebase-adminsdk-???????@YOUR_PROJECT_ID.iam.gserviceaccount.com",
  "client_id": "YOUR_CLIENT_ID",
  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
  "token_uri": "https://oauth2.googleapis.com/token",
  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/firebase-adminsdk-???????%40YOUR_PROJECT_ID.iam.gserviceaccount.com"
}

add project_id, private_key, client_email and your Realtime database URL to your .env file.

FIREBASE_PROJECT_ID=YOUR_PROJECT_ID
FIREBASE_PRIVATE_KEY="-----BEGIN PRIVATE KEY-----\nMIIEvg.....9aSkqIJxHcom\n-----END PRIVATE KEY-----\n"
FIREBASE_CLIENT_EMAIL=firebase-adminsdk-???????@YOUR_PROJECT_ID.iam.gserviceaccount.com
FIREBASE_REALTIME_DATABASE=YOUR_REALTIME_DATABASE_URL

Accessing to Firebase

In src/main.ts, initial Firebase admin :

import { NestFactory } from '@nestjs/core'
import { AppModule } from './app.module'
import { ConfigService } from '@nestjs/config'

import * as admin from 'firebase-admin'
import { ServiceAccount } from 'firebase-admin'

async function bootstrap() {
  const app = await NestFactory.create(AppModule)
  const configService: ConfigService = app.get(ConfigService)
  const adminConfig: ServiceAccount = {
    projectId: configService.get<string>('FIREBASE_PROJECT_ID'),
    privateKey: configService.get<string>('FIREBASE_PRIVATE_KEY'),
    clientEmail: configService.get<string>('FIREBASE_CLIENT_EMAIL'),
  }

  admin.initializeApp({
    credential: admin.credential.cert(adminConfig),
    databaseURL: configService.get<string>('FIREBASE_REALTIME_DATABASE'),
  })

  app.enableCors()

  await app.listen(3000)
}
bootstrap()

and don't forget adding ConfigModule to AppModule in app.module.ts :

// ...
import { ConfigModule } from '@nestjs/config'

@Module({
  imports: [ConfigModule],
  // ...
})
export class AppModule {}

Now you can connecting to Firebase, let's create sample service/API. In this case I assume that service is payment service, I will update payment status to the Firebase Realtime database.

Implement update service

I created status service (src/status/), the service will update result to Firebase Realtime database by reference to user ID, I called id :

// Ref. src/status.controller.ts
// ...

@Controller()
export class StatusController {
  // ...

  @Post('/status/:id')
  async updateStatus(@Param() params): Promise<string> {
    return await this.statusService.updateStatus(params.id)
  }
}

In the service, just update payment status and current timestamp to specific path of our Firebase Realtime database {FIREBASE_REALTIME_DATABASE}/{ENV}/{SERVICE_NAME}/{USER_ID}.

For timestamp, don't forget set timezone in Dockerfile too :

# Set timezone
ENV TZ=Asia/Bangkok
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone

For production, please don't forget changing Firebase Realtime database child path to environment variable.
PatharaNor
Tech Writer

// Ref. src/status.service.ts

import { Injectable } from '@nestjs/common'
import * as admin from 'firebase-admin'

@Injectable()
export class StatusService {
  async updateStatus(id: string): Promise<string> {
    const rootRef = admin.database().ref('/')

    const result = new Promise<string>((resolve, reject) => {
      const timezone = new Date().getTimezoneOffset() * 60000 //offset in milliseconds
      const timestamp = new Date(Date.now() - timezone).toISOString().slice(0, -1)

      rootRef
        .child('dev')
        .child('payment')
        .child(id)
        .set(
          {
            status: 'payment-success',
            timedstamp: timestamp,
          },
          (err) => {
            if (err) {
              reject(err.message)
            } else {
              resolve('Done')
            }
          }
        )
    })

    return result
  }
}

Usage

I prepared Dockerfile.local and docker-compose.local.yml to testing on localhost, just run :

docker-compose -f docker-compose.local.yml up --build

In this case the specific Firebase Realtime database path, it is {FIREBASE_REALTIME_DATABASE}/dev/payment/t2, please refer to image below :

ENV: dev
SERVICE_NAME: payment
USER_ID: t2

example-result-in-database

To stop the service :

docker-compose -f docker-compose.local.yml down -v

Issues

In case your service cannot connect to Firebase, it shows infinite error message below :
# ...

@firebase/database: FIREBASE WARNING: {"code":"app/invalid-credential","message":"Credential implementation provided to initializeApp() via the \"credential\" property failed to fetch a valid Google OAuth2 access token with the following error: \"Error fetching access token: Error while making request: getaddrinfo ENOTFOUND accounts.google.com. Error code: ENOTFOUND\"."}
@firebase/database: FIREBASE WARNING: {"code":"app/invalid-credential","message":"Credential implementation provided to initializeApp() via the \"credential\" property failed to fetch a valid Google OAuth2 access token with the following error: \"Error fetching access token: Error while making request: getaddrinfo ENOTFOUND accounts.google.com. Error code: ENOTFOUND\"."}
@firebase/database: FIREBASE WARNING: {"code":"app/invalid-credential","message":"Credential implementation provided to initializeApp() via the \"credential\" property failed to fetch a valid Google OAuth2 access token with the following error: \"Error fetching access token: Error while making request: getaddrinfo ENOTFOUND accounts.google.com. Error code: ENOTFOUND\"."}
So client side need to set timeout if the client journey related to Firebase.
PatharaNor
Tech Writer