Initialize the Firebase Admin with Next.js

The Firebase Admin package is a way to use Firebase on NodeJS, thus allowing us to write backend code with the various Firebase packages such as Auth, Firestore, Storage, and so on.

To use Firebase with a Next.js API function, we have to initialize the Firebase Admin. Let's see how it's done:

Firebase configuration

First, we have to store and retrieve the Firebase configuration for our project.

To do so, we can use the Next.js environment variables by creating a .env file in the root folder, and making sure to fill the values below correctly:

NEXT_PUBLIC_FIREBASE_PROJECT_ID=
NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET=
FIREBASE_PRIVATE_KEY=
FIREBASE_CLIENT_EMAIL=

Once it's done, we can create a function that accepts the following interface and returns the Firebase admin app:

interface FirebaseAdminAppParams {
  projectId: string;
  clientEmail: string;
  storageBucket: string;
  privateKey: string;
}

The snippet below is everything you need to create an admin app using Firebase:

import admin from 'firebase-admin';
function formatFirebasePrivateKey(key: string) {
  return key.replace(/\\n/g, '\n');
}
export function createFirebaseAdminApp(params: FirebaseAdminAppParams) {
  const privateKey = formatFirebasePrivateKey(params.privateKey);
  
  // if already created, return the same instance
  if (admin.apps.length > 0) {
    return admin.app();
  }
  // create certificate
  const cert = admin.credential.cert({
    projectId: params.projectId,
    clientEmail: params.clientEmail,
    privateKey,
  });
  // initialize admin app
  return admin.initializeApp({
    credential: cert,
    projectId: params.projectId,
    storageBucket: params.storageBucket,
  });
}

Let's assume you created a Next.js API function and want to create a Firebase admin app to be able to use Firestore, you can do the following:

import { createFirebaseAdminApp } from './initialize-firebase-admin-app';
import { getFirestore } from 'firebase-admin/firestore';
async function initializeAdmin() {
  const params = {
    projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID,
    clientEmail: process.env.FIREBASE_CLIENT_EMAIL,
    storageBucket: process.env.NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET,
    privateKey: process.env.FIREBASE_PRIVATE_KEY
  };
  return createFirebaseAdminApp(params);
}
export default function getTeams(
  req: NextApiRequest,
  res: NextApiResponse,
) {
  // initialize admin
  await initializeAdmin();
  // now we can use the Firebase packages!
  const firestore = getFirestore();
  const { docs, size } = await firestore.collection('teams').get();
  const teams = docs.map(doc => doc.data())
  return res.send(teams);
}

The Firebase Admin package is a way to use Firebase on NodeJS, thus allowing us to write backend code with the various Firebase packages such as Auth, Firestore, Storage, and so on.

To use Firebase with a Next.js API function, we have to initialize the Firebase Admin. Let's see how it's done:

Firebase configuration

First, we have to store and retrieve the Firebase configuration for our project.

To do so, we can use the Next.js environment variables by creating a .env file in the root folder, and making sure to fill the values below correctly:

NEXT_PUBLIC_FIREBASE_PROJECT_ID=
NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET=
FIREBASE_PRIVATE_KEY=
FIREBASE_CLIENT_EMAIL=

Once it's done, we can create a function that accepts the following interface and returns the Firebase admin app:

interface FirebaseAdminAppParams {
  projectId: string;
  clientEmail: string;
  storageBucket: string;
  privateKey: string;
}

The snippet below is everything you need to create an admin app using Firebase:

import admin from 'firebase-admin';
function formatFirebasePrivateKey(key: string) {
  return key.replace(/\\n/g, '\n');
}
export function createFirebaseAdminApp(params: FirebaseAdminAppParams) {
  const privateKey = formatFirebasePrivateKey(params.privateKey);
  
  // if already created, return the same instance
  if (admin.apps.length > 0) {
    return admin.app();
  }
  // create certificate
  const cert = admin.credential.cert({
    projectId: params.projectId,
    clientEmail: params.clientEmail,
    privateKey,
  });
  // initialize admin app
  return admin.initializeApp({
    credential: cert,
    projectId: params.projectId,
    storageBucket: params.storageBucket,
  });
}

Let's assume you created a Next.js API function and want to create a Firebase admin app to be able to use Firestore, you can do the following:

import { createFirebaseAdminApp } from './initialize-firebase-admin-app';
import { getFirestore } from 'firebase-admin/firestore';
async function initializeAdmin() {
  const params = {
    projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID,
    clientEmail: process.env.FIREBASE_CLIENT_EMAIL,
    storageBucket: process.env.NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET,
    privateKey: process.env.FIREBASE_PRIVATE_KEY
  };
  return createFirebaseAdminApp(params);
}
export default function getTeams(
  req: NextApiRequest,
  res: NextApiResponse,
) {
  // initialize admin
  await initializeAdmin();
  // now we can use the Firebase packages!
  const firestore = getFirestore();
  const { docs, size } = await firestore.collection('teams').get();
  const teams = docs.map(doc => doc.data())
  return res.send(teams);
}

Initialize the Firebase Admin with Next.js

Learn how to use Firebase on the server with Next.js

Firebase configuration

Some other posts you might like...

Initialize the Firebase Admin with Next.js

Learn how to use Firebase on the server with Next.js

Firebase configuration

Some other posts you might like...