firebase.js

import firebase from "firebase";

const firebaseConfig = {
  apiKey: process.env.NEXT_PUBLIC_FIREBASE_API_KEY,
  authDomain: process.env.NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN,
  projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID,
  storageBucket: process.env.NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET,
  messagingSenderId: process.env.NEXT_PUBLIC_MESSAGING_SENDER_ID,
  appId: process.env.NEXT_PUBLIC_FIREBASE_APP_ID,
  measurementId: process.env.NEXT_PUBLIC_FIREBASE_MEASUREMENT_ID,
};

const app = !firebase.apps.length
  ? firebase.initializeApp(firebaseConfig)
  : firebase.app();

const db = app.firestore();
const auth = app.auth();
const rtdb = firebase.database();

const googleProvider = new firebase.auth.GoogleAuthProvider();
const githubProvider = new firebase.auth.GithubAuthProvider();

export { db, rtdb, auth, googleProvider, githubProvider };