Uploading files to Firebase/ Storage using Nodejs, express and multer with diskStorage as storage option

node-express-multer-diskStorage-firebase.js

const fs = require('fs/promises');
const express = require('express');
const morgan = require('morgan');
const cors = require('cors');
const createError = require('http-errors');
const bodyParser = require('body-parser');
const { initializeApp } = require('firebase/app');
const {
  getStorage,
  ref,
  uploadBytes,
  getDownloadURL,
} = require('firebase/storage');
const multer = require('multer');

const app = express();

// Firestore setup
const { API_KEY, AUTH_DOMAIN, PROJECT_ID, BUCKET, SENDER_ID, APP_ID } =
  process.env;

const firebaseConfig = {
  apiKey: API_KEY,
  authDomain: AUTH_DOMAIN,
  projectId: PROJECT_ID,
  storageBucket: BUCKET,
  messagingSenderId: SENDER_ID,
  appId: APP_ID,
};
const firebaseApp = initializeApp(firebaseConfig);
const firestore = getStorage(firebaseApp);

// Multer setup
const storage = multer.diskStorage({
  destination: (req, file, cb) => {
    cb(null, 'tmp/');
  },
  filename: (req, file, cb) => {
    cb(null, new Date().getTime() + '-' + file.originalname);
  },
});
const upload = multer({ storage });

// Middleware
app.use(morgan('dev'));
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
app.use(cors());

// Routes
app.post('/products', upload.single('image'), async (req, res, next) => {
  try {
      const file = await fs.readFile(req.file.path);
      const imageRef = ref(firestore, 'products/' + req.file.filename);
      const snapshot = await uploadBytes(imageRef, file);
      const imageURL = await getDownloadURL(snapshot.ref);
    
      // Remove file from /tmp folder after it has been uploaded       
      fs.unlink(req.file.path);
    
      res.status(200).send(imageURL);
  } catch (error) {
    return next(createError(502, error.message));
  }
});

// Non existing routes
app.use((req, res, next) => {
  const error = new createError.NotFound();
  next(error);
});
// Error handling
app.use((error, req, res, next) => {
  res
    .status(error.status || 500)
    .json({ message: error.message || 'Server error' });
});

app.listen(process.env.PORT || 3000);