upload.js

import multer from 'multer';
import firebaseAdmin from 'firebase-admin';

import { default as serviceAccount } from '../../config/newapp-6a21b-firebase-adminsdk-l4qfa-aea1ab47b1.json';

export const config = {
  api: {
    bodyParser: false,
  },
}

// Helper method to wait for a middleware to execute before continuing
// And to throw an error when an error happens in a middleware
function runMiddleware(req, res, fn) {
  return new Promise((resolve, reject) => {
    fn(req, res, (result) => {
      if (result instanceof Error) {
        return reject(result)
      }

      return resolve(result)
    })
  })
}

const uploader = multer({
  storage: multer.memoryStorage(),
  limits: {
      fileSize: 5 * 1024 * 1024, // keep images size < 5 MB
  },
}).single('resumeFile');

if (!firebaseAdmin.apps.length) {
  firebaseAdmin.initializeApp({
    credential: firebaseAdmin.credential.cert(serviceAccount),
    databaseURL: 'https://newapp-6a21b.firebaseio.com',
  });
}
const storage = firebaseAdmin.storage();
async function handler(req, res) {
  await runMiddleware(req, res, uploader);
  if (!req.file) {
    res.status(400).send('No file uploaded.');
    return;
}
  try {
    const bucket = storage.bucket('gs://newapp-6a21b.appspot.com')
     // Create new blob in the bucket referencing the file
     const blob = bucket.file(`resume/${req.file.originalname}`);
     // Create writable stream and specifying file mimetype
     const blobWriter = blob.createWriteStream({
       metadata: {
         contentType: req.file.mimetype,
       },
     });

     blobWriter.on('error', console.error);

     blobWriter.on('finish', () => {
       // Assembling public URL for accessing the file via HTTP
       const publicUrl = `https://firebasestorage.googleapis.com/v0/b/${
         bucket.name
       }/o/${encodeURIComponent(blob.name)}?alt=media`;

       // Return the file name and its public URL
       res
         .status(200)
         .send({ fileName: req.file.originalname, fileLocation: publicUrl });
     });

     // When there is no more data to be consumed from the stream
     blobWriter.end(req.file.buffer);
  } catch (error) {
    console.log('error :>> ', error);
    res.status(500).json({
      message: 'An error occured, please try again',
    });
  }
}
export default handler;