How to save multiple versions of an image on Google cloud storage using cloud functions

index.js

const { Storage } = require('@google-cloud/storage');
const sharp = require('sharp');

const variations = [
  { prefix: 'thumb', width: 120 },
  { prefix: 'mini', width: 480 },
  { prefix: 'med', width: 1024 }
];

/**
 * Triggered from a change to a Cloud Storage bucket.
 *
 * @param {!Object} event Event payload.
 * @param {!Object} context Metadata for the event.
 */
exports.helloGCS = async (event, context) => {
  // this prevents the new created image versions from running the function and creating an endless loop 
  // you can also use different bucket, folder hierarchies or any other idea to better handle this
  const shouldIgnore = variations.some(variation => `${event.name}`.includes(`${variation.prefix}-`));
  if (shouldIgnore) {
    console.log('Ignoring image...')
    return null;
  }

  // console.log(`Processing file: ${event.name}`);
  // console.log(`  Event: ${context.eventId}`);
  // console.log(`  Event Type: ${context.eventType}`);
  // console.log(`  Bucket: ${event.bucket}`);
  // console.log(`  File: ${event.name}`);
  // console.log(`  Metageneration: ${event.metageneration}`);
  // console.log(`  Created: ${event.timeCreated}`);
  // console.log(`  Updated: ${event.updated}`);

  const storage = new Storage();
  const bucket = storage.bucket(event.bucket);

  const generateImageVariation = (variation) => new Promise((resolve, reject) => {
    console.log('Sharping...');
    const transformer = sharp()
      .resize({ width: variation.width, fit:"contain", })
      .flatten({ background: { r: 255, g: 255, b: 255 } })
      .withMetadata()
      .jpeg();

    console.log('Reading original...');
    const originalBuketFile = bucket.file(event.name);
    const remoteReadStream = originalBuketFile.createReadStream();

    const nameWithoutOriginalPrefix = `${event.name}`.replace('original-', '');
    
    const newFile = bucket.file(`${variation.prefix}-${nameWithoutOriginalPrefix}`);
    const remoteWriteStream = newFile.createWriteStream({
      contentType: 'image/jpeg',
      resumable: false,
      public: true
    });

    remoteWriteStream.on('error', () => {
      console.error(`Unable to upload image, something went wrong`);
    }).on('finish', async (resp) => {
      console.log('terminou!');
      console.log(resp);
    })

    console.log('Pipe started...');
    remoteReadStream.pipe(transformer).pipe(remoteWriteStream);
  });

  const promises = variations.map(variation => generateImageVariation(variation));
  await Promise.all(promises);
};

package.json

{
  "name": "sample-cloud-storage",
  "version": "0.0.1",
  "dependencies": {
    "@google-cloud/storage": "^5.1.2",
    "sharp": "0.27.2"
  }
}