AWS Lambda for image resizing with sharp

lambda-image-resizer.js

const sharp = require('sharp');
const aws = require('aws-sdk');
const s3 = new aws.S3();

const Bucket = "BucketName";
const transforms = [
  { name: 'small', size: 85 },
  { name: 'medium', size: 160 },
  { name: 'large', size: 250 },
];

exports.handler = async (event, context) => {
  const key = event.Records[0].s3.object.key;
  const sanitizedKey = key.replace(/\+/g, ' ');
  const keyWithoutExtension = sanitizedKey.replace(/.[^.]+$/, '');
  const parts = key.split('/');
  const folder = parts[0];
  const file = parts[1];

  if (key.match('-size-')) {
    return context.succeed();
  }

  try {
    const data = await s3.listObjects({ Bucket, Prefix: `${folder}/` }).promise();
    const files = data.Contents;
    const Objects = files.reduce((acc, f) => {
      if (!f.Key.match(file)) acc.push({ Key: f.Key });
      return acc;
    }, []);

    if (Objects.length) {
      await s3.deleteObjects({ Bucket, Delete: { Objects } }).promise();
    }

    const image = await s3.getObject({ Bucket, Key: sanitizedKey }).promise();

    for (const t of transforms) {
      const resizedImg = await sharp(image.Body).resize(t.size, t.size).max().toFormat('jpeg').toBuffer();
      const updated = await s3.putObject({ Bucket, Body: resizedImg, Key: `${keyWithoutExtension}-size-${t.name}.jpg` }).promise();
    }

    context.succeed();
  }
  catch(err) {
    context.fail(`Error resizing files: ${err}`);
  }
}