{
  fieldname: 'file',
  originalname: 'FILE_NAME.pdf',
  encoding: '7bit',
  mimetype: 'application/pdf',
  buffer: <Buffer >,
  size: 0
}

{
  fieldname: 'file',
  originalname: 'FILE_NAME.pdf',
  encoding: '7bit',
  mimetype: 'application/pdf',
  buffer: <Buffer >,
  size: 0
}

import { Upload } from '@aws-sdk/lib-storage'
const upload = multer()
...
app.post('/upload', checkAuthentication, upload.single('file'), uploadStream)
...
export const uploadStream = async (req, res) => {
  const fileId = crypto.randomUUID()
  const parallelUploads3 = new Upload({
    client: s3,
    params: {
      Bucket: bucketName,
      Key: fileId,
      Body: file.stream
      //         ?^ stream does not exist on file object
    },
    queueSize: 1,
  })
}

import { Upload } from '@aws-sdk/lib-storage'
const upload = multer()
...
app.post('/upload', checkAuthentication, upload.single('file'), uploadStream)
...
export const uploadStream = async (req, res) => {
  const fileId = crypto.randomUUID()
  const parallelUploads3 = new Upload({
    client: s3,
    params: {
      Bucket: bucketName,
      Key: fileId,
      Body: file.stream
      //         ?^ stream does not exist on file object
    },
    queueSize: 1,
  })
}