title: Transform images into thumbnails before uploading to S3 in nodejs
body: <p>I have been trying multer-s3 for many hours, But i'm failing in creating thumbnails. Can anyone please tell me how to run it?</p>
  
  <p>Following is my code:</p>
  
  <pre><code>var upload = multer({
      storage: multerS3({
          s3: s3,
          bucket: 'test',
          // shouldTransform: function (req, file, cb) {
          //     cb(null, /^image/i.test(file.mimetype))
          // },
          acl: 'public-read',
          contentType: multerS3.AUTO_CONTENT_TYPE,
          shouldTransform : function (req, file, cb) {
              console.log('in should transform ', file)
              cb(null, /^image/i.test(file.mimetype))
          },
          transforms: [{
              id: 'original',
              key: function (req, file, cb) {
                  console.log('original')
                  cb(null, "original")
              },
              transform: function (req, file, cb) {
                  console.log('original1')
  
                  cb(null, sharp().jpg())
              }
          }, {
              id: 'thumbnail',
              key: function (req, file, cb) {
                  console.log('thumbnail')
  
                  cb(null, "thumbnail")
              },
              transform: function (req, file, cb) {
                  console.log('thumbnail1')
  
                  cb(null, file.resize(100, 100).jpg())
              }
          }]
      })
  })
  
  
   app.post('/upload', upload.single('image'), extendTimeout, function(req, res, next) {
          console.log('filessss ', req.file )
          res.send('Successfully uploaded ' + req.file + ' files!')
      })
  </code></pre>
  
  <p>Original image is uploaded successfully but resized image is not. Can anyone please guide me?</p>
  
  <p>Thanks</p>