code: function tempRedirect(req, res) {
          var params = {
              Bucket: S3_BUCKET,
              Key: checkTrailingSlash(getFileKeyDir(req)) + req.params[0]
          };
          var s3 = getS3();
          s3.getSignedUrl('getObject', params, function(err, url) {
              res.redirect(url);
          });
      }
docs: Redirects image requests with a temporary signed URL, giving access
  to GET an upload.