multer-s3 issue

gistfile1.txt

var AWS = require('aws-sdk');

AWS.config.region = 'us-west-2';

AWS.config.update({
    accessKeyId: process.env.AWS_ACCESS_KEY_ID,
    secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY
});

var s3 = new AWS.S3({params: {Bucket: process.env.S3_BUCKET_NAME}});

var multer = require('multer');
var multerS3 = require('multer-s3');
var upload = multer({
  storage: multerS3({
    s3: s3,
    bucket: process.env.S3_BUCKET_NAME,
    metadata: function (req, file, cb) {
      console.log("File: " + file.key); // These output undefined.
      console.log("File: " + file.location);
      cb(null, {fieldName: file.fieldname});
    },
    key: function (req, file, cb) {
      console.log(file.key);
      console.log(file.location);
      cb(null, Date.now().toString());
    }
  })
});


router.post('/upload', upload.any(), function(req, res){
  console.log("successfully uploaded");
  res.status(200);
  console.log("filepath " + req.files[0].filename);
  res.json({ filepath: '/images/' + req.files[0].filename });
});


/**** 
The console output here is:
file: undefined
file: undefined
successfully uploaded
filepath undefined
POST /api/upload 200 1507.201 ms - 32
GET /images/undefined 304 1.151 ms - -
******/