Send file in memory to API from Node Express

I've an API in Node and Express which is receiving a file from a the client (Postman in development) and I use multer to get the file in memory like this:

router.post('/api/v1/upload', contrl.upload, contrl.uploadFile);

and then in my controller:

exports upload = multer({ storage: multer.memoryStorage() }).single('file');

Now I can access the file with req.file.buffer, but then I want to send this same file to another API. I'm using request-promise-native so this would be something like this:

const rp = require('request-promise-native')

exports.uploadFile = (req, res) => {

  const options = {
    method: 'POST',
    uri: `${uri}`,
    form: {
      file: req.file.buffer
    }
  }

  rp(options)
    .then(parsedBody => {
      return res.status(201).send(parsedBody);
    })
    .catch(err => res.status(400).send(err));
}

I removed some other params for simplicity, but this is not working, probably because Node doesn´t know how to handle the info inside req.file.buffer.

How can I achieve this? Thanks

via David