Node.js stream upload directly to Google Cloud Sto

I have a Node.js app running on a Google Compute VM instance that receives file uploads directly from POST requests (not via the browser) and streams the incoming data to Google Cloud Storage (GCS).

I'm using Restify b/c I don't need the extra functionality of Express and because it makes it easy to stream the incoming data.

I create a random filename for the file, take the incoming req and toss it to a neat little Node wrapper for GCS (found here: https://github.com/bsphere/node-gcs) which makes a PUT request to GCS. The documentation for GCS using PUT can be found here: https://developers.google.com/storage/docs/reference-methods#putobject ... it says Content-Length is not necessary if using chunked transfer encoding.

Good news: the file is being created inside the appropriate GCS storage "bucket"!

Bad News:

I haven't figured out how to get the incoming file's extension from Restify (notice I'm manually setting '.jpg' and the content-type manually).
The file is experiencing slight corruption (almost certainly do to something I'm doing wrong with the PUT request). If I download the POSTed file from Google, OSX tells me its damaged ... BUT, if I use PhotoShop, it opens and looks just fine.

Update / Solution

As pointed out by vkurchatkin, I needed to parse the request object instead of just piping the whole thing to GCS. After trying out the lighter busboy module, I decided it was just a lot easier to use multiparty. For dynamically setting the Content-Type, I simply used Mimer (https://github.com/heldr/mimer), referencing the file extension of the incoming file. It's important to note that since we're piping the part object, the part.headers must be cleared out. Otherwise, unintended info, specifically content-type, will be passed along and can/will conflict with the content-type we're trying to set explicitly.

Here's the applicable, modified code:

var restify = require('restify'),
    server = restify.createServer(),
    GAPI = require('node-gcs').gapitoken,
    GCS = require('node-gcs'),
    multiparty = require('multiparty'),
    Mimer = require('mimer');

server.post('/upload', function(req, res) {

    var form = new multiparty.Form();

    form.on('part', function(part){
        var fileType = '.' + part.filename.split('.').pop().toLowerCase();
        var fileName = Math.random().toString(36).slice(2) + fileType;

        // clear out the part's headers to prevent conflicting data being passed to GCS
        part.headers = null;

        var gapi = new GAPI({
            iss: '-- your -- @developer.gserviceaccount.com',
            scope: 'https://www.googleapis.com/auth/devstorage.full_control',
            keyFile: './key.pem'
        }, 
        function(err) {
            if (err) { console.log('google cloud authorization error: ' + err); }

            var headers = {
                'Content-Type': Mimer(fileType),
                'Transfer-Encoding': 'Chunked',
                'x-goog-acl': 'public-read'
            };

            var gcs = new GCS(gapi);

            gcs.putStream(part, myBucket, '/' + fileName, headers, function(gerr, gres){
                console.log('file should be there!');
            });
        });
    });
};

You can't use the raw req stream since it yields whole request body, which is multipart. You need to parse the request with something like multiparty give you a readable steam and all metadata you need.