In my node.js app, I'm using [gm (a graphicsmagick wrapper)][1] and [aws2js (amazon cli wrapper)][2]. The problem is that Amazon needs to know the content-length so that I can put the stream on S3. I'm uploading an image to my app, read that file by creating a stream: var fileStream=fs.createReadStream(file.path) I pass that file to gm, resize it and then tell it to stream that file. I then want to put that stream to aws: gm( fileStream, "some.png" ). identify({bufferStream: true}, function(err, info) { this.stream("png", function (err, stdout, stderr) { if (err){console.log(err);cb(err);return;} aws.S3.putStream(path, stdout, 'public-read', {'content-length': ?????, 'content-type': 'image/png'}, function (err, result) { ..... } }); }); }); The problem is that Amazon needs to know the content-length (its not the library) to put the stream. AWS doesn't support chunked streams. Does anyone know how I could determine the content-length of a stream? Or would the only solution be to tmp write it to the disk, read the file as a stream and then put it to amazon with the content-length of the temp file? [1]: https://github.com/aheckmann/gm [2]: https://github.com/SaltwaterC/aws2js
Did you ever figure this out? I'm trying to do exactly the same thing...