Unable to play mp4 video uploaded to AWS S3 using pre-signed URL

Question

I'm uploading a mp4 video to AWS S3 using a pre-signed URL, the upload succeeds but when I try to download the video from S3 and play it in a media player (VLC or quickTime), it doesn't play!.

Generated pre-signed URL works fine with mp3 but the same problem as above also occurs for WAV and FLAC.

Code to generate the pre-signed url:

public String getPreSignedS3Url( final String userId, final String fileName )
    {
        Date expiration = new Date();
        long expTimeMillis = expiration.getTime();
        expTimeMillis += urlExpiry;
        expiration.setTime(expTimeMillis);

        String objectKey = StringUtils.getObjectKey( userId, fileName );

        GeneratePresignedUrlRequest generatePresignedUrlRequest = new GeneratePresignedUrlRequest(
                recordingBucketName, objectKey)
                .withMethod(HttpMethod.PUT)
                .withExpiration(expiration);

        URL url = s3Client.generatePresignedUrl(generatePresignedUrlRequest);

        return url.toString();

    }

After I get the pre-signed URL from the method above, I make a HTTP PUT request from Postman with the multipart/form-data in the request body like this:

-H 'content-type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW' \
  -F 'file=@/Users/john/Downloads/sampleDemo.mp4'

pre-signed url looks like this:

https://meeting-recording.s3.eu-west-2.amazonaws.com/331902257/sampleDemo.mp4?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20190720T125751Z&X-Amz-SignedHeaders=host&X-Amz-Expires=3599&X-Amz-Credential=AKIAZDSMLZ3VDKNXQUXH%2F20190720%2Feu-west-2%2Fs3%2Faws4_request&X-Amz-Signature=dfb8054f0738e07e925e9880e4a8e5ebba0a1bd3c84a3ec78913239f65221992

I tried to set the content type to mp4 in the getPreSignedS3Url() method using generatePresignedUrlRequest.setContentType( "video/mp4" ); and add Content-Type : "video/mp4" in the HTTP PUT request header but it didn't work and it fails with an error Signature doesn't match.

I'm using S3 as my personal back-up hard-drive, I expect to upload video and audio files to S3 using a pre-signed URL, download them at some point in the future and be able to play them, but I'm unable to play them after I have downloaded them.

Does anyone know what could be causing this?

Answer 1

PUT requests to S3 don't support multipart/form-data. The request body needs to contain nothing but the binary object data. If you download your existing file from S3 and open it with a text editor, you'll find that S3 has preserved the multipart form structure inside the file, instead of interpreting it as a wrapper for the actual payload.