Using react-dropzone-uploader with Google Cloud Storage

[leolabs]

I've tried using react-dropzone-uploader with GCS and couldn't get rid of CORS problems. After some trial-and-error, I found the problem. The requests are sent with an X-Requested-With header by default, which needs to be specifically allowed in GCS. To do that, create a JSON file with the following content:

[
  {
    "maxAgeSeconds": 3600,
    "method": ["GET", "HEAD", "PUT"],
    "origin": ["*"],
    "responseHeader": [
      "Content-Type",
      "Access-Control-Allow-Origin",
      "X-Requested-With"
    ]
  }
]

Then apply those rules to your bucket:

gsutil cors set the-json-file.json gs://your-bucket

It might be nice to include this in the docs for others who might have the same use case :)