Support adding PUT headers for object storage from Rails
As revealed in gitlab-ce#49957 (closed), Rails
generates a signed URL with a fixed HTTP header with
Content-Type: application/octet-stream. However, if we change or remove that for
some reason in Workhorse, this breaks the upload with a 403 Unauthorized because
the signed URL is not valid.
We can make this more robust by doing the following:
- In the
/uploads/authorizerequest, Rails can return a
PutHeaderskey-value pair in the JSON response containing the required headers that the PUT request must include.
- Use those HTTP headers if that value is present.
- For backwards compatibility, if that key is not present, default to
the old behavior of sending the fixed