There were several issues:
1. With Google Cloud Storage, we can't override the Content-Type with
Response-Content-Type once it is set. Setting the value to
`application/octet-stream` doesn't buy us anything. GCS defaults to
`application/octet-stream`, and AWS uses `binary/octet-stream`. Just remove
this `Content-Type` when we upload new files.
2. CarrierWave and fog-google need to support query parameters:
https://github.com/fog/fog-google/pull/409/files, https://github.com/carrierwaveuploader/carrierwave/pull/2332/files.
CarrierWave has been monkey-patched until an official release.
3. Workhorse also needs to remove the Content-Type header in the request
(ef80978ff8/internal/objectstore/object.go (L66)),
or we'll get a 403 error when uploading due to signed URLs not matching the headers.
Upgrading to Workhorse 6.1.0 for https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/297
will make Workhorse use the headers that are used by Rails.
Closes#49957
As revealed in https://gitlab.com/gitlab-org/gitlab-ce/issues/49957, 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:
1. In the `/uploads/authorize` request, Rails can return a `StoreHeaders` key-value
pair in the JSON response containing the required headers that the PUT
request must include.
2. Use those HTTP headers if that value is present.
3. For backwards compatibility, if that key is not present, default to
the old behavior of sending the fixed `Content-Type` header.
See https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/297 as well.
