Fix attachments not displaying inline with Google Cloud Storage

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
(https://gitlab.com/gitlab-org/gitlab-workhorse/blob/ef80978ff89e628c8eeb66556720e30587d3deb6/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

1 files changed, 15 insertions, 1 deletions

diff --git a/app/controllers/concerns/send_file_upload.rb b/app/controllers/concerns/send_file_upload.rb
index 237c93daee8..382ec91f771 100644
--- a/app/controllers/concerns/send_file_upload.rb
+++ b/app/controllers/concerns/send_file_upload.rb
@@ -1,7 +1,11 @@
 module SendFileUpload
   def send_upload(file_upload, send_params: {}, redirect_params: {}, attachment: nil, disposition: 'attachment')
     if attachment
-      redirect_params[:query] = { "response-content-disposition" => "#{disposition};filename=#{attachment.inspect}" }
+      # Response-Content-Type will not override an existing Content-Type in
+      # Google Cloud Storage, so the metadata needs to be cleared on GCS for
+      # this to work. However, this override works with AWS.
+      redirect_params[:query] = { "response-content-disposition" => "#{disposition};filename=#{attachment.inspect}",
+                                  "response-content-type" => guess_content_type(attachment) }
       # By default, Rails will send uploads with an extension of .js with a
       # content-type of text/javascript, which will trigger Rails'
       # cross-origin JavaScript protection.
@@ -18,4 +22,14 @@ module SendFileUpload
       redirect_to file_upload.url(**redirect_params)
     end
   end
+
+  def guess_content_type(filename)
+    types = MIME::Types.type_for(filename)
+
+    if types.present?
+      types.first.content_type
+    else
+      "application/octet-stream"
+    end
+  end
 end