Allow S3 Server Side Encryption
At the moment it's not possible to use S3 server side encryption, from what I can see (https://gitlab.com/gitlab-org/gitlab-ce/blob/bf7315cb13eab0cd1427efe29ce110a963b63c34/lib/backup/manager.rb#L49) is handling the upload to S3. It would be good if this could be specified and users could have at-rest encryption with S3.
I'm happy to explore adding this further myself, it would be good to know if the maintainers have any thoughts on doing this as it's obviously specific to one of the potential upload services.