Dragonfly::FileDataStore::UnableToFormUrl: you need to configure server_root for Dragonfly::FileDataStore in order to form urls

[ttmthanh]

When I use dragonfly datastore s3 for upload image, I got error when trying use remote_url.
And if I use Dragonfly.app.remote_url_for(images.first.image_uid) --> Images no such key