You have a production app with already uploaded attachments. However, you've realized that the existing store folder structure for attachments isn't working for you.
The first step is to change the location, by overriding
#generate_location or with the pretty_location plugin, and deploy that change. This will make any new files upload to the desired location, attachments on old locations will still continue to work normally.
The next step is to run a script that will move old files to new locations. The easiest way to do that is to reupload them and delete them.
Shrine has a method exactly for that,
Attacher#promote, which also handles the situation when someone attaches a new file during “moving” (since we're running this script on live production).
Shrine.plugin :delete_promoted User.paged_each do |user| attacher = user.avatar_attacher attacher.promote(action: :migrate) if attacher.stored? # use `attacher._promote(action: :migrate)` if you want promoting to be backgrounded end
:action is not mandatory, it's just for better introspection when monitoring background jobs and logs.
Now all your existing attachments should be happily living on new locations.