-- Cover photos for albums and songs: covers/album/<id>-<time>.<ext>, covers/track/<id>-<time>.<ext>.
-- Anyone can view them (the app shows them to guests too); only admins upload, replace or delete.
insert into storage.buckets (id, name, public, file_size_limit, allowed_mime_types)
values ('covers', 'covers', true, 5242880, array['image/jpeg','image/png','image/webp'])
on conflict (id) do nothing;

create policy nk_admin_covers on storage.objects for all to authenticated
  using (bucket_id = 'covers' and public.is_admin())
  with check (bucket_id = 'covers' and public.is_admin());