{ ... }:
{
  # Don't make the nix store read-only, as this would prevent the overlay FS
  # from being able to mount it.
  boot.readOnlyNixStore = false;

  # Mount the hut nix store via NFS in read-only mode.
  fileSystems."/mnt/hut-nix-store" = {
    device = "hut:/nix/store";
    fsType = "nfs";
    options = [ "ro" ];
  };

  # A workdir is also needed, so setup a permanent dir using tmpfiles.
  systemd.tmpfiles.rules = [
    "d /mnt/nix-work 0700 root root -"
  ];

  # Mount an overlay in /nix/store using as lower layer the NFS store and upper
  # layer the disk nix store. The destination is still the nix store in
  # /nix/store (confusing). We need rw access, as the daemon need to write the
  # lock files to build derivations locally.
  fileSystems."/nix/store" = {
    device = "overlay";
    fsType = "overlay";
    options = [ "lowerdir=/mnt/hut-nix-store,upperdir=/nix/store,workdir=/mnt/nix-work" ];
    depends = [ "/nix/store" "/mnt/hut-nix-store" "/mnt/nix-work" ];
  };
}