{
  lib,
  config,
  ...
}: let
  longhornVolumeOpts = {name, ...}: {
    options = {
      storage = lib.mkOption {
        type = lib.types.str;
      };

      namespace = lib.mkOption {
        type = lib.types.str;
        default = "default";
      };
    };
  };

  longhornPVOpts = {name, ...}: {
    options = {
      storage = lib.mkOption {
        type = lib.types.str;
      };
    };
  };

  longhornPVCOpts = {name, ...}: {
    options = {
      volumeName = lib.mkOption {
        type = lib.types.str;
        default = name;
      };

      # TODO: ideally we take this from the longhornPV so we don't duplicate this information.
      storage = lib.mkOption {
        type = lib.types.str;
      };
    };
  };
in {
  options = {
    lab.longhornVolumes = lib.mkOption {
      type = with lib.types; attrsOf (submodule longhornVolumeOpts);
      default = {};
    };

    lab.longhorn = {
      persistentVolume = lib.mkOption {
        type = with lib.types; attrsOf (submodule longhornPVOpts);
        default = {};
      };

      persistentVolumeClaim = lib.mkOption {
        type = with lib.types; attrsOf (submodule longhornPVCOpts);
        default = {};
      };
    };
  };

  config = {
    kubernetes.resources = {
      persistentVolumes =
        lib.mergeAttrs
        (builtins.mapAttrs
          (name: longhornVolume: {
            spec = {
              accessModes = ["ReadWriteOnce"];
              capacity.storage = longhornVolume.storage;
              persistentVolumeReclaimPolicy = "Delete";
              volumeMode = "Filesystem";

              claimRef = {
                inherit name;
                namespace = longhornVolume.namespace;
              };

              csi = {
                driver = "driver.longhorn.io";
                fsType = "ext4";
                volumeHandle = name;

                volumeAttributes = {
                  dataLocality = "disabled";
                  fromBackup = "";
                  fsType = "ext4";
                  numberOfReplicas = "2";
                  staleReplicaTimeout = "30";
                  unmapMarkSnapChainRemoved = "ignored";

                  recurringJobSelector = lib.generators.toYAML {} [
                    {
                      name = "backup-nfs";
                      isGroup = false;
                    }
                  ];
                };
              };
            };
          })
          config.lab.longhornVolumes)
        (builtins.mapAttrs
          (name: longhornPV: {
            spec = {
              accessModes = ["ReadWriteOnce"];
              capacity.storage = longhornPV.storage;
              persistentVolumeReclaimPolicy = "Delete";
              volumeMode = "Filesystem";

              csi = {
                driver = "driver.longhorn.io";
                fsType = "ext4";
                volumeHandle = name;

                volumeAttributes = {
                  dataLocality = "disabled";
                  fromBackup = "";
                  fsType = "ext4";
                  numberOfReplicas = "2";
                  staleReplicaTimeout = "30";
                  unmapMarkSnapChainRemoved = "ignored";

                  recurringJobSelector = lib.generators.toYAML {} [
                    {
                      name = "backup-nfs";
                      isGroup = false;
                    }
                  ];
                };
              };
            };
          })
          config.lab.longhorn.persistentVolume);

      persistentVolumeClaims =
        lib.mergeAttrs
        (builtins.mapAttrs
          (name: longhornVolume: {
            spec = {
              accessModes = ["ReadWriteOnce"];
              resources.requests.storage = longhornVolume.storage;
              storageClassName = "";
            };
          })
          config.lab.longhornVolumes)
        (builtins.mapAttrs
          (name: longhornPVC: {
            spec = {
              accessModes = ["ReadWriteOnce"];
              resources.requests.storage = longhornPVC.storage;
              storageClassName = "";
              volumeName = longhornPVC.volumeName;
            };
          })
          config.lab.longhorn.persistentVolumeClaim);
    };
  };
}