nixos-config/modules/hosts/nixberry/disko.nix

{
  flake.modules.nixos."hosts/nixberry" =
    {
      inputs,
      lib,
      ...
    }:
    let
      firmwarePartition = lib.recursiveUpdate {
        # label = "FIRMWARE";
        priority = 1;

        type = "0700"; # Microsoft basic data
        attributes = [
          0 # Required Partition
        ];

        size = "1024M";
        content = {
          type = "filesystem";
          format = "vfat";
          # mountpoint = "/boot/firmware";
          mountOptions = [
            "noatime"
            "noauto"
            "x-systemd.automount"
            "x-systemd.idle-timeout=1min"
          ];
        };
      };

      espPartition = lib.recursiveUpdate {
        # label = "ESP";

        type = "EF00"; # EFI System Partition (ESP)
        attributes = [
          2 # Legacy BIOS Bootable, for U-Boot to find extlinux config
        ];

        size = "1024M";
        content = {
          type = "filesystem";
          format = "vfat";
          # mountpoint = "/boot";
          mountOptions = [
            "noatime"
            "noauto"
            "x-systemd.automount"
            "x-systemd.idle-timeout=1min"
            "umask=0077"
          ];
        };
      };

    in
    {
      imports = [ inputs.disko.nixosModules.disko ];

      boot.supportedFilesystems = [ "zfs" ];
      networking.hostId = "8425e349";

      services.zfs = {
        autoScrub.enable = true;
        autoSnapshot.enable = true;
        trim.enable = true;
      };

      disko.devices = {
        disk = {
          ssd = {
            device = "/dev/sda";
            content = {
              type = "gpt";
              partitions = {
                zfs = {
                  size = "100%";
                  content = {
                    type = "zfs";
                    pool = "rpool";
                  };
                };
              };

            };
          };

          main = {
            device = "/dev/mmcblk0";
            content = {
              type = "gpt";
              partitions = {
                FIRMWARE = firmwarePartition {
                  label = "FIRMWARE";
                  content.mountpoint = "/boot/firmware";
                };
                ESP = espPartition {
                  label = "ESP";
                  content.mountpoint = "/boot";
                };
                # Swap Partition
                swap = {
                  size = "8G";
                  label = "swap";
                  content = {
                    type = "swap";
                    discardPolicy = "both";
                    resumeDevice = true;
                  };
                };

                zfs = {
                  size = "100%";
                  content = {
                    type = "zfs";
                    pool = "rpool"; # zroot
                  };
                };

              };
            };
          };
        };

        zpool = {
          rpool = {
            type = "zpool";
            options = {
              ashift = "12";
              autotrim = "on"; # see also services.zfs.trim.enable
            };

            rootFsOptions = {
              "com.sun:auto-snapshot" = "false";
              # https://jrs-s.net/2018/08/17/zfs-tuning-cheat-sheet/
              compression = "lz4";
              atime = "off";
              xattr = "sa";
              acltype = "posixacl";
              # https://rubenerd.com/forgetting-to-set-utf-normalisation-on-a-zfs-pool/
              normalization = "formD";
              dnodesize = "auto";
              mountpoint = "none";
              canmount = "off";
            };

            postCreateHook =
              let
                poolName = "rpool";
              in
              "zfs list -t snapshot -H -o name | grep -E '^${poolName}@blank$' || zfs snapshot ${poolName}@blank";

            datasets = {

              # stuff which can be recomputed/easily redownloaded, e.g. nix store
              local = {
                type = "zfs_fs";
                options.mountpoint = "none";
              };
              "local/nix" = {
                type = "zfs_fs";
                options = {
                  reservation = "128M";
                  mountpoint = "legacy"; # to manage "with traditional tools"
                };
                mountpoint = "/nix"; # nixos configuration mountpoint
              };

              # _system_ data
              system = {
                type = "zfs_fs";
                options = {
                  mountpoint = "none";
                };
              };
              "system/root" = {
                type = "zfs_fs";
                options = {
                  mountpoint = "legacy";
                };
                mountpoint = "/";
              };
              "system/var" = {
                type = "zfs_fs";
                options = {
                  mountpoint = "legacy";
                };
                mountpoint = "/var";
              };

              # _user_ and _user service_ data. safest, long retention policy
              safe = {
                type = "zfs_fs";
                options = {
                  copies = "2";
                  mountpoint = "none";
                };
              };
              "safe/home" = {
                type = "zfs_fs";
                options = {
                  mountpoint = "legacy";
                };
                mountpoint = "/home";
              };
              "safe/storage" = {
                type = "zfs_fs";
                options = {
                  mountpoint = "legacy";
                  "com.sun:auto-snapshot" = "true";
                };
                mountpoint = "/storage";
              };
              "safe/var/lib" = {
                type = "zfs_fs";
                options = {
                  mountpoint = "legacy";
                };
                mountpoint = "/var/lib";
              };

            };
          };
        };
      };

    };
}