I've managed to make a little more progress:

{
  disko.devices = let
    nixosPartitions = {
      ESP = {
        size = "512M";
        type = "EF00";
        content.type = "filesystem";
        content.format = "vfat";
        content.mountpoint = "/boot";
      };
      zfs = {
        size = "100%";
        content.type = "zfs";
        content.pool = "zpool-nixos";
      };
    };
  in {
    disk = {
      # NixOS boot mirror (240GBx2)
      ssd0 = {
        device = "/dev/sda";
        type = "disk";
        content = {
          type = "gpt";
          partitions = nixosPartitions;
        };
      };
      ssd1 = {
        device = "/dev/sdb";
        type = "disk";
        content = {
          type = "gpt";
          partitions = nixosPartitions;
        };
      };
    };

    zpool = {
      # NixOS boot mirror
      zpool-nixos = {
        type = "zpool";
        mode = "mirror";
        options = { ashift = "12"; };
        preCreateHook = ''
          # Create the temporary keyfile before any ZFS dataset is created
          head -c 32 /dev/urandom > /run/tmp-zfskey
          chmod 600 /run/tmp-zfskey
        '';
        datasets = {
          "root" =
            { # NOTE: Don't encrypt root dataset directly to allow flexibility later.
              type = "zfs_fs";
              mountpoint = "/";
            };
          "root/unlock" = {
            type = "zfs_fs";
            mountpoint = "/unlock";
            options = {
              encryption = "aes-256-gcm";
              keyformat = "passphrase";
              keylocation = "prompt";
            };
          };
          "root/nix" = {
            type = "zfs_fs";
            mountpoint = "/nix";
            options = {
              encryption = "aes-256-gcm";
              keyformat = "raw";
              keylocation = "file:///run/tmp-zfskey";
            };
          };
          "root/home" = {
            type = "zfs_fs";
            mountpoint = "/home";
            options = {
              encryption = "aes-256-gcm";
              keyformat = "raw";
              keylocation = "file:///run/tmp-zfskey";
            };
          };
        };
        postCreateHook = ''
          # Move the keyfile into the unlock dataset
          # cp /run/tmp-zfskey /mnt/unlock/zfskey
          # chmod 600 /mnt/unlock/zfskey

          echo "postCreateHook running" >> /tmp/disko-debug.log
          ls -lah /mnt/unlock >> /tmp/disko-debug.log 2>&1
          echo "before" >> /tmp/disko-debug.log 2>&1
          cp /run/tmp-zfskey /mnt/unlock/zfskey >> /tmp/disko-debug.log 2>&1
          echo "after" >> /tmp/disko-debug.log 2>&1
          chmod 600 /mnt/unlock/zfskey >> /tmp/disko-debug.log 2>&1
          ls -lah /mnt/unlock >> /tmp/disko-debug.log 2>&1

          # Update keylocation for other datasets (will be correct after reboot)
          zfs set keylocation=file:///unlock/zfskey zpool-nixos/root/nix
          zfs set keylocation=file:///unlock/zfskey zpool-nixos/root/home
        '';
      };
    };
  };
}

This mostly runs, but the postCreateHook has an issue with copying the key file. Not sure if I am going about this the right way, so any pointers would be much appreciated. I basically want to have just one dataset encrypted with a password, and then have all other encrypted datasets reference a key file stored on the password protected one so that I can unlock everything with just one password.

Are there any good examples of how to use the topsorted function? Doing some digging in nix repl for the mdadm example, I see this behavior:

nix-repl> inputs.nixpkgs.lib.lists.last nixosConfigurations.testmachine.config.disko.devices._meta.dev[
  "disk"
  "/dev/my-disk"
]

nix-repl> builtins.head nixosConfigurations.testmachine.config.disko.devices._meta.deviceDependencies.mdadm.raid1
[
  "disk"
  "/dev/my-disk"
]

Seems a bit odd only one element is in the list. And I wonder if this is why my new types are not getting ordered properly, because they follow the same structure as mdadm/mdraid.

Are there any good examples of how to use the topsorted function? Doing some digging in nix repl for the mdadm example, I see this behavior:

nix-repl> inputs.nixpkgs.lib.lists.last nixosConfigurations.testmachine.config.disko.devices._meta.deviceDependencies.mdadm.raid1[
  "disk"
  "/dev/my-disk"
]

nix-repl> builtins.head nixosConfigurations.testmachine.config.disko.devices._meta.deviceDependencies.mdadm.raid1
[
  "disk"
  "/dev/my-disk"
]

Seems a bit odd only one element is in the list. And I wonder if this is why my new types are not getting ordered properly, because they follow the same structure as mdadm/mdraid.

Are there any good examples of how to use the topsorted function? Doing some digging in nix repl for the mdadm example, I see this behavior:

nix-repl> inputs.nixpkgs.lib.lists.last nixosConfigurations.testmachine.config.disko.devices._meta.deviceDependencies.mdadm.raid1
[
  "disk"
  "/dev/my-disk"
]

nix-repl> builtins.head nixosConfigurations.testmachine.config.disko.devices._meta.deviceDependencies.mdadm.raid1
[
  "disk"
  "/dev/my-disk"
]

Seems a bit odd only one element is in the list. And I wonder if this is why my new types are not getting ordered properly, because they follow the same structure as mdadm/mdraid.

Are there any good examples of how to use the sortDevicesByDependencies function? Doing some digging in nix repl for the mdadm example, I see this behavior:

nix-repl> inputs.nixpkgs.lib.lists.last nixosConfigurations.testmachine.config.disko.devices._meta.deviceDependencies.mdadm.raid1
[
  "disk"
  "/dev/my-disk"
]

nix-repl> builtins.head nixosConfigurations.testmachine.config.disko.devices._meta.deviceDependencies.mdadm.raid1
[
  "disk"
  "/dev/my-disk"
]

Seems a bit odd only one element is in the list. And I wonder if this is why my new types are not getting ordered properly, because they follow the same structure as mdadm/mdraid.

reproduction steps:

      nixosConfigurations.testmachine = lib.nixosSystem {
        system = "x86_64-linux";
        modules = [
          ./tests/disko-install/configuration.nix
          # ./example/hybrid.nix
          ./module.nix
          # ./example/bcachefs-multi-disk.nix
          # ./example/mdadm.nix
          ./example/zfs-with-vdevs.nix
        ];

• add different examples to load and play around with
• load the flake into nix repl
• look at some of the _meta.deviceDependencies

reproduction steps:

      nixosConfigurations.testmachine = lib.nixosSystem {
        system = "x86_64-linux";
        modules = [
          ./tests/disko-install/configuration.nix
          # ./example/hybrid.nix
          ./module.nix
          # ./example/bcachefs-multi-disk.nix
          # ./example/mdadm.nix
          ./example/zfs-with-vdevs.nix
        ];

• add different examples to load and play around with toggling various configs
• load the flake into nix repl
• look at some of the _meta.deviceDependenciese

In reply to @lassulus:lassul.us
I will try to add that to my thaigersprint todo list tomorrow :D

In reply to @lassulus:lassul.us
I will try to add that to my thaigersprint todo list tomorrow :D