clanCore: init machine_id.nix with clan.core.machine.{id,diskId}

nixosModules/clanCore/machine_id.nix

@@ -0,0 +1,58 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+
+let
+  cfg = config.clan.core.machine;
+in
+{
+  options.clan.core.machine = {
+    id = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      description = "The machine id";
+    };
+    idShort = lib.mkOption {
+      readOnly = true;
+      type = lib.types.nullOr lib.types.str;
+      description = "The short machine id";
+    };
+    diskId = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      description = "The disk id";
+    };
+  };
+
+  config = {
+    clan.core.machine.id =
+      lib.mkDefault
+        config.clan.core.facts.services."machine_id".public."machine_id".value;
+    clan.core.machine.idShort = if (cfg.id != null) then (lib.substring 0 8 cfg.id) else null;
+
+    clan.core.machine.diskId =
+      lib.mkDefault
+        config.clan.core.facts.services."machine_id".public."diskId".value;
+
+    clan.core.facts.services."machine_id" = {
+      public."machine_id" = { };
+      public."diskId" = { };
+      generator.path = [
+        pkgs.coreutils
+      ];
+      generator.script = ''
+        machine_uuid=$(dd if=/dev/urandom bs=1 count=16 2>/dev/null | od -An -tx1 | tr -d ' \n')
+        disk_uuid=$(dd if=/dev/urandom bs=1 count=3 2>/dev/null | od -An -tx1 | tr -d ' \n')
+        echo -n "$machine_uuid" > "$facts"/machine_id
+        echo -n "$disk_uuid" > "$facts"/diskId
+      '';
+    };
+
+    networking.hostId = lib.mkIf (cfg.id != null) (lib.mkDefault cfg.idShort);
+
+    boot.kernelParams = lib.mkIf (cfg.id != null) [
+      ''systemd.machine_id=${cfg.id}''
+    ];
+  };
+}