modules.system.fileSystems.rollingRootfs: split

modules/system/fileSystems/default.nix

@@ -22,14 +22,6 @@ inputs:
           then if inputs.lib.hasPrefix "/dev/" (builtins.head swap) then builtins.head swap else null
           else null;
     };
-    rollingRootfs = mkOption
-    {
-      type = types.nullOr (types.submodule { options =
-      {
-        waitDevices = mkOption { type = types.listOf types.nonEmptyStr; default = []; };
-      };});
-      default = {};
-    };
   };
   config = let inherit (inputs.config.nixos.system) fileSystems; in inputs.lib.mkMerge
   [
@@ -88,69 +80,5 @@ inputs:
         };
       nixos.system.kernel.patches = [ "hibernate-progress" ];
     })
-    # rollingRootfs
-    (inputs.lib.mkIf (fileSystems.rollingRootfs != null)
-    {
-      boot.initrd.systemd =
-      {
-        extraBin =
-        {
-          grep = "${inputs.pkgs.gnugrep}/bin/grep";
-          awk = "${inputs.pkgs.gawk}/bin/awk";
-          chattr = "${inputs.pkgs.e2fsprogs}/bin/chattr";
-          lsmod = "${inputs.pkgs.kmod}/bin/lsmod";
-        };
-        services.roll-rootfs =
-        {
-          wantedBy = [ "initrd.target" ];
-          after = [ "cryptsetup.target" "systemd-hibernate-resume.service" ];
-          before = [ "local-fs-pre.target" "sysroot.mount" ];
-          unitConfig.DefaultDependencies = false;
-          serviceConfig.Type = "oneshot";
-          script =
-            let
-              device = inputs.config.fileSystems."/".device;
-              waitDevice = builtins.concatStringsSep "\n" (builtins.map
-                (device: "while ! [ -e ${device} ]; do sleep 1; done")
-                (fileSystems.rollingRootfs.waitDevices ++ [ device ]));
-            in
-            ''
-              # wait for device to be available
-              while ! lsmod | grep -q btrfs; do sleep 1; done
-              ${waitDevice}
-
-              # mount device
-              mount ${device} /mnt -m
-
-              # move old rootfs, create new one
-              if [ -f /mnt/nix/rootfs/current/.timestamp ]
-              then
-                timestamp=$(cat /mnt/nix/rootfs/current/.timestamp)
-                subvolid=$(btrfs subvolume show /mnt/nix/rootfs/current | grep 'Subvolume ID:' | awk '{print $NF}')
-                mv /mnt/nix/rootfs/current /mnt/nix/rootfs/$timestamp-$subvolid
-                btrfs property set -ts /mnt/nix/rootfs/$timestamp-$subvolid ro true
-              fi
-              [ -d /mnt/nix/rootfs/current ] || btrfs subvolume create /mnt/nix/rootfs/current
-              chattr +C /mnt/nix/rootfs/current
-              echo $(date '+%Y%m%d%H%M%S') > /mnt/nix/rootfs/current/.timestamp
-
-              # make systemd happy
-              mkdir -p /mnt/nix/rootfs/current/usr
-              touch /mnt/nix/rootfs/current/usr/make-systemd-happy
-
-              # backup persistent
-              if [ -d /mnt/nix/persistent/.bakcups ]
-              then
-                btrfs subvolume snapshot -r /mnt/nix/persistent \
-                  /mnt/nix/persistent/.bakcups/boot-$(date '+%Y%m%d%H%M%S')
-              fi
-
-              umount /mnt
-            '';
-        };
-      };
-    })
   ];
 }
-
-

modules/system/fileSystems/rollingRootfs.nix

@@ -0,0 +1,74 @@
+inputs:
+{
+  options.nixos.system.fileSystems.rollingRootfs = let inherit (inputs.lib) mkOption types; in mkOption
+  {
+    type = types.nullOr (types.submodule { options =
+    {
+      waitDevices = mkOption { type = types.listOf types.nonEmptyStr; default = []; };
+    };});
+    default = {};
+  };
+  config =
+    let inherit (inputs.config.nixos.system.fileSystems) rollingRootfs;
+    in inputs.lib.mkIf (rollingRootfs != null)
+    {
+      boot.initrd.systemd =
+      {
+        extraBin =
+        {
+          grep = "${inputs.pkgs.gnugrep}/bin/grep";
+          awk = "${inputs.pkgs.gawk}/bin/awk";
+          chattr = "${inputs.pkgs.e2fsprogs}/bin/chattr";
+          lsmod = "${inputs.pkgs.kmod}/bin/lsmod";
+        };
+        services.roll-rootfs =
+        {
+          wantedBy = [ "initrd.target" ];
+          after = [ "cryptsetup.target" "systemd-hibernate-resume.service" ];
+          before = [ "local-fs-pre.target" "sysroot.mount" ];
+          unitConfig.DefaultDependencies = false;
+          serviceConfig.Type = "oneshot";
+          script =
+            let
+              device = inputs.config.fileSystems."/".device;
+              waitDevice = builtins.concatStringsSep "\n" (builtins.map
+                (device: "while ! [ -e ${device} ]; do sleep 1; done")
+                (rollingRootfs.waitDevices ++ [ device ]));
+            in
+            ''
+              # wait for device to be available
+              while ! lsmod | grep -q btrfs; do sleep 1; done
+              ${waitDevice}
+
+              # mount device
+              mount ${device} /mnt -m
+
+              # move old rootfs, create new one
+              if [ -f /mnt/nix/rootfs/current/.timestamp ]
+              then
+                timestamp=$(cat /mnt/nix/rootfs/current/.timestamp)
+                subvolid=$(btrfs subvolume show /mnt/nix/rootfs/current | grep 'Subvolume ID:' | awk '{print $NF}')
+                mv /mnt/nix/rootfs/current /mnt/nix/rootfs/$timestamp-$subvolid
+                btrfs property set -ts /mnt/nix/rootfs/$timestamp-$subvolid ro true
+              fi
+              [ -d /mnt/nix/rootfs/current ] || btrfs subvolume create /mnt/nix/rootfs/current
+              chattr +C /mnt/nix/rootfs/current
+              echo $(date '+%Y%m%d%H%M%S') > /mnt/nix/rootfs/current/.timestamp
+
+              # make systemd happy
+              mkdir -p /mnt/nix/rootfs/current/usr
+              touch /mnt/nix/rootfs/current/usr/make-systemd-happy
+
+              # backup persistent
+              if [ -d /mnt/nix/persistent/.bakcups ]
+              then
+                btrfs subvolume snapshot -r /mnt/nix/persistent \
+                  /mnt/nix/persistent/.bakcups/boot-$(date '+%Y%m%d%H%M%S')
+              fi
+
+              umount /mnt
+            '';
+        };
+      };
+    };
+}