refactor(modules/hardware/drives): move disko config to a module

modules/nixos/hardware/btrfs.nix

@@ -1,32 +1,12 @@
-{lib, device, ...}:
+{lib, config, ...}:
+let
+  cfg = config.hardware.drives.btrfs;
+in
 {
-  boot.initrd.postDeviceCommands = lib.mkAfter ''
+  config = lib.mkIf (cfg.enable) (lib.mkMerge [
-    mkdir /btrfs_tmp
+    {
-    mount /dev/root_vg/root /btrfs_tmp
-    if [[ -e /btrfs_tmp/root ]]; then
-        mkdir -p /btrfs_tmp/old_roots
-        timestamp=$(date --date="@$(stat -c %Y /btrfs_tmp/root)" "+%Y-%m-%-d_%H:%M:%S")
-        mv /btrfs_tmp/root "/btrfs_tmp/old_roots/$timestamp"
-    fi
-
-    delete_subvolume_recursively() {
-        IFS=$'\n'
-        for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
-            delete_subvolume_recursively "/btrfs_tmp/$i"
-        done
-        btrfs subvolume delete "$1"
-    }
-
-    for i in $(find /btrfs_tmp/old_roots/ -maxdepth 1 -mtime +30); do
-        delete_subvolume_recursively "$i"
-    done
-
-    btrfs subvolume create /btrfs_tmp/root
-    umount /btrfs_tmp
-  '';
-
   disko.devices.disk.main = {
-    inherit device;
+  device = cfg.drive;
     type = "disk";
     content.type = "gpt";
     content.partitions = {
@@ -68,4 +48,32 @@
 			"/nix".mountOptions = ["subvol=nix" "noatime"];
 		};
 	};
+    }
+    (lib.mkIf (cfg.ephemeralRoot) {
+	  boot.initrd.postDeviceCommands = lib.mkAfter ''
+	    mkdir /btrfs_tmp
+	    mount /dev/root_vg/root /btrfs_tmp
+	    if [[ -e /btrfs_tmp/root ]]; then
+		mkdir -p /btrfs_tmp/old_roots
+		timestamp=$(date --date="@$(stat -c %Y /btrfs_tmp/root)" "+%Y-%m-%-d_%H:%M:%S")
+		mv /btrfs_tmp/root "/btrfs_tmp/old_roots/$timestamp"
+	    fi
+
+	    delete_subvolume_recursively() {
+		IFS=$'\n'
+		for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
+		    delete_subvolume_recursively "/btrfs_tmp/$i"
+		done
+		btrfs subvolume delete "$1"
+	    }
+
+	    for i in $(find /btrfs_tmp/old_roots/ -maxdepth 1 -mtime +30); do
+		delete_subvolume_recursively "$i"
+	    done
+
+	    btrfs subvolume create /btrfs_tmp/root
+	    umount /btrfs_tmp
+	  '';
+    })
+  ]);
 }

modules/nixos/hardware/default.nix

@@ -0,0 +1,15 @@
+{lib,...}:
+{
+  imports = [
+    ./btrfs.nix
+  ];
+
+  options = {
+    hardware.drives.btrfs.enable = lib.mkEnableOption "";
+    hardware.drives.btrfs.drive = lib.mkOption {
+      type = lib.types.str;
+      default = "";
+    }; 
+    hardware.drives.btrfs.ephemeralRoot = lib.mkEnableOption "";
+  };
+}

systems/x86_64-linux/nemesis/default.nix

@@ -1,10 +1,10 @@
-{ config, lib, pkgs, modulesPath, ... }:
+{ config, lib, pkgs, ... }:
 {
-  imports =
+  hardware.drives.btrfs = {
-    [ 
+    enable = true;
-      (modulesPath + "/installer/scan/not-detected.nix")
+    drive = "/dev/disk/by-id/nvme-CT2000P3SSD8_2325E6E77434";
-      (import ./disko.nix {inherit lib; device = "/dev/disk/by-id/nvme-CT2000P3SSD8_2325E6E77434";})
+    ephemeralRoot = true;
-    ];
+  };
 
   boot.initrd.availableKernelModules = [ "nvme" "xhci_pci" "ahci" "usbhid" "usb_storage" "sd_mod" ];
   boot.initrd.kernelModules = [ "dm-snapshot" ];