refactor(nixos): move btrfs config to its own module

modules/nixos/hardware/btrfs.nix

@@ -1,101 +0,0 @@
-{ lib, config, ... }:
-let
-  cfg = config.hardware.drives.btrfs;
-in
-{
-  config = lib.mkIf cfg.enable (
-    lib.mkMerge [
-      {
-        boot.initrd.kernelModules = [ "dm-snapshot" ];
-        disko.devices.disk.main = {
-          device = cfg.drive;
-          type = "disk";
-          content.type = "gpt";
-          content.partitions = {
-            boot.name = "boot";
-            boot.size = "1M";
-            boot.type = "EF02";
-            esp.name = "ESP";
-            esp.size = "500M";
-            esp.type = "EF00";
-            esp.content = {
-              type = "filesystem";
-              format = "vfat";
-              mountpoint = "/boot";
-            };
-            swap.size = "4G";
-            swap.content = {
-              type = "swap";
-              resumeDevice = true;
-            };
-            root.name = "root";
-            root.size = "100%";
-            root.content = {
-              type = "lvm_pv";
-              vg = "root_vg";
-            };
-          };
-        };
-
-        disko.devices.lvm_vg.root_vg = {
-          type = "lvm_vg";
-          lvs.root.size = "100%FREE";
-          lvs.root.content.type = "btrfs";
-          lvs.root.content.extraArgs = [ "-f" ];
-          lvs.root.content.subvolumes = {
-            "/root".mountpoint = "/";
-            "/persist".mountpoint = "/persist";
-            "/persist".mountOptions = [
-              "subvol=persist"
-              "noatime"
-            ];
-            "/nix".mountpoint = "/nix";
-            "/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
-          	  '';
-        programs.fuse.userAllowOther = true;
-        fileSystems."/persist".neededForBoot = true;
-        #FIXME: below should be in module or something
-        environment.persistence."/persist" = {
-          hideMounts = true;
-          files = [
-            "/etc/ssh/ssh_host_ed25519_key"
-            "/etc/ssh/ssh_host_ed25519_key.pub"
-            "/etc/ssh/ssh_host_rsa_key"
-            "/etc/ssh/ssh_host_rsa_key.pub"
-            "/etc/machine-id"
-          ];
-        };
-      })
-    ]
-  );
-}

modules/nixos/hardware/default.nix

@@ -1,27 +1,19 @@
 {
   lib,
   config,
-  pkgs,
   ...
 }:
 let
-  inherit (lib) mkIf mkEnableOption singleton;
+  inherit (lib) singleton;
-  cfg = config.hardware;
 in
 {
   imports = [
-    ./btrfs.nix
     ./nvidia.nix
     ./audio.nix
     ./networking.nix
   ];
 
   options.hardware = {
-    drives.btrfs = {
-      enable = lib.mkEnableOption "";
-      drive = lib.pantheon.mkStrOption;
-      ephemeralRoot = lib.mkEnableOption "";
-    };
     gpu = lib.pantheon.mkStrOption;
     platform = lib.pantheon.mkStrOption;
   };

modules/nixos/hardware/drives/btrfs/default.nix

@@ -0,0 +1,107 @@
+{ config, lib, ... }:
+let
+  inherit (lib) mkIf mkEnableOption;
+  inherit (lib.pantheon) mkStrOption;
+  cfg = config.hardware.drives.btrfs;
+  ephemeralRootCfg = {
+    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
+      	  '';
+    programs.fuse.userAllowOther = true;
+    fileSystems."/persist".neededForBoot = true;
+    #FIXME: below should be in module or something
+    environment.persistence."/persist" = {
+      hideMounts = true;
+      files = [
+        "/etc/ssh/ssh_host_ed25519_key"
+        "/etc/ssh/ssh_host_ed25519_key.pub"
+        "/etc/ssh/ssh_host_rsa_key"
+        "/etc/ssh/ssh_host_rsa_key.pub"
+        "/etc/machine-id"
+      ];
+    };
+  };
+in
+{
+  options.hardware.drives.btrfs = {
+    enable = mkEnableOption "";
+    drive = mkStrOption;
+    ephemeralRoot = mkEnableOption "";
+  };
+  config = mkIf cfg.enable (
+    {
+      boot.initrd.kernelModules = [ "dm-snapshot" ];
+      disko.devices.disk.main = {
+        device = cfg.drive;
+        type = "disk";
+        content.type = "gpt";
+        content.partitions = {
+          boot.name = "boot";
+          boot.size = "1M";
+          boot.type = "EF02";
+          esp.name = "ESP";
+          esp.size = "500M";
+          esp.type = "EF00";
+          esp.content = {
+            type = "filesystem";
+            format = "vfat";
+            mountpoint = "/boot";
+          };
+          swap.size = "4G";
+          swap.content = {
+            type = "swap";
+            resumeDevice = true;
+          };
+          root.name = "root";
+          root.size = "100%";
+          root.content = {
+            type = "lvm_pv";
+            vg = "root_vg";
+          };
+        };
+      };
+
+      disko.devices.lvm_vg.root_vg = {
+        type = "lvm_vg";
+        lvs.root.size = "100%FREE";
+        lvs.root.content.type = "btrfs";
+        lvs.root.content.extraArgs = [ "-f" ];
+        lvs.root.content.subvolumes = {
+          "/root".mountpoint = "/";
+          "/persist".mountpoint = "/persist";
+          "/persist".mountOptions = [
+            "subvol=persist"
+            "noatime"
+          ];
+          "/nix".mountpoint = "/nix";
+          "/nix".mountOptions = [
+            "subvol=nix"
+            "noatime"
+          ];
+        };
+      };
+    }
+    // ephemeralRootCfg
+  );
+}