nixos/hot-resize: init

nixos/modules/services/system/hot-resize.nix

@@ -0,0 +1,140 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  cfg = config.services.hotResize;
+in
+{
+  options.services.hotResize = {
+    enable = lib.mkEnableOption "the hot resize service for filesystems";
+
+    devices = lib.mkOption {
+      type = lib.types.listOf (
+        lib.types.submodule {
+          options = {
+            device = lib.mkOption {
+              type = lib.types.str;
+              example = "/dev/sda1";
+              description = "Block device path to resize";
+            };
+
+            fsType = lib.mkOption {
+              type = lib.types.enum [
+                "ext4"
+                "xfs"
+                "btrfs"
+              ];
+              default = "ext4";
+              description = "Filesystem type (supported: ext4, xfs, btrfs)";
+            };
+
+            mountPoint = lib.mkOption {
+              type = lib.types.str;
+              example = "/";
+              description = "Mount point of the filesystem to resize";
+            };
+          };
+        }
+      );
+      default = [ ];
+      example = lib.literalExpression ''
+        [
+          {
+            device = "/dev/sda1";
+            fsType = "ext4";
+            mountPoint = "/";
+          }
+          {
+            device = "/dev/sdb1";
+            fsType = "xfs";
+            mountPoint = "/data";
+          }
+        ]
+      '';
+      description = "List of devices to monitor for resizing";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    systemd.services.hotResize = {
+      description = "Hot resize service for filesystems";
+      wantedBy = [ "multi-user.target" ];
+
+      path = [
+        pkgs.parted
+        pkgs.cloud-utils
+        pkgs.coreutils
+        pkgs.util-linux
+        pkgs.e2fsprogs
+        pkgs.xfsprogs
+        pkgs.btrfs-progs
+      ];
+
+      serviceConfig = {
+        Type = "oneshot";
+        RemainAfterExit = false;
+        ExecStart = pkgs.writeShellScript "resize-fs" ''
+          set -euo pipefail
+
+          process_device() {
+            local device="$1"
+            local fstype="$2"
+            local mountpoint="$3"
+
+            echo "Processing $device ($fstype) mounted at $mountpoint..."
+
+            REAL_DEVICE=$(readlink -f "$device")
+            DISK=$(lsblk -ndo pkname $REAL_DEVICE)
+            PART_NUM=$(lsblk -ndo part $REAL_DEVICE)
+
+            if [ -z "$DISK" ] || [ -z "$PART_NUM" ]; then
+              echo "Failed to determine disk and partition number for $device"
+              return 1
+            fi
+
+            echo "Growing partition /dev/$DISK partition $PART_NUM..."
+            GROWPART_OUTPUT=$(growpart "/dev/$DISK" "$PART_NUM" 2>&1) || {
+              EXIT_CODE=$?
+              if [ $EXIT_CODE -eq 2 ]; then
+                echo "Partition is already at maximum size, continuing with filesystem resize..."
+              else
+                echo "Failed to grow partition: $GROWPART_OUTPUT"
+                return $EXIT_CODE
+              fi
+            }
+
+            echo "Resizing filesystem..."
+            case "$fstype" in
+              "ext4")
+                resize2fs "$device"
+                ;;
+              "xfs")
+                xfs_growfs "$mountpoint"
+                ;;
+              "btrfs")
+                btrfs filesystem resize max "$mountpoint"
+                ;;
+              *)
+                echo "Unsupported filesystem type: $fstype"
+                return 1
+                ;;
+            esac
+
+            echo "Current size:"
+            df -h "$mountpoint"
+            echo "---"
+          }
+
+          # Process each device in sequence
+          ${lib.concatMapStrings (dev: ''
+            process_device "${dev.device}" "${dev.fsType}" "${dev.mountPoint}"
+          '') cfg.devices}
+        '';
+      };
+    };
+  };
+}