image: T4516: Added system image tools

This commit adds the whole set of system image tools written from the scratch in
Python that allows performing all the operations on images:

* check information
* perform installation and deletion
* versions management

Also, it contains a new service that will update the GRUB menu and keep tracking
its version in the future.

WARNING: The commit contains non-reversible changes. Because of boot menu
changes, it will not be possible to manage images from older VyOS versions after
an update.

1 files changed, 190 insertions, 0 deletions

diff --git a/src/op_mode/image_manager.py b/src/op_mode/image_manager.py
new file mode 100644
index 000000000..ac889da38
--- /dev/null
+++ b/src/op_mode/image_manager.py
@@ -0,0 +1,190 @@
+#!/usr/bin/env python3
+#
+# Copyright 2022 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This file is part of VyOS.
+#
+# VyOS is free software: you can redistribute it and/or modify it under the
+# terms of the GNU General Public License as published by the Free Software
+# Foundation, either version 3 of the License, or (at your option) any later
+# version.
+#
+# VyOS is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+# details.
+#
+# You should have received a copy of the GNU General Public License along with
+# VyOS. If not, see <https://www.gnu.org/licenses/>.
+
+from argparse import ArgumentParser, Namespace
+from pathlib import Path
+from shutil import rmtree
+from sys import exit
+
+from vyos.system import disk, grub, image
+from vyos.util import ask_yes_no
+
+
+def delete_image(image_name: str) -> None:
+    """Remove installed image files and boot entry
+
+    Args:
+        image_name (str): a name of image to delete
+    """
+    if image_name == image.get_running_image():
+        exit('Currently running image cannot be deleted')
+    if image_name == image.get_default_image():
+        exit('Default image cannot be deleted')
+    available_images: list[str] = grub.version_list()
+    if image_name not in available_images:
+        exit(f'The image "{image_name}" cannot be found')
+    presistence_storage: str = disk.find_persistence()
+    if not presistence_storage:
+        exit('Persistence storage cannot be found')
+
+    if not ask_yes_no(f'Do you really want to delete the image {image_name}?',
+                      default=False):
+        exit()
+
+    # remove files and menu entry
+    version_path: Path = Path(f'{presistence_storage}/boot/{image_name}')
+    try:
+        rmtree(version_path)
+        grub.version_del(image_name, presistence_storage)
+        print(f'The image "{image_name}" was successfully deleted')
+    except Exception as err:
+        exit(f'Unable to remove the image "{image_name}": {err}')
+
+
+def set_image(image_name: str) -> None:
+    """Set default boot image
+
+    Args:
+        image_name (str): an image name
+    """
+    if image_name == image.get_default_image():
+        exit(f'The image "{image_name}" already configured as default')
+    available_images: list[str] = grub.version_list()
+    if image_name not in available_images:
+        exit(f'The image "{image_name}" cannot be found')
+    presistence_storage: str = disk.find_persistence()
+    if not presistence_storage:
+        exit('Persistence storage cannot be found')
+
+    if not ask_yes_no(
+            f'Do you really want to set the image {image_name} '
+            'as default boot image?',
+            default=False):
+        exit()
+
+    # set default boot image
+    try:
+        grub.set_default(image_name, presistence_storage)
+        print(f'The image "{image_name}" is now default boot image')
+    except Exception as err:
+        exit(f'Unable to set default image "{image_name}": {err}')
+
+
+def rename_image(name_old: str, name_new: str) -> None:
+    """Rename installed image
+
+    Args:
+        name_old (str): old name
+        name_new (str): new name
+    """
+    if name_old == image.get_running_image():
+        exit('Currently running image cannot be renamed')
+    available_images: list[str] = grub.version_list()
+    if name_old not in available_images:
+        exit(f'The image "{name_old}" cannot be found')
+    if name_new in available_images:
+        exit(f'The image "{name_new}" already exists')
+    if not image.validate_name(name_new):
+        exit(f'The image name "{name_new}" is not allowed')
+
+    presistence_storage: str = disk.find_persistence()
+    if not presistence_storage:
+        exit('Persistence storage cannot be found')
+
+    if not ask_yes_no(
+            f'Do you really want to rename the image {name_old} '
+            f'to the {name_new}?',
+            default=False):
+        exit()
+
+    try:
+        # replace default boot item
+        if name_old == image.get_default_image():
+            grub.set_default(name_new, presistence_storage)
+
+        # rename files and dirs
+        old_path: Path = Path(f'{presistence_storage}/boot/{name_old}')
+        new_path: Path = Path(f'{presistence_storage}/boot/{name_new}')
+        old_path.rename(new_path)
+
+        # replace boot item
+        grub.version_del(name_old, presistence_storage)
+        grub.version_add(name_new, presistence_storage)
+
+        print(f'The image "{name_old}" was renamed to "{name_new}"')
+    except Exception as err:
+        exit(f'Unable to rename image "{name_old}" to "{name_new}": {err}')
+
+
+def list_images() -> None:
+    """Print list of available images for CLI hints"""
+    images_list: list[str] = grub.version_list()
+    for image_name in images_list:
+        print(image_name)
+
+
+def parse_arguments() -> Namespace:
+    """Parse arguments
+
+    Returns:
+        Namespace: a namespace with parsed arguments
+    """
+    parser: ArgumentParser = ArgumentParser(description='Manage system images')
+    parser.add_argument('--action',
+                        choices=['delete', 'set', 'rename', 'list'],
+                        required=True,
+                        help='action to perform with an image')
+    parser.add_argument(
+        '--image_name',
+        help=
+        'a name of an image to add, delete, install, rename, or set as default')
+    parser.add_argument('--image_new_name', help='a new name for image')
+    args: Namespace = parser.parse_args()
+    # Validate arguments
+    if args.action == 'delete' and not args.image_name:
+        exit('An image name is required for delete action')
+    if args.action == 'set' and not args.image_name:
+        exit('An image name is required for set action')
+    if args.action == 'rename' and (not args.image_name or
+                                    not args.image_new_name):
+        exit('Both old and new image names are required for rename action')
+
+    return args
+
+
+if __name__ == '__main__':
+    try:
+        args: Namespace = parse_arguments()
+        if args.action == 'delete':
+            delete_image(args.image_name)
+        if args.action == 'set':
+            set_image(args.image_name)
+        if args.action == 'rename':
+            rename_image(args.image_name, args.image_new_name)
+        if args.action == 'list':
+            list_images()
+
+        exit()
+
+    except KeyboardInterrupt:
+        print('Stopped by Ctrl+C')
+        exit()
+
+    except Exception as err:
+        exit(f'{err}')