image: T4516: support for interoperability of legacy/new image tools

This commit allows management of system images with either new or legacy
tools: 'add/delete/rename system image' and 'set default' are translated
appropriately on booting between images with the old and new tools.
Consequently, the warning of the initial commit of T4516 is dropped.

(cherry picked from commit 96b65e90fbfa1fe63d97929ac86fc910abb0caa9)

10 files changed, 486 insertions, 152 deletions

diff --git a/data/templates/grub/grub_compat.j2 b/data/templates/grub/grub_compat.j2
new file mode 100644
index 000000000..935172005
--- /dev/null
+++ b/data/templates/grub/grub_compat.j2
@@ -0,0 +1,58 @@
+{# j2lint: disable=S6 #}
+### Generated by VyOS image-tools v.{{ tools_version }} ###
+{% macro menu_name(mode) -%}
+{% if mode == 'normal' -%}
+    VyOS
+{%- elif mode == 'pw_reset' -%}
+    Lost password change
+{%- else -%}
+    Unknown
+{%- endif %}
+{%- endmacro %}
+{% macro console_name(type) -%}
+{% if type == 'tty' -%}
+    KVM
+{%- elif type == 'ttyS' -%}
+    Serial
+{%- elif type == 'ttyUSB' -%}
+    USB
+{%- else -%}
+    Unknown
+{%- endif %}
+{%- endmacro %}
+{% macro console_opts(type) -%}
+{% if type == 'tty' -%}
+    console=ttyS0,115200 console=tty0
+{%- elif type == 'ttyS' -%}
+    console=tty0 console=ttyS0,115200
+{%- elif type == 'ttyUSB' -%}
+    console=tty0 console=ttyUSB0,115200
+{%- else -%}
+    console=tty0 console=ttyS0,115200
+{%- endif %}
+{%- endmacro %}
+{% macro passwd_opts(mode) -%}
+{% if mode == 'pw_reset' -%}
+    init=/opt/vyatta/sbin/standalone_root_pw_reset
+{%- endif %}
+{%- endmacro %}
+set default={{ default }}
+set timeout={{ timeout }}
+{% if console_type == 'ttyS' %}
+serial --unit={{ console_num }} --speed=115200
+{% else %}
+serial --unit=0 --speed=115200
+{% endif %}
+terminal_output --append serial
+terminal_input serial console
+{% if efi %}
+insmod efi_gop
+insmod efi_uga
+{% endif %}
+
+{% for v in versions %}
+menuentry "{{ menu_name(v.bootmode) }} {{ v.version }} ({{ console_name(v.console_type) }} console)" {
+    linux /boot/{{ v.version }}/vmlinuz {{ v.boot_opts }} {{ console_opts(v.console_type) }} {{ passwd_opts(v.bootmode) }}
+    initrd /boot/{{ v.version }}/initrd.img
+}
+{% endfor %}
diff --git a/python/vyos/system/__init__.py b/python/vyos/system/__init__.py
index 403738e20..0c91330ba 100644
--- a/python/vyos/system/__init__.py
+++ b/python/vyos/system/__init__.py
@@ -1,4 +1,4 @@
-# Copyright 2022 VyOS maintainers and contributors <maintainers@vyos.io>
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -14,3 +14,5 @@
 # License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
 __all_: list[str] = ['disk', 'grub', 'image']
+# define image-tools version
+SYSTEM_CFG_VER = 1
diff --git a/python/vyos/system/compat.py b/python/vyos/system/compat.py
new file mode 100644
index 000000000..aa9b0b4b5
--- /dev/null
+++ b/python/vyos/system/compat.py
@@ -0,0 +1,307 @@
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+from pathlib import Path
+from re import compile, MULTILINE, DOTALL
+from functools import wraps
+from copy import deepcopy
+from typing import Union
+
+from vyos.system import disk, grub, image, SYSTEM_CFG_VER
+from vyos.template import render
+
+TMPL_GRUB_COMPAT: str = 'grub/grub_compat.j2'
+
+# define regexes and variables
+REGEX_VERSION = r'^menuentry "[^\n]*{\n[^}]*\s+linux /boot/(?P<version>\S+)/[^}]*}'
+REGEX_MENUENTRY = r'^menuentry "[^\n]*{\n[^}]*\s+linux /boot/(?P<version>\S+)/vmlinuz (?P<options>[^\n]+)\n[^}]*}'
+REGEX_CONSOLE = r'^.*console=(?P<console_type>[^\s\d]+)(?P<console_num>[\d]+).*$'
+REGEX_SANIT_CONSOLE = r'\ ?console=[^\s\d]+[\d]+(,\d+)?\ ?'
+REGEX_SANIT_INIT = r'\ ?init=\S*\ ?'
+REGEX_SANIT_QUIET = r'\ ?quiet\ ?'
+PW_RESET_OPTION = 'init=/opt/vyatta/sbin/standalone_root_pw_reset'
+
+
+class DowngradingImageTools(Exception):
+    """Raised when attempting to add an image with an earlier version
+    of image-tools than the current system, as indicated by the value
+    of SYSTEM_CFG_VER or absence thereof."""
+    pass
+
+
+def mode():
+    if grub.get_cfg_ver() >= SYSTEM_CFG_VER:
+        return False
+
+    return True
+
+
+def find_versions(menu_entries: list) -> list:
+    """Find unique VyOS versions from menu entries
+
+    Args:
+        menu_entries (list): a list with menu entries
+
+    Returns:
+        list: List of installed versions
+    """
+    versions = []
+    for vyos_ver in menu_entries:
+        versions.append(vyos_ver.get('version'))
+    # remove duplicates
+    versions = list(set(versions))
+    return versions
+
+
+def filter_unparsed(grub_path: str) -> str:
+    """Find currently installed VyOS version
+
+    Args:
+        grub_path (str): a path to the grub.cfg file
+
+    Returns:
+        str: unparsed grub.cfg items
+    """
+    config_text = Path(grub_path).read_text()
+    regex_filter = compile(REGEX_VERSION, MULTILINE | DOTALL)
+    filtered = regex_filter.sub('', config_text)
+    regex_filter = compile(grub.REGEX_GRUB_VARS, MULTILINE)
+    filtered = regex_filter.sub('', filtered)
+    regex_filter = compile(grub.REGEX_GRUB_MODULES, MULTILINE)
+    filtered = regex_filter.sub('', filtered)
+    # strip extra new lines
+    filtered = filtered.strip()
+    return filtered
+
+
+def sanitize_boot_opts(boot_opts: str) -> str:
+    """Sanitize boot options from console and init
+
+    Args:
+        boot_opts (str): boot options
+
+    Returns:
+        str: sanitized boot options
+    """
+    regex_filter = compile(REGEX_SANIT_CONSOLE)
+    boot_opts = regex_filter.sub('', boot_opts)
+    regex_filter = compile(REGEX_SANIT_INIT)
+    boot_opts = regex_filter.sub('', boot_opts)
+    # legacy tools add 'quiet' on add system image; this is not desired
+    regex_filter = compile(REGEX_SANIT_QUIET)
+    boot_opts = regex_filter.sub(' ', boot_opts)
+
+    return boot_opts
+
+
+def parse_entry(entry: tuple) -> dict:
+    """Parse GRUB menuentry
+
+    Args:
+        entry (tuple): tuple of (version, options)
+
+    Returns:
+        dict: dictionary with parsed options
+    """
+    # save version to dict
+    entry_dict = {'version': entry[0]}
+    # detect boot mode type
+    if PW_RESET_OPTION in entry[1]:
+        entry_dict['bootmode'] = 'pw_reset'
+    else:
+        entry_dict['bootmode'] = 'normal'
+    # find console type and number
+    regex_filter = compile(REGEX_CONSOLE)
+    entry_dict.update(regex_filter.match(entry[1]).groupdict())
+    entry_dict['boot_opts'] = sanitize_boot_opts(entry[1])
+
+    return entry_dict
+
+
+def parse_menuentries(grub_path: str) -> list:
+    """Parse all GRUB menuentries
+
+    Args:
+        grub_path (str): a path to GRUB config file
+
+    Returns:
+        list: list with menu items (each item is a dict)
+    """
+    menuentries = []
+    # read configuration file
+    config_text = Path(grub_path).read_text()
+    # parse menuentries to tuples (version, options)
+    regex_filter = compile(REGEX_MENUENTRY, MULTILINE)
+    filter_results = regex_filter.findall(config_text)
+    # parse each entry
+    for entry in filter_results:
+        menuentries.append(parse_entry(entry))
+
+    return menuentries
+
+
+def prune_vyos_versions(root_dir: str = '') -> None:
+    """Delete vyos-versions files of registered images subsequently deleted
+    or renamed by legacy image-tools
+
+    Args:
+        root_dir (str): an optional path to the root directory
+    """
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
+    for version in grub.version_list():
+        if not Path(f'{root_dir}/boot/{version}').is_dir():
+            grub.version_del(version)
+
+
+def update_cfg_ver(root_dir:str = '') -> int:
+    """Get minumum version of image-tools across all installed images
+
+    Args:
+        root_dir (str): an optional path to the root directory
+
+    Returns:
+        int: minimum version of image-tools
+    """
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
+    prune_vyos_versions(root_dir)
+
+    images_details = image.get_images_details()
+    cfg_version = min(d['tools_version'] for d in images_details)
+
+    return cfg_version
+
+
+def get_default(menu_entries: list, root_dir: str = '') -> Union[int, None]:
+    """Translate default version to menuentry index
+
+    Args:
+        menu_entries (list): list of dicts of installed version boot data
+        root_dir (str): an optional path to the root directory
+
+    Returns:
+        int: index of default version in menu_entries or None
+    """
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
+    grub_cfg_main = f'{root_dir}/{grub.GRUB_CFG_MAIN}'
+
+    image_name = image.get_default_image()
+
+    sublist = list(filter(lambda x: x.get('version') == image_name,
+                        menu_entries))
+    if sublist:
+        return menu_entries.index(sublist[0])
+
+    return None
+
+
+def update_version_list(root_dir: str = '') -> list[dict]:
+    """Update list of dicts of installed version boot data
+
+    Args:
+        root_dir (str): an optional path to the root directory
+
+    Returns:
+        list: list of dicts of installed version boot data
+    """
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
+    grub_cfg_main = f'{root_dir}/{grub.GRUB_CFG_MAIN}'
+
+    # get list of versions in menuentries
+    menu_entries = parse_menuentries(grub_cfg_main)
+    menu_versions = find_versions(menu_entries)
+
+    # get list of versions added/removed by image-tools
+    current_versions = grub.version_list(root_dir)
+
+    remove = list(set(menu_versions) - set(current_versions))
+    for ver in remove:
+        menu_entries = list(filter(lambda x: x.get('version') != ver,
+                                   menu_entries))
+
+    add = list(set(current_versions) - set(menu_versions))
+    for ver in add:
+        last = menu_entries[0].get('version')
+        new = deepcopy(list(filter(lambda x: x.get('version') == last,
+                                   menu_entries)))
+        for e in new:
+            boot_opts = e.get('boot_opts').replace(last, ver)
+            e.update({'version': ver, 'boot_opts': boot_opts})
+
+        menu_entries = new + menu_entries
+
+    return menu_entries
+
+
+def grub_cfg_fields(root_dir: str = '') -> dict:
+    """Gather fields for rendering grub.cfg
+
+    Args:
+        root_dir (str): an optional path to the root directory
+
+    Returns:
+        dict: dictionary for rendering TMPL_GRUB_COMPAT
+    """
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
+    grub_cfg_main = f'{root_dir}/{grub.GRUB_CFG_MAIN}'
+
+    fields = {'default': 0, 'timeout': 5}
+    # 'default' and 'timeout' from legacy grub.cfg
+    fields |= grub.vars_read(grub_cfg_main)
+    fields['tools_version'] = SYSTEM_CFG_VER
+    menu_entries = update_version_list(root_dir)
+    fields['versions'] = menu_entries
+    default = get_default(menu_entries, root_dir)
+    if default is not None:
+        fields['default'] = default
+
+    p = Path('/sys/firmware/efi')
+    if p.is_dir():
+        fields['efi'] = True
+    else:
+        fields['efi'] = False
+
+    return fields
+
+
+def render_grub_cfg(root_dir: str = '') -> None:
+    """Render grub.cfg for legacy compatibility"""
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
+    grub_cfg_main = f'{root_dir}/{grub.GRUB_CFG_MAIN}'
+
+    fields = grub_cfg_fields(root_dir)
+    render(grub_cfg_main, TMPL_GRUB_COMPAT, fields)
+
+
+def grub_cfg_update(func):
+    """Decorator to update grub.cfg after function call"""
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        ret = func(*args, **kwargs)
+        if mode():
+            render_grub_cfg()
+        return ret
+    return wrapper
diff --git a/python/vyos/system/disk.py b/python/vyos/system/disk.py
index b78190c06..882b4eb39 100644
--- a/python/vyos/system/disk.py
+++ b/python/vyos/system/disk.py
@@ -1,4 +1,4 @@
-# Copyright 2022 VyOS maintainers and contributors <maintainers@vyos.io>
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
diff --git a/python/vyos/system/grub.py b/python/vyos/system/grub.py
index 47c674de8..9ac205c03 100644
--- a/python/vyos/system/grub.py
+++ b/python/vyos/system/grub.py
@@ -1,4 +1,4 @@
-# Copyright 2022 VyOS maintainers and contributors <maintainers@vyos.io>
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -24,6 +24,7 @@ from vyos.system import disk
 
 # Define variables
 GRUB_DIR_MAIN: str = '/boot/grub'
+GRUB_CFG_MAIN: str = f'{GRUB_DIR_MAIN}/grub.cfg'
 GRUB_DIR_VYOS: str = f'{GRUB_DIR_MAIN}/grub.cfg.d'
 CFG_VYOS_HEADER: str = f'{GRUB_DIR_VYOS}/00-vyos-header.cfg'
 CFG_VYOS_MODULES: str = f'{GRUB_DIR_VYOS}/10-vyos-modules-autoload.cfg'
@@ -181,8 +182,8 @@ def get_cfg_ver(root_dir: str = '') -> int:
     if not root_dir:
         root_dir = disk.find_persistence()
 
-    cfg_ver: Union[str, None] = vars_read(f'{root_dir}/{CFG_VYOS_HEADER}').get(
-        'VYOS_CFG_VER')
+    cfg_ver: str = vars_read(f'{root_dir}/{CFG_VYOS_HEADER}').get(
+            'VYOS_CFG_VER')
     if cfg_ver:
         cfg_ver_int: int = int(cfg_ver)
     else:
diff --git a/python/vyos/system/image.py b/python/vyos/system/image.py
index b77c3563f..6c4e3bba5 100644
--- a/python/vyos/system/image.py
+++ b/python/vyos/system/image.py
@@ -1,4 +1,4 @@
-# Copyright 2022 VyOS maintainers and contributors <maintainers@vyos.io>
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -28,12 +28,14 @@ CFG_VYOS_VARS: str = f'{GRUB_DIR_VYOS}/20-vyos-defaults-autoload.cfg'
 GRUB_DIR_VYOS_VERS: str = f'{GRUB_DIR_VYOS}/vyos-versions'
 # prepare regexes
 REGEX_KERNEL_CMDLINE: str = r'^BOOT_IMAGE=/(?P<boot_type>boot|live)/((?P<image_version>.+)/)?vmlinuz.*$'
+REGEX_SYSTEM_CFG_VER: str = r'(\r\n|\r|\n)SYSTEM_CFG_VER\s*=\s*(?P<cfg_ver>\d+)(\r\n|\r|\n)'
 
 
 # structures definitions
 class ImageDetails(TypedDict):
     name: str
     version: str
+    tools_version: int
     disk_ro: int
     disk_rw: int
     disk_total: int
@@ -59,26 +61,73 @@ def bootmode_detect() -> str:
         return 'bios'
 
 
-def get_version(image_name: str, root_dir: str) -> str:
-    """Extract version name from rootfs based on image name
+def get_image_version(mount_path: str) -> str:
+    """Extract version name from rootfs mounted at mount_path
 
     Args:
-        image_name (str): a name of image (from boot menu)
-        root_dir (str): a root directory of persistence storage
+        mount_path (str): mount path of rootfs
 
     Returns:
         str: version name
     """
+    version_file: str = Path(
+        f'{mount_path}/opt/vyatta/etc/version').read_text()
+    version_name: str = version_file.lstrip('Version: ').strip()
+
+    return version_name
+
+
+def get_image_tools_version(mount_path: str) -> int:
+    """Extract image-tools version from rootfs mounted at mount_path
+
+    Args:
+        mount_path (str): mount path of rootfs
+
+    Returns:
+        str: image-tools version
+    """
+    try:
+        version_file: str = Path(
+            f'{mount_path}/usr/lib/python3/dist-packages/vyos/system/__init__.py').read_text()
+    except FileNotFoundError:
+        system_cfg_ver: int = 0
+    else:
+        res = re_compile(REGEX_SYSTEM_CFG_VER).search(version_file)
+        system_cfg_ver: int = int(res.groupdict().get('cfg_ver', 0))
+
+    return system_cfg_ver
+
+
+def get_versions(image_name: str, root_dir: str = '') -> dict[str, str]:
+    """Return versions of image and image-tools
+
+    Args:
+        image_name (str): a name of an image
+        root_dir (str, optional): an optional path to the root directory.
+        Defaults to ''.
+
+    Returns:
+        dict[str, int]: a dictionary with versions of image and image-tools
+    """
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
     squashfs_file: str = next(
         Path(f'{root_dir}/boot/{image_name}').glob('*.squashfs')).as_posix()
     with TemporaryDirectory() as squashfs_mounted:
         disk.partition_mount(squashfs_file, squashfs_mounted, 'squashfs')
-        version_file: str = Path(
-            f'{squashfs_mounted}/opt/vyatta/etc/version').read_text()
+
+        image_version: str = get_image_version(squashfs_mounted)
+        image_tools_version: int = get_image_tools_version(squashfs_mounted)
+
         disk.partition_umount(squashfs_file)
-        version_name: str = version_file.lstrip('Version: ').strip()
 
-    return version_name
+    versions: dict[str, int] = {
+        'image': image_version,
+        'image-tools': image_tools_version
+    }
+
+    return versions
 
 
 def get_details(image_name: str, root_dir: str = '') -> ImageDetails:
@@ -95,7 +144,9 @@ def get_details(image_name: str, root_dir: str = '') -> ImageDetails:
     if not root_dir:
         root_dir = disk.find_persistence()
 
-    image_version: str = get_version(image_name, root_dir)
+    versions = get_versions(image_name, root_dir)
+    image_version: str = versions.get('image', '')
+    image_tools_version: int = versions.get('image-tools', 0)
 
     image_path: Path = Path(f'{root_dir}/boot/{image_name}')
     image_path_rw: Path = Path(f'{root_dir}/boot/{image_name}/rw')
@@ -113,6 +164,7 @@ def get_details(image_name: str, root_dir: str = '') -> ImageDetails:
     image_details: ImageDetails = {
         'name': image_name,
         'version': image_version,
+        'tools_version': image_tools_version,
         'disk_ro': image_disk_ro,
         'disk_rw': image_disk_rw,
         'disk_total': image_disk_ro + image_disk_rw
@@ -121,6 +173,20 @@ def get_details(image_name: str, root_dir: str = '') -> ImageDetails:
     return image_details
 
 
+def get_images_details() -> list[ImageDetails]:
+    """Return information about all images
+
+    Returns:
+        list[ImageDetails]: a list of dictionaries with details about images
+    """
+    images: list[str] = grub.version_list()
+    images_details: list[ImageDetails] = list()
+    for image_name in images:
+        images_details.append(get_details(image_name))
+
+    return images_details
+
+
 def get_running_image() -> str:
     """Find currently running image name
 
@@ -134,7 +200,7 @@ def get_running_image() -> str:
     if running_image_result:
         running_image: str = running_image_result.groupdict().get(
             'image_version', '')
-    # we need to have a fallbak for live systems
+    # we need to have a fallback for live systems
     if not running_image:
         running_image: str = version.get_version()
 
diff --git a/src/op_mode/image_info.py b/src/op_mode/image_info.py
index 14dca7476..791001e00 100755
--- a/src/op_mode/image_info.py
+++ b/src/op_mode/image_info.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright 2022 VyOS maintainers and contributors <maintainers@vyos.io>
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
 #
 # This file is part of VyOS.
 #
@@ -91,10 +91,7 @@ def show_images_summary(raw: bool) -> Union[image.BootDetails, str]:
 
 
 def show_images_details(raw: bool) -> Union[list[image.ImageDetails], str]:
-    images: list[str] = grub.version_list()
-    images_details: list[image.ImageDetails] = list()
-    for image_name in images:
-        images_details.append(image.get_details(image_name))
+    images_details = image.get_images_details()
 
     if raw:
         return images_details
diff --git a/src/op_mode/image_installer.py b/src/op_mode/image_installer.py
index 12d32968c..2d998f5e1 100755
--- a/src/op_mode/image_installer.py
+++ b/src/op_mode/image_installer.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright 2022 VyOS maintainers and contributors <maintainers@vyos.io>
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
 #
 # This file is part of VyOS.
 #
@@ -28,7 +28,7 @@ from psutil import disk_partitions
 
 from vyos.configtree import ConfigTree
 from vyos.remote import download
-from vyos.system import disk, grub, image
+from vyos.system import disk, grub, image, compat, SYSTEM_CFG_VER
 from vyos.template import render
 from vyos.utils.io import ask_input, ask_yes_no
 from vyos.utils.file import chmod_2775
@@ -462,6 +462,7 @@ def install_image() -> None:
         exit(1)
 
 
+@compat.grub_cfg_update
 def add_image(image_path: str) -> None:
     """Add a new image
 
@@ -488,10 +489,16 @@ def add_image(image_path: str) -> None:
         Path(DIR_ROOTFS_SRC).mkdir(mode=0o755, parents=True)
         disk.partition_mount(f'{DIR_ISO_MOUNT}/live/filesystem.squashfs',
                              DIR_ROOTFS_SRC, 'squashfs')
-        version_file: str = Path(
-            f'{DIR_ROOTFS_SRC}/opt/vyatta/etc/version').read_text()
+
+        cfg_ver: str = image.get_image_tools_version(DIR_ROOTFS_SRC)
+        version_name: str = image.get_image_version(DIR_ROOTFS_SRC)
+
         disk.partition_umount(f'{DIR_ISO_MOUNT}/live/filesystem.squashfs')
-        version_name: str = version_file.lstrip('Version: ').strip()
+
+        if cfg_ver < SYSTEM_CFG_VER:
+            raise compat.DowngradingImageTools(
+                f'Adding image would downgrade image tools to v.{cfg_ver}; disallowed')
+
         image_name: str = ask_input(MSG_INPUT_IMAGE_NAME, version_name)
         set_as_default: bool = ask_yes_no(MSG_INPUT_IMAGE_DEFAULT, default=True)
 
diff --git a/src/op_mode/image_manager.py b/src/op_mode/image_manager.py
index 76fc4367f..725c40613 100755
--- a/src/op_mode/image_manager.py
+++ b/src/op_mode/image_manager.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright 2022 VyOS maintainers and contributors <maintainers@vyos.io>
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
 #
 # This file is part of VyOS.
 #
@@ -22,10 +22,11 @@ from pathlib import Path
 from shutil import rmtree
 from sys import exit
 
-from vyos.system import disk, grub, image
+from vyos.system import disk, grub, image, compat
 from vyos.utils.io import ask_yes_no
 
 
+@compat.grub_cfg_update
 def delete_image(image_name: str) -> None:
     """Remove installed image files and boot entry
 
@@ -57,6 +58,7 @@ def delete_image(image_name: str) -> None:
         exit(f'Unable to remove the image "{image_name}": {err}')
 
 
+@compat.grub_cfg_update
 def set_image(image_name: str) -> None:
     """Set default boot image
 
@@ -86,6 +88,7 @@ def set_image(image_name: str) -> None:
         exit(f'Unable to set default image "{image_name}": {err}')
 
 
+@compat.grub_cfg_update
 def rename_image(name_old: str, name_new: str) -> None:
     """Rename installed image
 
diff --git a/src/system/grub_update.py b/src/system/grub_update.py
index 1ae66464b..da1986e9d 100644
--- a/src/system/grub_update.py
+++ b/src/system/grub_update.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright 2022 VyOS maintainers and contributors <maintainers@vyos.io>
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
 #
 # This file is part of VyOS.
 #
@@ -18,23 +18,11 @@
 # VyOS. If not, see <https://www.gnu.org/licenses/>.
 
 from pathlib import Path
-from re import compile, MULTILINE, DOTALL
 from sys import exit
 
-from vyos.system import disk, grub, image
+from vyos.system import disk, grub, image, compat, SYSTEM_CFG_VER
 from vyos.template import render
 
-# define configuration version
-CFG_VER = 1
-
-# define regexes and variables
-REGEX_VERSION = r'^menuentry "[^\n]*{\n[^}]*\s+linux /boot/(?P<version>\S+)/[^}]*}'
-REGEX_MENUENTRY = r'^menuentry "[^\n]*{\n[^}]*\s+linux /boot/(?P<version>\S+)/vmlinuz (?P<options>[^\n]+)\n[^}]*}'
-REGEX_CONSOLE = r'^.*console=(?P<console_type>[^\s\d]+)(?P<console_num>[\d]+).*$'
-REGEX_SANIT_CONSOLE = r'\ ?console=[^\s\d]+[\d]+(,\d+)?\ ?'
-REGEX_SANIT_INIT = r'\ ?init=\S*\ ?'
-PW_RESET_OPTION = 'init=/opt/vyatta/sbin/standalone_root_pw_reset'
-
 
 def cfg_check_update() -> bool:
     """Check if GRUB structure update is required
@@ -43,111 +31,10 @@ def cfg_check_update() -> bool:
         bool: False if not required, True if required
     """
     current_ver = grub.get_cfg_ver()
-    if current_ver and current_ver >= CFG_VER:
+    if current_ver and current_ver >= SYSTEM_CFG_VER:
         return False
-    else:
-        return True
-
-
-def find_versions(menu_entries: list) -> list:
-    """Find unique VyOS versions from menu entries
-
-    Args:
-        menu_entries (list): a list with menu entries
-
-    Returns:
-        list: List of installed versions
-    """
-    versions = []
-    for vyos_ver in menu_entries:
-        versions.append(vyos_ver.get('version'))
-    # remove duplicates
-    versions = list(set(versions))
-    return versions
-
 
-def filter_unparsed(grub_path: str) -> str:
-    """Find currently installed VyOS version
-
-    Args:
-        grub_path (str): a path to the grub.cfg file
-
-    Returns:
-        str: unparsed grub.cfg items
-    """
-    config_text = Path(grub_path).read_text()
-    regex_filter = compile(REGEX_VERSION, MULTILINE | DOTALL)
-    filtered = regex_filter.sub('', config_text)
-    regex_filter = compile(grub.REGEX_GRUB_VARS, MULTILINE)
-    filtered = regex_filter.sub('', filtered)
-    regex_filter = compile(grub.REGEX_GRUB_MODULES, MULTILINE)
-    filtered = regex_filter.sub('', filtered)
-    # strip extra new lines
-    filtered = filtered.strip()
-    return filtered
-
-
-def sanitize_boot_opts(boot_opts: str) -> str:
-    """Sanitize boot options from console and init
-
-    Args:
-        boot_opts (str): boot options
-
-    Returns:
-        str: sanitized boot options
-    """
-    regex_filter = compile(REGEX_SANIT_CONSOLE)
-    boot_opts = regex_filter.sub('', boot_opts)
-    regex_filter = compile(REGEX_SANIT_INIT)
-    boot_opts = regex_filter.sub('', boot_opts)
-
-    return boot_opts
-
-
-def parse_entry(entry: tuple) -> dict:
-    """Parse GRUB menuentry
-
-    Args:
-        entry (tuple): tuple of (version, options)
-
-    Returns:
-        dict: dictionary with parsed options
-    """
-    # save version to dict
-    entry_dict = {'version': entry[0]}
-    # detect boot mode type
-    if PW_RESET_OPTION in entry[1]:
-        entry_dict['bootmode'] = 'pw_reset'
-    else:
-        entry_dict['bootmode'] = 'normal'
-    # find console type and number
-    regex_filter = compile(REGEX_CONSOLE)
-    entry_dict.update(regex_filter.match(entry[1]).groupdict())
-    entry_dict['boot_opts'] = sanitize_boot_opts(entry[1])
-
-    return entry_dict
-
-
-def parse_menuntries(grub_path: str) -> list:
-    """Parse all GRUB menuentries
-
-    Args:
-        grub_path (str): a path to GRUB config file
-
-    Returns:
-        list: list with menu items (each item is a dict)
-    """
-    menuentries = []
-    # read configuration file
-    config_text = Path(grub_path).read_text()
-    # parse menuentries to tuples (version, options)
-    regex_filter = compile(REGEX_MENUENTRY, MULTILINE)
-    filter_results = regex_filter.findall(config_text)
-    # parse each entry
-    for entry in filter_results:
-        menuentries.append(parse_entry(entry))
-
-    return menuentries
+    return True
 
 
 if __name__ == '__main__':
@@ -162,12 +49,12 @@ if __name__ == '__main__':
     root_dir = disk.find_persistence()
 
     # read current GRUB config
-    grub_cfg_main = f'{root_dir}/{image.GRUB_DIR_MAIN}/grub.cfg'
+    grub_cfg_main = f'{root_dir}/{grub.GRUB_CFG_MAIN}'
     vars = grub.vars_read(grub_cfg_main)
     modules = grub.modules_read(grub_cfg_main)
-    vyos_menuentries = parse_menuntries(grub_cfg_main)
-    vyos_versions = find_versions(vyos_menuentries)
-    unparsed_items = filter_unparsed(grub_cfg_main)
+    vyos_menuentries = compat.parse_menuentries(grub_cfg_main)
+    vyos_versions = compat.find_versions(vyos_menuentries)
+    unparsed_items = compat.filter_unparsed(grub_cfg_main)
 
     # find default values
     default_entry = vyos_menuentries[int(vars['default'])]
@@ -185,13 +72,12 @@ if __name__ == '__main__':
     # print(f'unparsed_items: {unparsed_items}')
 
     # create new files
-    grub_cfg_vars = f'{root_dir}/{image.CFG_VYOS_VARS}'
+    grub_cfg_vars = f'{root_dir}/{grub.CFG_VYOS_VARS}'
     grub_cfg_modules = f'{root_dir}/{grub.CFG_VYOS_MODULES}'
     grub_cfg_platform = f'{root_dir}/{grub.CFG_VYOS_PLATFORM}'
     grub_cfg_menu = f'{root_dir}/{grub.CFG_VYOS_MENU}'
     grub_cfg_options = f'{root_dir}/{grub.CFG_VYOS_OPTIONS}'
 
-    render(grub_cfg_main, grub.TMPL_GRUB_MAIN, {})
     Path(image.GRUB_DIR_VYOS).mkdir(exist_ok=True)
     grub.vars_write(grub_cfg_vars, vars)
     grub.modules_write(grub_cfg_modules, modules)
@@ -210,5 +96,12 @@ if __name__ == '__main__':
         grub.version_add(vyos_ver, root_dir, boot_opts)
 
     # update structure version
-    grub.write_cfg_ver(CFG_VER, root_dir)
+    cfg_ver = compat.update_cfg_ver(root_dir)
+    grub.write_cfg_ver(cfg_ver, root_dir)
+
+    if compat.mode():
+        compat.render_grub_cfg(root_dir)
+    else:
+        render(grub_cfg_main, grub.TMPL_GRUB_MAIN, {})
+
     exit(0)