From 7e4caa118692d9b6fd798783596bd018f805e5eb Mon Sep 17 00:00:00 2001 From: John Estabrook Date: Sun, 10 Dec 2023 15:27:35 -0600 Subject: load-config: T5815: provide a variety of load config methods Collect in a module several versions of a 'load config' function. They have different use cases according to performance and error reporting, and allow comparison of non-legacy and legacy variants. --- python/vyos/load_config.py | 200 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 200 insertions(+) create mode 100644 python/vyos/load_config.py (limited to 'python/vyos/load_config.py') diff --git a/python/vyos/load_config.py b/python/vyos/load_config.py new file mode 100644 index 000000000..af563614d --- /dev/null +++ b/python/vyos/load_config.py @@ -0,0 +1,200 @@ +# Copyright 2023 VyOS maintainers and contributors +# +# 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 . + +"""This module abstracts the loading of a config file into the running +config. It provides several varieties of loading a config file, from the +legacy version to the developing versions, as a means of offering +alternatives for competing use cases, and a base for profiling the +performance of each. +""" + +import sys +from pathlib import Path +from tempfile import NamedTemporaryFile +from typing import Union, Literal, TypeAlias, get_type_hints, get_args + +from vyos.config import Config +from vyos.configtree import ConfigTree, DiffTree +from vyos.configsource import ConfigSourceSession, VyOSError +from vyos.component_version import from_string as version_from_string +from vyos.component_version import from_system as version_from_system +from vyos.migrator import Migrator, VirtualMigrator, MigratorError +from vyos.utils.process import popen, DEVNULL + +Variety: TypeAlias = Literal['explicit', 'batch', 'tree', 'legacy'] +ConfigObj: TypeAlias = Union[str, ConfigTree] + +thismod = sys.modules[__name__] + +class LoadConfigError(Exception): + """Raised when an error occurs loading a config file. + """ + +# utility functions + +def get_running_config(config: Config) -> ConfigTree: + return config.get_config_tree(effective=True) + +def get_proposed_config(config_file: str = None) -> ConfigTree: + config_str = Path(config_file).read_text() + return ConfigTree(config_str) + +def migration_needed(config_obj: ConfigObj) -> bool: + """Check if a migration is needed for the config object. + """ + if not isinstance(config_obj, ConfigTree): + atree = get_proposed_config(config_obj) + else: + atree = config_obj + version_str = atree.get_version_string() + if not version_str: + return True + aversion = version_from_string(version_str.splitlines()[1]) + bversion = version_from_system() + return aversion != bversion + +def check_session(strict: bool, switch: Variety) -> None: + """Check if we are in a config session, with no uncommitted changes, if + strict. This is not needed for legacy load, as these checks are + implicit. + """ + + if switch == 'legacy': + return + + context = ConfigSourceSession() + + if not context.in_session(): + raise LoadConfigError('not in a config session') + + if strict and context.session_changed(): + raise LoadConfigError('commit or discard changes before loading config') + +# methods to call for each variety + +# explicit +def diff_to_commands(ctree: ConfigTree, ntree: ConfigTree) -> list: + """Calculate the diff between the current and proposed config.""" + # Calculate the diff between the current and new config tree + commands = DiffTree(ctree, ntree).to_commands() + # on an empty set of 'add' or 'delete' commands, to_commands + # returns '\n'; prune below + command_list = commands.splitlines() + command_list = [c for c in command_list if c] + return command_list + +def set_commands(cmds: list) -> None: + """Set commands in the config session.""" + if not cmds: + print('no commands to set') + return + error_out = [] + for op in cmds: + out, rc = popen(f'/opt/vyatta/sbin/my_{op}', shell=True, stderr=DEVNULL) + if rc != 0: + error_out.append(out) + continue + if error_out: + out = '\n'.join(error_out) + raise LoadConfigError(out) + +# legacy +class LoadConfig(ConfigSourceSession): + """A subclass for calling 'loadFile'. + """ + def load_config(self, file_name): + return self._run(['/bin/cli-shell-api','loadFile', file_name]) + +# end methods to call for each variety + +def migrate(config_obj: ConfigObj) -> ConfigObj: + """Migrate a config object to the current version. + """ + if isinstance(config_obj, ConfigTree): + config_file = NamedTemporaryFile(delete=False).name + Path(config_file).write_text(config_obj.to_string()) + else: + config_file = config_obj + + virtual_migration = VirtualMigrator(config_file) + migration = Migrator(config_file) + try: + virtual_migration.run() + migration.run() + except MigratorError as e: + raise LoadConfigError(e) from e + else: + if isinstance(config_obj, ConfigTree): + return ConfigTree(Path(config_file).read_text()) + return config_file + finally: + if isinstance(config_obj, ConfigTree): + Path(config_file).unlink() + +def load_explicit(config_obj: ConfigObj): + """Explicit load from file or configtree. + """ + config = Config() + ctree = get_running_config(config) + if isinstance(config_obj, ConfigTree): + ntree = config_obj + else: + ntree = get_proposed_config(config_obj) + # Calculate the diff between the current and proposed config + cmds = diff_to_commands(ctree, ntree) + # Set the commands in the config session + set_commands(cmds) + +def load_batch(config_obj: ConfigObj): + # requires legacy backend patch + raise NotImplementedError('batch loading not implemented') + +def load_tree(config_obj: ConfigObj): + # requires vyconf backend patch + raise NotImplementedError('tree loading not implemented') + +def load_legacy(config_obj: ConfigObj): + """Legacy load from file or configtree. + """ + if isinstance(config_obj, ConfigTree): + config_file = NamedTemporaryFile(delete=False).name + Path(config_file).write_text(config_obj.to_string()) + else: + config_file = config_obj + + config = LoadConfig() + + try: + config.load_config(config_file) + except VyOSError as e: + raise LoadConfigError(e) from e + finally: + if isinstance(config_obj, ConfigTree): + Path(config_file).unlink() + +def load(config_obj: ConfigObj, strict: bool = True, + switch: Variety = 'legacy'): + type_hints = get_type_hints(load) + switch_choice = get_args(type_hints['switch']) + if switch not in switch_choice: + raise ValueError(f'invalid switch: {switch}') + + check_session(strict, switch) + + if migration_needed(config_obj): + config_obj = migrate(config_obj) + + func = getattr(thismod, f'load_{switch}') + func(config_obj) -- cgit v1.2.3