#!/usr/bin/env python
#
# vm_factory.py - Factory for virtual machine objects
#
# December 2014, Glenn F. Matthews
# Copyright (c) 2013-2016 the COT project developers.
# See the COPYRIGHT.txt file at the top-level directory of this distribution
# and at https://github.com/glennmatthews/cot/blob/master/COPYRIGHT.txt.
#
# This file is part of the Common OVF Tool (COT) project.
# It is subject to the license terms in the LICENSE.txt file found in the
# top-level directory of this distribution and at
# https://github.com/glennmatthews/cot/blob/master/LICENSE.txt. No part
# of COT, including this file, may be copied, modified, propagated, or
# distributed except according to the terms contained in the LICENSE.txt file.
"""Factory for virtual machine objects."""
import logging
from .ovf import OVF
from .vm_description import VMInitError
from .data_validation import ValueUnsupportedError
logger = logging.getLogger(__name__)
[docs]class VMFactory(object):
"""Creates a VMDescription instance from a specified input file."""
@classmethod
[docs] def create(cls, input_file, output_file):
"""Create an appropriate VMDescription subclass instance from a file.
Args:
input_file (str): File to read VM description from
output_file (str): File to write to when finished (optional)
Raises:
VMInitError: if no appropriate class is identified
VMInitError: if the selected subclass raises a
ValueUnsupportedError while loading the file.
Returns:
VMDescription: Created object
"""
vm_class = None
supported_types = []
# Add other VMDescription subclasses as needed
for candidate_class in [OVF]:
try:
candidate_class.detect_type_from_name(input_file)
vm_class = candidate_class
break
except ValueUnsupportedError as e:
supported_types += [e.expected_value]
if not vm_class:
raise VMInitError(2,
"Unknown VM description type for input file - "
"only supported types are {0}"
.format(supported_types),
input_file)
logger.info("Loading '%s' as %s", input_file, vm_class.__name__)
try:
vm = vm_class(input_file, output_file)
except ValueUnsupportedError as e:
raise VMInitError(2, str(e), input_file)
logger.debug("Loaded VM object from %s", input_file)
return vm