cloud-init/cloudinit/importer.py
Joshua Harlow 47360ed843 1. Add an importer function that will search for a given module in a set of search module 'prefixes'
that also has a potential set of required attributes.
2. Use this new importer to find the distro class, the userdata handler modules, the config modules
   and the datasource modules, if none can be found error out accordingly.
2012-06-20 23:40:00 -07:00

66 lines
2.1 KiB
Python

# vi: ts=4 expandtab
#
# Copyright (C) 2012 Canonical Ltd.
# Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
# Copyright (C) 2012 Yahoo! Inc.
#
# Author: Scott Moser <scott.moser@canonical.com>
# Author: Juerg Haefliger <juerg.haefliger@hp.com>
# Author: Joshua Harlow <harlowja@yahoo-inc.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 3, as
# published by the Free Software Foundation.
#
# This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
import sys
from cloudinit import log as logging
LOG = logging.getLogger(__name__)
def import_module(module_name):
__import__(module_name)
return sys.modules[module_name]
def find_module(base_name, search_paths, required_attrs=None):
found_places = []
if not required_attrs:
required_attrs = []
real_paths = []
for path in search_paths:
real_path = []
if path:
real_path.extend(path.split("."))
real_path.append(base_name)
full_path = '.'.join(real_path)
real_paths.append(full_path)
LOG.debug("Looking for modules %s that have attributes %s",
real_paths, required_attrs)
for full_path in real_paths:
mod = None
try:
mod = import_module(full_path)
except ImportError:
pass
if not mod:
continue
found_attrs = 0
for attr in required_attrs:
if hasattr(mod, attr):
found_attrs += 1
if found_attrs == len(required_attrs):
found_places.append(full_path)
LOG.debug("Found %s with attributes %s in %s", base_name,
required_attrs, found_places)
return found_places