cachemonkey/cachemonkey/cacher.py

68 lines
2.2 KiB
Python

# Copyright 2014 Rackspace Hosting
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import os
from oslo.config import cfg
from cachemonkey.openstack.common import importutils
from cachemonkey.openstack.common import log as logging
LOG = logging.getLogger(__name__)
CONF = cfg.CONF
opts = [
cfg.StrOpt('lister_class',
default='cachemonkey.lister.glance.GlanceLister',
help='Class to determine which images get pre-cached'),
cfg.StrOpt('fetcher_class',
default='cachemonkey.fetcher.glance.GlanceFetcher',
help='Class to determine how to fetch images.'),
cfg.StrOpt('data_dir', default='/var/lib/cachemonkey',
help='Directory containing image data'),
]
CONF.register_opts(opts, group='cachemonkey')
class Cacher(object):
def __init__(self):
self.lister = importutils.import_object(CONF.cachemonkey.lister_class)
self.fetcher = importutils.import_object(
CONF.cachemonkey.fetcher_class)
def cache(self):
images = self.lister.images()
for image in images:
self._get(image)
# TODO(belliott) distribute to hosts
def _get(self, image):
# first see if the image was previously downloaded
d = os.path.join(CONF.cachemonkey.data_dir)
if not os.path.exists(d):
os.makedirs(d)
filename = os.path.join(d, image['id'])
if os.path.exists(filename):
LOG.debug("Image %s was previously downloaded." % image['id'])
# TODO(belliott) also verify checksum
else:
self.fetcher.fetch(image, filename)
return filename