nova/nova/virt/images.py
2015-03-04 01:24:45 +00:00

137 lines
5.0 KiB
Python

# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
# Copyright (c) 2010 Citrix Systems, Inc.
#
# 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.
"""
Handling of VM disk images.
"""
import os
from oslo_config import cfg
from oslo_log import log as logging
from nova import exception
from nova.i18n import _, _LE
from nova import image
from nova.openstack.common import fileutils
from nova.openstack.common import imageutils
from nova import utils
LOG = logging.getLogger(__name__)
image_opts = [
cfg.BoolOpt('force_raw_images',
default=True,
help='Force backing images to raw format'),
]
CONF = cfg.CONF
CONF.register_opts(image_opts)
IMAGE_API = image.API()
def qemu_img_info(path):
"""Return an object containing the parsed output from qemu-img info."""
# TODO(mikal): this code should not be referring to a libvirt specific
# flag.
# NOTE(sirp): The config option import must go here to avoid an import
# cycle
CONF.import_opt('images_type', 'nova.virt.libvirt.imagebackend',
group='libvirt')
if not os.path.exists(path) and CONF.libvirt.images_type != 'rbd':
msg = (_("Path does not exist %(path)s") % {'path': path})
raise exception.InvalidDiskInfo(reason=msg)
out, err = utils.execute('env', 'LC_ALL=C', 'LANG=C',
'qemu-img', 'info', path)
if not out:
msg = (_("Failed to run qemu-img info on %(path)s : %(error)s") %
{'path': path, 'error': err})
raise exception.InvalidDiskInfo(reason=msg)
return imageutils.QemuImgInfo(out)
def convert_image(source, dest, out_format, run_as_root=False):
"""Convert image to other format."""
cmd = ('qemu-img', 'convert', '-O', out_format, source, dest)
utils.execute(*cmd, run_as_root=run_as_root)
def fetch(context, image_href, path, _user_id, _project_id, max_size=0):
with fileutils.remove_path_on_error(path):
IMAGE_API.download(context, image_href, dest_path=path)
def get_info(context, image_href):
return IMAGE_API.get(context, image_href)
def fetch_to_raw(context, image_href, path, user_id, project_id, max_size=0):
path_tmp = "%s.part" % path
fetch(context, image_href, path_tmp, user_id, project_id,
max_size=max_size)
with fileutils.remove_path_on_error(path_tmp):
data = qemu_img_info(path_tmp)
fmt = data.file_format
if fmt is None:
raise exception.ImageUnacceptable(
reason=_("'qemu-img info' parsing failed."),
image_id=image_href)
backing_file = data.backing_file
if backing_file is not None:
raise exception.ImageUnacceptable(image_id=image_href,
reason=(_("fmt=%(fmt)s backed by: %(backing_file)s") %
{'fmt': fmt, 'backing_file': backing_file}))
# We can't generally shrink incoming images, so disallow
# images > size of the flavor we're booting. Checking here avoids
# an immediate DoS where we convert large qcow images to raw
# (which may compress well but not be sparse).
# TODO(p-draigbrady): loop through all flavor sizes, so that
# we might continue here and not discard the download.
# If we did that we'd have to do the higher level size checks
# irrespective of whether the base image was prepared or not.
disk_size = data.virtual_size
if max_size and max_size < disk_size:
LOG.error(_LE('%(base)s virtual size %(disk_size)s '
'larger than flavor root disk size %(size)s'),
{'base': path,
'disk_size': disk_size,
'size': max_size})
raise exception.FlavorDiskTooSmall()
if fmt != "raw" and CONF.force_raw_images:
staged = "%s.converted" % path
LOG.debug("%s was %s, converting to raw" % (image_href, fmt))
with fileutils.remove_path_on_error(staged):
convert_image(path_tmp, staged, 'raw')
os.unlink(path_tmp)
data = qemu_img_info(staged)
if data.file_format != "raw":
raise exception.ImageUnacceptable(image_id=image_href,
reason=_("Converted to raw, but format is now %s") %
data.file_format)
os.rename(staged, path)
else:
os.rename(path_tmp, path)