/
utils.py
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/
utils.py
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# 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.
# Copyright (c) 2011 Piston Cloud Computing, Inc
# Copyright (c) 2011 OpenStack Foundation
# (c) Copyright 2013 Hewlett-Packard Development Company, L.P.
#
# 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 errno
import os
import re
from lxml import etree
from oslo_concurrency import processutils
from oslo_log import log as logging
from nova.compute import arch
from nova.compute import vm_mode
import nova.conf
from nova.i18n import _
from nova.i18n import _LI
from nova import utils
from nova.virt import images
from nova.virt.libvirt import config as vconfig
from nova.virt.libvirt.volume import remotefs
from nova.virt import volumeutils
CONF = nova.conf.CONF
LOG = logging.getLogger(__name__)
RESIZE_SNAPSHOT_NAME = 'nova-resize'
def execute(*args, **kwargs):
return utils.execute(*args, **kwargs)
def get_iscsi_initiator():
return volumeutils.get_iscsi_initiator()
def create_image(disk_format, path, size):
"""Create a disk image
:param disk_format: Disk image format (as known by qemu-img)
:param path: Desired location of the disk image
:param size: Desired size of disk image. May be given as an int or
a string. If given as an int, it will be interpreted
as bytes. If it's a string, it should consist of a number
with an optional suffix ('K' for Kibibytes,
M for Mebibytes, 'G' for Gibibytes, 'T' for Tebibytes).
If no suffix is given, it will be interpreted as bytes.
"""
execute('qemu-img', 'create', '-f', disk_format, path, size)
def create_cow_image(backing_file, path, size=None):
"""Create COW image
Creates a COW image with the given backing file
:param backing_file: Existing image on which to base the COW image
:param path: Desired location of the COW image
"""
base_cmd = ['qemu-img', 'create', '-f', 'qcow2']
cow_opts = []
if backing_file:
cow_opts += ['backing_file=%s' % backing_file]
base_details = images.qemu_img_info(backing_file)
else:
base_details = None
# Explicitly inherit the value of 'cluster_size' property of a qcow2
# overlay image from its backing file. This can be useful in cases
# when people create a base image with a non-default 'cluster_size'
# value or cases when images were created with very old QEMU
# versions which had a different default 'cluster_size'.
if base_details and base_details.cluster_size is not None:
cow_opts += ['cluster_size=%s' % base_details.cluster_size]
if size is not None:
cow_opts += ['size=%s' % size]
if cow_opts:
# Format as a comma separated list
csv_opts = ",".join(cow_opts)
cow_opts = ['-o', csv_opts]
cmd = base_cmd + cow_opts + [path]
execute(*cmd)
def pick_disk_driver_name(hypervisor_version, is_block_dev=False):
"""Pick the libvirt primary backend driver name
If the hypervisor supports multiple backend drivers we have to tell libvirt
which one should be used.
Xen supports the following drivers: "tap", "tap2", "phy", "file", or
"qemu", being "qemu" the preferred one. Qemu only supports "qemu".
:param is_block_dev:
:returns: driver_name or None
"""
if CONF.libvirt.virt_type == "xen":
if is_block_dev:
return "phy"
else:
# 4002000 == 4.2.0
if hypervisor_version >= 4002000:
try:
execute('xend', 'status',
run_as_root=True, check_exit_code=True)
except OSError as exc:
if exc.errno == errno.ENOENT:
LOG.debug("xend is not found")
# libvirt will try to use libxl toolstack
return 'qemu'
else:
raise
except processutils.ProcessExecutionError:
LOG.debug("xend is not started")
# libvirt will try to use libxl toolstack
return 'qemu'
# libvirt will use xend/xm toolstack
try:
out, err = execute('tap-ctl', 'check', check_exit_code=False)
if out == 'ok\n':
# 4000000 == 4.0.0
if hypervisor_version > 4000000:
return "tap2"
else:
return "tap"
else:
LOG.info(_LI("tap-ctl check: %s"), out)
except OSError as exc:
if exc.errno == errno.ENOENT:
LOG.debug("tap-ctl tool is not installed")
else:
raise
return "file"
elif CONF.libvirt.virt_type in ('kvm', 'qemu'):
return "qemu"
else:
# UML doesn't want a driver_name set
return None
def get_disk_size(path, format=None):
"""Get the (virtual) size of a disk image
:param path: Path to the disk image
:param format: the on-disk format of path
:returns: Size (in bytes) of the given disk image as it would be seen
by a virtual machine.
"""
size = images.qemu_img_info(path, format).virtual_size
return int(size)
def get_disk_backing_file(path, basename=True, format=None):
"""Get the backing file of a disk image
:param path: Path to the disk image
:returns: a path to the image's backing store
"""
backing_file = images.qemu_img_info(path, format).backing_file
if backing_file and basename:
backing_file = os.path.basename(backing_file)
return backing_file
def copy_image(src, dest, host=None, receive=False,
on_execute=None, on_completion=None,
compression=True):
"""Copy a disk image to an existing directory
:param src: Source image
:param dest: Destination path
:param host: Remote host
:param receive: Reverse the rsync direction
:param on_execute: Callback method to store pid of process in cache
:param on_completion: Callback method to remove pid of process from cache
:param compression: Allows to use rsync operation with or without
compression
"""
if not host:
# We shell out to cp because that will intelligently copy
# sparse files. I.E. holes will not be written to DEST,
# rather recreated efficiently. In addition, since
# coreutils 8.11, holes can be read efficiently too.
# we add '-r' argument because ploop disks are directories
execute('cp', '-r', src, dest)
else:
if receive:
src = "%s:%s" % (utils.safe_ip_format(host), src)
else:
dest = "%s:%s" % (utils.safe_ip_format(host), dest)
remote_filesystem_driver = remotefs.RemoteFilesystem()
remote_filesystem_driver.copy_file(src, dest,
on_execute=on_execute, on_completion=on_completion,
compression=compression)
def write_to_file(path, contents, umask=None):
"""Write the given contents to a file
:param path: Destination file
:param contents: Desired contents of the file
:param umask: Umask to set when creating this file (will be reset)
"""
if umask:
saved_umask = os.umask(umask)
try:
with open(path, 'w') as f:
f.write(contents)
finally:
if umask:
os.umask(saved_umask)
def chown(path, owner):
"""Change ownership of file or directory
:param path: File or directory whose ownership to change
:param owner: Desired new owner (given as uid or username)
"""
execute('chown', owner, path, run_as_root=True)
def update_mtime(path):
"""Touch a file without being the owner.
:param path: File bump the mtime on
"""
execute('touch', '-c', path, run_as_root=True)
def _id_map_to_config(id_map):
return "%s:%s:%s" % (id_map.start, id_map.target, id_map.count)
def chown_for_id_maps(path, id_maps):
"""Change ownership of file or directory for an id mapped
environment
:param path: File or directory whose ownership to change
:param id_maps: List of type LibvirtConfigGuestIDMap
"""
uid_maps_str = ','.join([_id_map_to_config(id_map) for id_map in id_maps if
isinstance(id_map,
vconfig.LibvirtConfigGuestUIDMap)])
gid_maps_str = ','.join([_id_map_to_config(id_map) for id_map in id_maps if
isinstance(id_map,
vconfig.LibvirtConfigGuestGIDMap)])
execute('nova-idmapshift', '-i', '-u', uid_maps_str,
'-g', gid_maps_str, path, run_as_root=True)
def extract_snapshot(disk_path, source_fmt, out_path, dest_fmt):
"""Extract a snapshot from a disk image.
Note that nobody should write to the disk image during this operation.
:param disk_path: Path to disk image
:param out_path: Desired path of extracted snapshot
"""
# NOTE(markmc): ISO is just raw to qemu-img
if dest_fmt == 'iso':
dest_fmt = 'raw'
if dest_fmt == 'ploop':
dest_fmt = 'parallels'
qemu_img_cmd = ('qemu-img', 'convert', '-f', source_fmt, '-O', dest_fmt)
# Conditionally enable compression of snapshots.
if CONF.libvirt.snapshot_compression and dest_fmt == "qcow2":
qemu_img_cmd += ('-c',)
qemu_img_cmd += (disk_path, out_path)
execute(*qemu_img_cmd)
def load_file(path):
"""Read contents of file
:param path: File to read
"""
with open(path, 'r') as fp:
return fp.read()
def file_open(*args, **kwargs):
"""Open file
see built-in open() documentation for more details
Note: The reason this is kept in a separate module is to easily
be able to provide a stub module that doesn't alter system
state at all (for unit tests)
"""
return open(*args, **kwargs)
def file_delete(path):
"""Delete (unlink) file
Note: The reason this is kept in a separate module is to easily
be able to provide a stub module that doesn't alter system
state at all (for unit tests)
"""
return os.unlink(path)
def path_exists(path):
"""Returns if path exists
Note: The reason this is kept in a separate module is to easily
be able to provide a stub module that doesn't alter system
state at all (for unit tests)
"""
return os.path.exists(path)
def find_disk(virt_dom):
"""Find root device path for instance
May be file or device
"""
xml_desc = virt_dom.XMLDesc(0)
domain = etree.fromstring(xml_desc)
os_type = domain.find('os/type').text
driver = None
if CONF.libvirt.virt_type == 'lxc':
filesystem = domain.find('devices/filesystem')
driver = filesystem.find('driver')
source = filesystem.find('source')
disk_path = source.get('dir')
disk_path = disk_path[0:disk_path.rfind('rootfs')]
disk_path = os.path.join(disk_path, 'disk')
elif CONF.libvirt.virt_type == 'parallels' and os_type == vm_mode.EXE:
filesystem = domain.find('devices/filesystem')
driver = filesystem.find('driver')
source = filesystem.find('source')
disk_path = source.get('file')
else:
disk = domain.find('devices/disk')
driver = disk.find('driver')
source = disk.find('source')
disk_path = source.get('file') or source.get('dev')
if not disk_path and CONF.libvirt.images_type == 'rbd':
disk_path = source.get('name')
if disk_path:
disk_path = 'rbd:' + disk_path
if not disk_path:
raise RuntimeError(_("Can't retrieve root device path "
"from instance libvirt configuration"))
if driver is not None:
format = driver.get('type')
# This is a legacy quirk of libvirt/xen. Everything else should
# report the on-disk format in type.
if format == 'aio':
format = 'raw'
else:
format = None
return (disk_path, format)
def get_disk_type_from_path(path):
"""Retrieve disk type (raw, qcow2, lvm, ploop) for given file."""
if path.startswith('/dev'):
return 'lvm'
elif path.startswith('rbd:'):
return 'rbd'
elif (os.path.isdir(path) and
os.path.exists(os.path.join(path, "DiskDescriptor.xml"))):
return 'ploop'
# We can't reliably determine the type from this path
return None
def get_fs_info(path):
"""Get free/used/total space info for a filesystem
:param path: Any dirent on the filesystem
:returns: A dict containing:
:free: How much space is free (in bytes)
:used: How much space is used (in bytes)
:total: How big the filesystem is (in bytes)
"""
hddinfo = os.statvfs(path)
total = hddinfo.f_frsize * hddinfo.f_blocks
free = hddinfo.f_frsize * hddinfo.f_bavail
used = hddinfo.f_frsize * (hddinfo.f_blocks - hddinfo.f_bfree)
return {'total': total,
'free': free,
'used': used}
def fetch_image(context, target, image_id):
"""Grab image."""
images.fetch_to_raw(context, image_id, target)
def fetch_raw_image(context, target, image_id):
"""Grab initrd or kernel image.
This function does not attempt raw conversion, as these images will
already be in raw format.
"""
images.fetch(context, image_id, target)
def get_instance_path(instance, relative=False):
"""Determine the correct path for instance storage.
This method determines the directory name for instance storage.
:param instance: the instance we want a path for
:param relative: if True, just the relative path is returned
:returns: a path to store information about that instance
"""
if relative:
return instance.uuid
return os.path.join(CONF.instances_path, instance.uuid)
def get_instance_path_at_destination(instance, migrate_data=None):
"""Get the instance path on destination node while live migration.
This method determines the directory name for instance storage on
destination node, while live migration.
:param instance: the instance we want a path for
:param migrate_data: if not None, it is a dict which holds data
required for live migration without shared
storage.
:returns: a path to store information about that instance
"""
instance_relative_path = None
if migrate_data:
instance_relative_path = migrate_data.instance_relative_path
# NOTE(mikal): this doesn't use libvirt_utils.get_instance_path
# because we are ensuring that the same instance directory name
# is used as was at the source
if instance_relative_path:
instance_dir = os.path.join(CONF.instances_path,
instance_relative_path)
else:
instance_dir = get_instance_path(instance)
return instance_dir
def get_arch(image_meta):
"""Determine the architecture of the guest (or host).
This method determines the CPU architecture that must be supported by
the hypervisor. It gets the (guest) arch info from image_meta properties,
and it will fallback to the nova-compute (host) arch if no architecture
info is provided in image_meta.
:param image_meta: the metadata associated with the instance image
:returns: guest (or host) architecture
"""
if image_meta:
image_arch = image_meta.properties.get('hw_architecture')
if image_arch is not None:
return image_arch
return arch.from_host()
def is_mounted(mount_path, source=None):
"""Check if the given source is mounted at given destination point."""
try:
check_cmd = ['findmnt', '--target', mount_path]
if source:
check_cmd.extend(['--source', source])
utils.execute(*check_cmd)
return True
except processutils.ProcessExecutionError:
return False
except OSError as exc:
# info since it's not required to have this tool.
if exc.errno == errno.ENOENT:
LOG.info(_LI("findmnt tool is not installed"))
return False
def is_valid_hostname(hostname):
return re.match(r"^[\w\-\.:]+$", hostname)