openstack/nova
Code Issues Proposed changes

Make snapshots with qemu-img instead of libvirt

Browse Source 
* snapshot is only supposed to snapshot the root drive, whereas
   libvirt snapshots snapshot the memory and all attached disks
 * removes silly qemu_img flag
 * fixes bug 946830

Change-Id: I6afc9dbaa855f06864cd5a37f89ad63555e35d23
This commit is contained in:
Vishvananda Ishaya 2012-03-08 16:26:13 -08:00
parent f936594d9e
commit 7dbf9c7de2
5 changed files with 74 additions and 31 deletions
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4
nova/rootwrap/compute.py
View File

@ -179,6 +179,10 @@ filterlist = [
# nova/virt/xenapi/vm_utils.py: 'mkfs'
filters.CommandFilter("/sbin/mkfs", "root"),
# nova/virt/libvirt/utils.py: 'qemu-img'
filters.CommandFilter("/usr/bin/qemu-img", "root"),
# nova/virt/libvirt/connection.py:
filters.ReadFileFilter("/etc/iscsi/initiatorname.iscsi"),
]

8
nova/tests/fake_libvirt_utils.py
View File

@ -61,6 +61,14 @@ def chown(path, owner):
pass
def create_snapshot(disk_path, snapshot_name):
pass
def delete_snapshot(disk_path, snapshot_name):
pass
def extract_snapshot(disk_path, source_fmt, snapshot_name, out_path, dest_fmt):
files[out_path] = ''

10
nova/tests/test_libvirt.py
View File

@ -96,8 +96,14 @@ class FakeVirtDomain(object):
def name(self):
return "fake-domain %s" % self
def snapshotCreateXML(self, *args):
return FakeVirDomainSnapshot(self)
def info(self):
return [power_state.RUNNING, None, None, None, None]
def create(self):
pass
def managedSave(self, *args):
pass
def createWithFlags(self, launch_flags):
pass

25
nova/virt/libvirt/connection.py
View File

@ -616,21 +616,20 @@ class LibvirtConnection(driver.ComputeDriver):
if 'container_format' in base:
metadata['container_format'] = base['container_format']
# Make the snapshot
snapshot_name = uuid.uuid4().hex
snapshot_xml = """
<domainsnapshot>
<name>%s</name>
</domainsnapshot>
""" % snapshot_name
snapshot_ptr = virt_dom.snapshotCreateXML(snapshot_xml, 0)
# Find the disk
xml_desc = virt_dom.XMLDesc(0)
domain = ElementTree.fromstring(xml_desc)
source = domain.find('devices/disk/source')
disk_path = source.get('file')
snapshot_name = uuid.uuid4().hex
(state, _max_mem, _mem, _cpus, _t) = virt_dom.info()
if state == power_state.RUNNING:
virt_dom.managedSave(0)
# Make the snapshot
libvirt_utils.create_snapshot(disk_path, snapshot_name)
# Export the snapshot to a raw image
with utils.tempdir() as tmpdir:
try:
@ -638,6 +637,11 @@ class LibvirtConnection(driver.ComputeDriver):
libvirt_utils.extract_snapshot(disk_path, source_format,
snapshot_name, out_path,
image_format)
finally:
libvirt_utils.delete_snapshot(disk_path, snapshot_name)
if state == power_state.RUNNING:
virt_dom.create()
# Upload that image to the image service
with libvirt_utils.file_open(out_path) as image_file:
image_service.update(context,
@ -645,9 +649,6 @@ class LibvirtConnection(driver.ComputeDriver):
metadata,
image_file)
finally:
snapshot_ptr.delete(0)
@exception.wrap_exception()
def reboot(self, instance, network_info, reboot_type='SOFT'):
"""Reboot a virtual machine, given an instance reference."""

48
nova/virt/libvirt/utils.py
View File

@ -24,17 +24,11 @@ import random
from nova import exception
from nova import flags
from nova.openstack.common import cfg
from nova import utils
from nova.virt import images
qemu_img_opt = cfg.StrOpt('qemu_img',
default='qemu-img',
help='binary to use for qemu-img commands')
FLAGS = flags.FLAGS
FLAGS.register_opt(qemu_img_opt)
def execute(*args, **kwargs):
@ -63,7 +57,7 @@ def create_image(disk_format, path, size):
for megabytes, 'g' for gigabytes, 't' for terabytes). If no
prefix is given, it will be interpreted as bytes.
"""
execute(FLAGS.qemu_img, 'create', '-f', disk_format, path, size)
execute('qemu-img', 'create', '-f', disk_format, path, size)
def create_cow_image(backing_file, path):
@ -74,7 +68,7 @@ def create_cow_image(backing_file, path):
:param backing_file: Existing image on which to base the COW image
:param path: Desired location of the COW image
"""
execute(FLAGS.qemu_img, 'create', '-f', 'qcow2', '-o',
execute('qemu-img', 'create', '-f', 'qcow2', '-o',
'cluster_size=2M,backing_file=%s' % backing_file, path)
@ -85,7 +79,7 @@ def get_disk_size(path):
:returns: Size (in bytes) of the given disk image as it would be seen
by a virtual machine.
"""
out, err = execute(FLAGS.qemu_img, 'info', path)
out, err = execute('qemu-img', 'info', path)
size = [i.split('(')[1].split()[0] for i in out.split('\n')
if i.strip().find('virtual size') >= 0]
return int(size[0])
@ -97,7 +91,7 @@ def get_disk_backing_file(path):
:param path: Path to the disk image
:returns: a path to the image's backing store
"""
out, err = execute(FLAGS.qemu_img, 'info', path)
out, err = execute('qemu-img', 'info', path)
backing_file = [i.split('actual path:')[1].strip()[:-1]
for i in out.split('\n') if 0 <= i.find('backing file')]
if backing_file:
@ -168,7 +162,37 @@ def chown(path, owner):
:param path: File or directory whose ownership to change
:param owner: Desired new owner (given as uid or username)
"""
utils.execute('chown', owner, path, run_as_root=True)
execute('chown', owner, path, run_as_root=True)
def create_snapshot(disk_path, snapshot_name):
"""Create a snapshot in a disk image
:param disk_path: Path to disk image
:param snapshot_name: Name of snapshot in disk image
"""
qemu_img_cmd = ('qemu-img',
'snapshot',
'-c',
snapshot_name,
disk_path)
# NOTE(vish): libvirt changes ownership of images
execute(*qemu_img_cmd, run_as_root=True)
def delete_snapshot(disk_path, snapshot_name):
"""Create a snapshot in a disk image
:param disk_path: Path to disk image
:param snapshot_name: Name of snapshot in disk image
"""
qemu_img_cmd = ('qemu-img',
'snapshot',
'-d',
snapshot_name,
disk_path)
# NOTE(vish): libvirt changes ownership of images
execute(*qemu_img_cmd, run_as_root=True)
def extract_snapshot(disk_path, source_fmt, snapshot_name, out_path, dest_fmt):
@ -178,7 +202,7 @@ def extract_snapshot(disk_path, source_fmt, snapshot_name, out_path, dest_fmt):
:param snapshot_name: Name of snapshot in disk image
:param out_path: Desired path of extracted snapshot
"""
qemu_img_cmd = (FLAGS.qemu_img,
qemu_img_cmd = ('qemu-img',
'convert',
'-f',
source_fmt,