|
备份-还原磁盘快照
摘要
此功能是补充组件，用于提供备份和还原虚拟机的功能。该功能引入了对使用REST-API下载和上传磁盘快照的支持。使用ovirt-imageio促进图像传输
使用oVirt Python-SDK可简化以下备份/还原示例。oVirt REST-API / SDK可以类似的方式使用。
后备
下载VM OVF
完整的例子
为了获取VM配置数据，应指定'all_content'标志。然后，可以将其写入一个新文件-OVF。注意：OVF包含有关磁盘和快照的足够信息，可以将VM恢复到原始状态（例如，别名/描述/日期）。但是，它不是由系统自动解析的，而是应该由SDK用户完成的。
vm_name = 'myvm'
vm = vms_service.list(search="name=%s" % vm_name, all_content=True)[0]
ovf_filename = "%s.ovf" % vm.id
with open(ovf_filename, "wb") as ovf_file:
ovf_file.write(vm.initialization.configuration.data)
下载磁盘
完整的例子
以下示例演示了下载指定磁盘的非活动磁盘快照的过程。因此，为了也包括活动层，请预先为磁盘创建一个新的快照，或者使用“ 下载磁盘”示例下载活动磁盘快照
为了下载活跃
对于每个磁盘，遍历其磁盘快照并执行映像传输。
# Set relevant disk and stroage domain IDs
disk_id = 'ccdd6487-0a8f-40c8-9f45-40e0e2b30d79'
sd_name = 'mydata'
# Get a reference to the storage domains service:
storage_domains_service = system_service.storage_domains_service()
# Look up for the storage domain by name:
storage_domain = storage_domains_service.list(search='name=%s' % sd_name)[0]
# Get a reference to the storage domain service in which the disk snapshots reside:
storage_domain_service = storage_domains_service.storage_domain_service(storage_domain.id)
# Get a reference to the disk snapshots service:
disk_snapshot_service = storage_domain_service.disk_snapshots_service()
# Get a list of disk snapshots by a disk ID
all_disk_snapshots = disk_snapshot_service.list()
# Filter disk snapshots list by disk id
disk_snapshots = [s for s in all_disk_snapshots if s.disk.id == disk_id]
# Download disk snapshots
for disk_snapshot in disk_snapshots:
download_disk_snapshot(disk_snapshot)
应使用“快照”属性指定ImageTransfer对象。
transfer = transfers_service.add(
types.ImageTransfer(
snapshot=types.DiskSnapshot(id=disk_snapshot_id),
direction=types.ImageTransferDirection.DOWNLOAD,
)
)
恢复
完整的例子
组成磁盘快照链
使用保存的图像文件，创建一个磁盘快照链。通过获取每个文件的卷信息（使用qemu-img）并找到后备文件名（卷的父文件）来构建链。通过维护父卷和子卷之间的映射，我们可以从基本卷开始构建链。
volumes_info = {} # {filename -> vol_info}
backing_files = {} # {backing_file (parent) -> vol_info (child)}
for root, dirs, file_names in os.walk(disk_path):
for file_name in file_names:
volume_info = get_volume_info("%s/%s" % (disk_path, file_name))
volumes_info[file_name] = volume_info
if 'full-backing-filename' in volume_info:
backing_files[volume_info['full-backing-filename']] = volume_info
base_volume = [v for v in volumes_info.values() if 'full-backing-filename' not in v ][0]
child = backing_files[base_volume['filename']]
images_chain = [base_volume]
while child != None:
images_chain.append(child)
parent = child
if parent['filename'] in backing_files:
child = backing_files[parent['filename']]
else:
child = None
return images_chain
创建磁盘
对于每个磁盘，使用上一步中生成的映像链调用基本映像的磁盘创建。磁盘的内容将在以后的步骤中上载。
base_image = images_chain[0]
initial_size = base_image['actual-size']
provisioned_size = base_image['virtual-size']
image_id = os.path.basename(base_image['filename'])
disk = disks_service.add(
types.Disk(
id=disk_id,
image_id=image_id,
name=disk_id,
format=types.DiskFormat.RAW,
provisioned_size=provisioned_size,
initial_size=initial_size,
storage_domains=[
types.StorageDomain(
name=sd_name
)
]
)
)
从OVF添加VM
通过在配置元素中指定ovf数据来添加保存的VM。
ovf_file_path = 'c3a8e806-106d-4aff-b59a-3a113eabf5a9.ovf'
ovf_data = open(ovf_file_path, 'r').read()
vms_service = system_service.vms_service()
vm = vms_service.add(
types.Vm(
cluster=types.Cluster(
name='Default',
),
initialization = types.Initialization(
configuration = types.Configuration(
type = types.ConfigurationType.OVF,
data = ovf_data
)
),
),
)
创建快照
对于链中的每个磁盘快照，使用磁盘ID和映像ID（以及可选的已保存描述）创建快照。
# Locate the service that manages the snapshots of the virtual machine:
snapshots_service = vm_service.snapshots_service()
# Add the new snapshot:
snapshot = snapshots_service.add(
types.Snapshot(
description=description,
disk_attachments=[
types.DiskAttachment(
disk=types.Disk(
id=disk_id,
image_id=image_id
)
)
]
),
)
上传磁盘
对于链中的每个磁盘快照，开始上载传输。
# Get a reference to the service that manages the image transfer:
transfers_service = system_service.image_transfers_service()
# Add a new image transfer:
transfer = transfers_service.add(
types.ImageTransfer(
snapshot=types.DiskSnapshot(id=disk_snapshot_id),
direction=types.ImageTransferDirection.UPLOAD,
)
)
# Get reference to the created transfer service:
transfer_service = transfers_service.image_transfer_service(transfer.id)
while transfer.phase == types.ImageTransferPhase.INITIALIZING:
time.sleep(1)
transfer = transfer_service.get()
try:
proxy_url = urlparse(transfer.proxy_url)
proxy_connection = get_proxy_connection(proxy_url)
path = disk_path
# Set needed headers for uploading:
upload_headers = {
'Authorization': transfer.signed_ticket,
}
with open(path, "rb") as disk:
size = os.path.getsize(path)
chunk_size = 1024 * 1024 * 8
pos = 0
while pos < size:
# Extend the transfer session.
transfer_service.extend()
# Set the content range, according to the chunk being sent.
upload_headers['Content-Range'] = "bytes %d-%d/%d" % (pos, min(pos + chunk_size, size) - 1, size)
# Perform the request.
proxy_connection.request(
'PUT',
proxy_url.path,
disk.read(chunk_size),
headers=upload_headers,
)
# Print response
r = proxy_connection.getresponse()
print r.status, r.reason, "Completed", "{:.0%}".format(pos / float(size))
# Continue to next chunk.
pos += chunk_size
print "Completed", "{:.0%}".format(pos / float(size))
finally:
# Finalize the session.
transfer_service.finalize()
附录
Python SDK范例
下载VM OVF
下载磁盘快照
上传磁盘快照
下载磁盘
上传磁盘
(责任编辑：IT) |