Most of them are outdated, but provide historical design context.
They are not user documentation and should not be treated as such.
Documentation is available here.
Backup-Restore Disk-Snapshots
Summary
This feature is a complementary component for providing ability to backup and restore virtual machines. The feature introduces a support for downloading and uploading disk-snapshots, using the REST-API. Images transfer is facilitated using ovirt-imageio
The following backup/restore examples are facilitated using oVirt Python-SDK. oVirt REST-API/SDKs can be used in a similar manner.
Backup
Download a VM OVF
In order to fetch a VM configuration data, ‘all_content’ flag should be specified. Then, it can be written into a new file - that’s the OVF. Note: The OVF contains sufficient information about disks and snapshots to restore the VM to original state (e.g. alias/description/date). However, it isn’t automatically parsed by the system, but rather should be done by the SDK user.
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)
Download Disks
The following example demonstrates the procedure of downloading the non-active disk-snapshots of a specified disk. Hence, in order to include the active layer as well, either create a new snapshot for the disk in advance, or download the active disk-snapshot using theDownload Disk Example
In order to download the active
-
For each disk, iterate over its disk-snapshots and execute image transfer.
# 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) -
The ImageTransfer object should be specified with a ‘snapshot’ attribute.
transfer = transfers_service.add( types.ImageTransfer( snapshot=types.DiskSnapshot(id=disk_snapshot_id), direction=types.ImageTransferDirection.DOWNLOAD, ) )
Restore
Compose disk-snapshots chain
Using the saved images files, create a chain of the disk-snapshots. The chain is built by fetching the volume info (using qemu-img) of each file, and find the backing filename (volume’s parent). By maintaing a map between parent and child volumes, we can construct the chain, starting from base volume.
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
Create disks
For each disk, invoke disk creation for the base image using the generated images chain from previous step. The content of the disks will be uploaded in a later step.
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
)
]
)
)
Add a VM from OVF
Adding the saved VM is done by specifing the ovf data within the configuration element.
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
)
),
),
)
Create Snapshots
For each disk-snapshot in the chain, create a snapshot using the disk ID and image ID (and optionally the saved description).
# 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
)
)
]
),
)
Upload disks
For each disk-snapshot in the chain, start an upload transfer.
# 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()