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The nova.virt.xenapi.vm_utils Module

Helper methods for operations related to the management of VM records and their attributes like VDIs, VIFs, as well as their lookup functions.

class ImageType

Enumeration class for distinguishing different image types

0 - kernel image (goes on dom0’s filesystem)
1 - ramdisk image (goes on dom0’s filesystem)
2 - disk image (local SR, partitioned by objectstore plugin)
3 - raw disk image (local SR, NOT partitioned by plugin)
4 - vhd disk image (local SR, NOT inspected by XS, PV assumed for
linux, HVM assumed for Windows)
5 - ISO disk image (local SR, NOT partitioned by plugin)
DISK = 2
DISK_ISO = 5
DISK_ISO_STR = 'iso'
DISK_RAW = 3
DISK_RAW_STR = 'os_raw'
DISK_STR = 'os'
DISK_VHD = 4
DISK_VHD_STR = 'vhd'
KERNEL = 0
KERNEL_STR = 'kernel'
RAMDISK = 1
RAMDISK_STR = 'ramdisk'
classmethod from_string(image_type_str)
classmethod to_string(image_type)
class VMHelper

Bases: nova.virt.xenapi.HelperBase

The class that wraps the helper methods together.

classmethod auto_configure_disk(session, vdi_ref, new_gb)

Partition and resize FS to match the size specified by instance_types.root_gb.

This is a fail-safe to prevent accidentally destroying data on a disk erroneously marked as auto_disk_config=True.

The criteria for allowing resize are:

  1. ‘auto_disk_config’ must be true for the instance (and image). (If we’ve made it here, then auto_disk_config=True.)
  2. The disk must have only one partition.
  3. The file-system on the one partition must be ext3 or ext4.
classmethod clone_vdi(session, vdi_to_clone_ref)

Clones a VDI and return the new VDIs reference.

classmethod compile_diagnostics(record)

Compile VM diagnostics data

classmethod compile_info(record)

Fill record with VM status information

classmethod compile_metrics(start_time, stop_time=None)

Compile bandwidth usage, cpu, and disk metrics for all VMs on this host

classmethod copy_vdi(session, sr_ref, vdi_to_copy_ref)

Copy a VDI and return the new VDIs reference.

classmethod create_image(context, session, instance, image, user_id, project_id, image_type)

Creates VDI from the image stored in the local cache. If the image is not present in the cache, it streams it from glance.

Returns: A list of dictionaries that describe VDIs

classmethod create_kernel_image(context, session, instance, image, user_id, project_id, image_type)

Creates kernel/ramdisk file from the image stored in the cache. If the image is not present in the cache, it streams it from glance.

Returns: A list of dictionaries that describe VDIs

classmethod create_snapshot(session, instance, vm_ref, label)

Creates Snapshot (Template) VM, Snapshot VBD, Snapshot VDI, Snapshot VHD

classmethod create_vbd(session, vm_ref, vdi_ref, userdevice, vbd_type='disk', read_only=False, bootable=False)

Create a VBD record and returns its reference.

classmethod create_vdi(session, sr_ref, name_label, virtual_size, read_only)

Create a VDI record and returns its reference.

classmethod create_vm(session, instance, kernel, ramdisk, use_pv_kernel=False)

Create a VM record. Returns a Deferred that gives the new VM reference. the use_pv_kernel flag indicates whether the guest is HVM or PV

There are 3 scenarios:

  1. Using paravirtualization, kernel passed in
  2. Using paravirtualization, kernel within the image
  3. Using hardware virtualization
classmethod destroy_vbd(session, vbd_ref)

Destroy VBD from host database

classmethod destroy_vdi(session, vdi_ref)
classmethod determine_disk_image_type(image_meta)

Disk Image Types are used to determine where the kernel will reside within an image. To figure out which type we’re dealing with, we use the following rules:

  1. If we’re using Glance, we can use the image_type field to determine the image_type
  2. If we’re not using Glance, then we need to deduce this based on whether a kernel_id is specified.
classmethod determine_is_pv(session, vdi_ref, disk_image_type, os_type)

Determine whether the VM will use a paravirtualized kernel or if it will use hardware virtualization.

  1. Glance (VHD): then we use os_type, raise if not set
  2. Glance (DISK_RAW): use Pygrub to figure out if pv kernel is available
  3. Glance (DISK): pv is assumed
  4. Glance (DISK_ISO): no pv is assumed
classmethod ensure_free_mem(session, instance)
classmethod fetch_blank_disk(session, instance_type_id)
classmethod fetch_image(context, session, instance, image, _user_id, _project_id, image_type)

Fetch image from glance based on image type.

Returns: A single filename if image_type is KERNEL or RAMDISK
A list of dictionaries that describe VDIs, otherwise
classmethod find_cached_image(session, image_id, sr_ref)

Returns the vdi-ref of the cached image.

classmethod find_iso_sr(session)

Return the storage repository to hold ISO images

classmethod find_sr(session)

Return the storage repository to hold VM images

classmethod find_vbd_by_number(session, vm_ref, number)

Get the VBD reference from the device number

classmethod generate_ephemeral(session, instance, vm_ref, userdevice, size_gb)
classmethod generate_swap(session, instance, vm_ref, userdevice, swap_mb)
classmethod get_sr_path(session)

Return the path to our storage repository

This is used when we’re dealing with VHDs directly, either by taking snapshots or by restoring an image in the DISK_VHD format.

classmethod get_vdi_for_vm_safely(session, vm_ref)

Retrieves the primary VDI for a VM

classmethod is_snapshot(session, vm)
classmethod list_vms(session)
classmethod lookup(session, name_label)

Look the instance up and return it if available

classmethod lookup_kernel_ramdisk(session, vm)
classmethod lookup_vm_vdis(session, vm_ref)

Look for the VDIs that are attached to the VM

classmethod preconfigure_instance(session, instance, vdi_ref, network_info)

Makes alterations to the image before launching as part of spawn.

classmethod resize_disk(session, vdi_ref, instance_type)
classmethod safe_find_iso_sr(session)

Same as find_iso_sr except raises a NotFound exception if SR cannot be determined

classmethod safe_find_sr(session)

Same as find_sr except raises a NotFound exception if SR cannot be determined

classmethod scan_default_sr(session)

Looks for the system default SR and triggers a re-scan

classmethod scan_sr(session, sr_ref=None)

Scans the SR specified by sr_ref

classmethod set_vdi_name_label(session, vdi_uuid, name_label)
classmethod set_vm_name_label(session, vm_ref, name_label)
classmethod unplug_vbd(session, vbd_ref)

Unplug VBD from VM

classmethod upload_image(context, session, instance, vdi_uuids, image_id)

Requests that the Glance plugin bundle the specified VDIs and push them into Glance using the specified human-friendly name.

average_series(data, col, until=None)
get_rrd(server, vm_uuid)

Return the VM RRD XML as a string

get_rrd_server()

Return server’s scheme and address to use for retrieving RRD XMLs.

get_rrd_updates(server, start_time)

Return the RRD updates XML as a string

get_this_vm_ref(session)
get_this_vm_uuid()
get_vhd_parent(session, vdi_rec)

Returns the VHD parent of the given VDI record, as a (ref, rec) pair. Returns None if we’re at the root of the tree.

get_vhd_parent_uuid(session, vdi_ref)
integrate_series(data, col, start, until=None)
parse_rrd_data(doc)
parse_rrd_meta(doc)
parse_rrd_update(doc, start, until=None)
remap_vbd_dev(dev)

Return the appropriate location for a plugged-in VBD device

Ubuntu Maverick moved xvd? -> sd?. This is considered a bug and will be fixed in future versions:

For now, we work around it by just doing a string replace.

vdi_attached_here(*args, **kwds)
walk_vdi_chain(session, vdi_uuid)

Yield vdi_recs for each element in a VDI chain