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OpenStack Study: driver.py**** CubicPower OpenStack Study ****
# Copyright (c) 2010 Citrix Systems, Inc. # Copyright 2010 OpenStack Foundation # # 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. """ A driver for XenServer or Xen Cloud Platform. **Related Flags** :connection_url: URL for connection to XenServer/Xen Cloud Platform. :connection_username: Username for connection to XenServer/Xen Cloud Platform (default: root). :connection_password: Password for connection to XenServer/Xen Cloud Platform. :target_host: the iSCSI Target Host IP address, i.e. the IP address for the nova-volume host :target_port: iSCSI Target Port, 3260 Default :iqn_prefix: IQN Prefix, e.g. 'iqn.2010-10.org.openstack' **Variable Naming Scheme** - suffix "_ref" for opaque references - suffix "_uuid" for UUIDs - suffix "_rec" for record objects """ import math from oslo.config import cfg import six.moves.urllib.parse as urlparse from nova.openstack.common.gettextutils import _ from nova.openstack.common import jsonutils from nova.openstack.common import log as logging from nova.openstack.common import units from nova import utils from nova.virt import driver from nova.virt.xenapi.client import session from nova.virt.xenapi import host from nova.virt.xenapi import pool from nova.virt.xenapi import vm_utils from nova.virt.xenapi import vmops from nova.virt.xenapi import volumeops LOG = logging.getLogger(__name__) xenapi_opts = [ cfg.StrOpt('connection_url', deprecated_name='xenapi_connection_url', deprecated_group='DEFAULT', help='URL for connection to XenServer/Xen Cloud Platform. ' 'A special value of unix://local can be used to connect ' 'to the local unix socket. ' 'Required if compute_driver=xenapi.XenAPIDriver'), cfg.StrOpt('connection_username', default='root', deprecated_name='xenapi_connection_username', deprecated_group='DEFAULT', help='Username for connection to XenServer/Xen Cloud Platform. ' 'Used only if compute_driver=xenapi.XenAPIDriver'), cfg.StrOpt('connection_password', deprecated_name='xenapi_connection_password', deprecated_group='DEFAULT', help='Password for connection to XenServer/Xen Cloud Platform. ' 'Used only if compute_driver=xenapi.XenAPIDriver', secret=True), cfg.FloatOpt('vhd_coalesce_poll_interval', default=5.0, deprecated_name='xenapi_vhd_coalesce_poll_interval', deprecated_group='DEFAULT', help='The interval used for polling of coalescing vhds. ' 'Used only if compute_driver=xenapi.XenAPIDriver'), cfg.BoolOpt('check_host', default=True, deprecated_name='xenapi_check_host', deprecated_group='DEFAULT', help='Ensure compute service is running on host XenAPI ' 'connects to.'), cfg.IntOpt('vhd_coalesce_max_attempts', default=20, deprecated_name='xenapi_vhd_coalesce_max_attempts', deprecated_group='DEFAULT', help='Max number of times to poll for VHD to coalesce. ' 'Used only if compute_driver=xenapi.XenAPIDriver'), cfg.StrOpt('sr_base_path', default='/var/run/sr-mount', deprecated_name='xenapi_sr_base_path', deprecated_group='DEFAULT', help='Base path to the storage repository'), cfg.StrOpt('target_host', deprecated_name='target_host', deprecated_group='DEFAULT', help='The iSCSI Target Host'), cfg.StrOpt('target_port', default='3260', deprecated_name='target_port', deprecated_group='DEFAULT', help='The iSCSI Target Port, default is port 3260'), cfg.StrOpt('iqn_prefix', default='iqn.2010-10.org.openstack', deprecated_name='iqn_prefix', deprecated_group='DEFAULT', help='IQN Prefix'), # NOTE(sirp): This is a work-around for a bug in Ubuntu Maverick, # when we pull support for it, we should remove this cfg.BoolOpt('remap_vbd_dev', default=False, deprecated_name='xenapi_remap_vbd_dev', deprecated_group='DEFAULT', help='Used to enable the remapping of VBD dev ' '(Works around an issue in Ubuntu Maverick)'), cfg.StrOpt('remap_vbd_dev_prefix', default='sd', deprecated_name='xenapi_remap_vbd_dev_prefix', deprecated_group='DEFAULT', help='Specify prefix to remap VBD dev to ' '(ex. /dev/xvdb -> /dev/sdb)'), ] CONF = cfg.CONF # xenapi options in the DEFAULT group were deprecated in Icehouse CONF.register_opts(xenapi_opts, 'xenserver') CONF.import_opt('host', 'nova.netconf') OVERHEAD_BASE = 3 OVERHEAD_PER_MB = 0.00781 OVERHEAD_PER_VCPU = 1.5
**** CubicPower OpenStack Study **** class XenAPIDriver(driver.ComputeDriver): """A connection to XenServer or Xen Cloud Platform."""
**** CubicPower OpenStack Study **** def __init__(self, virtapi, read_only=False): super(XenAPIDriver, self).__init__(virtapi) url = CONF.xenserver.connection_url username = CONF.xenserver.connection_username password = CONF.xenserver.connection_password if not url or password is None: raise Exception(_('Must specify connection_url, ' 'connection_username (optionally), and ' 'connection_password to use ' 'compute_driver=xenapi.XenAPIDriver')) self._session = session.XenAPISession(url, username, password) self._volumeops = volumeops.VolumeOps(self._session) self._host_state = None self._host = host.Host(self._session, self.virtapi) self._vmops = vmops.VMOps(self._session, self.virtapi) self._initiator = None self._hypervisor_hostname = None self._pool = pool.ResourcePool(self._session, self.virtapi) @property
**** CubicPower OpenStack Study **** def host_state(self): if not self._host_state: self._host_state = host.HostState(self._session) return self._host_state
**** CubicPower OpenStack Study **** def init_host(self, host): if CONF.xenserver.check_host: vm_utils.ensure_correct_host(self._session) try: vm_utils.cleanup_attached_vdis(self._session) except Exception: LOG.exception(_('Failure while cleaning up attached VDIs'))
**** CubicPower OpenStack Study **** def instance_exists(self, instance_name): """Checks existence of an instance on the host. :param instance_name: The name of the instance to lookup Returns True if an instance with the supplied name exists on the host, False otherwise. NOTE(belliott): This is an override of the base method for efficiency. """ return self._vmops.instance_exists(instance_name)
**** CubicPower OpenStack Study **** def estimate_instance_overhead(self, instance_info): """Get virtualization overhead required to build an instance of the given flavor. :param instance_info: Instance/flavor to calculate overhead for. :returns: Overhead memory in MB. """ # XenServer memory overhead is proportional to the size of the # VM. Larger flavor VMs become more efficient with respect to # overhead. # interpolated formula to predict overhead required per vm. # based on data from: # https://wiki.openstack.org/wiki/XenServer/Overhead # Some padding is done to each value to fit all available VM data memory_mb = instance_info['memory_mb'] vcpus = instance_info.get('vcpus', 1) overhead = ((memory_mb * OVERHEAD_PER_MB) + (vcpus * OVERHEAD_PER_VCPU) + OVERHEAD_BASE) overhead = math.ceil(overhead) return {'memory_mb': overhead}
**** CubicPower OpenStack Study **** def list_instances(self): """List VM instances.""" return self._vmops.list_instances()
**** CubicPower OpenStack Study **** def list_instance_uuids(self): """Get the list of nova instance uuids for VMs found on the hypervisor. """ return self._vmops.list_instance_uuids()
**** CubicPower OpenStack Study **** def spawn(self, context, instance, image_meta, injected_files, admin_password, network_info=None, block_device_info=None): """Create VM instance.""" self._vmops.spawn(context, instance, image_meta, injected_files, admin_password, network_info, block_device_info)
**** CubicPower OpenStack Study **** def confirm_migration(self, migration, instance, network_info): """Confirms a resize, destroying the source VM.""" # TODO(Vek): Need to pass context in for access to auth_token self._vmops.confirm_migration(migration, instance, network_info)
**** CubicPower OpenStack Study **** def finish_revert_migration(self, context, instance, network_info, block_device_info=None, power_on=True): """Finish reverting a resize.""" # NOTE(vish): Xen currently does not use network info. self._vmops.finish_revert_migration(context, instance, block_device_info, power_on)
**** CubicPower OpenStack Study **** def finish_migration(self, context, migration, instance, disk_info, network_info, image_meta, resize_instance=False, block_device_info=None, power_on=True): """Completes a resize, turning on the migrated instance.""" self._vmops.finish_migration(context, migration, instance, disk_info, network_info, image_meta, resize_instance, block_device_info, power_on)
**** CubicPower OpenStack Study **** def snapshot(self, context, instance, image_id, update_task_state): """Create snapshot from a running VM instance.""" self._vmops.snapshot(context, instance, image_id, update_task_state)
**** CubicPower OpenStack Study **** def reboot(self, context, instance, network_info, reboot_type, block_device_info=None, bad_volumes_callback=None): """Reboot VM instance.""" self._vmops.reboot(instance, reboot_type, bad_volumes_callback=bad_volumes_callback)
**** CubicPower OpenStack Study **** def set_admin_password(self, instance, new_pass): """Set the root/admin password on the VM instance.""" self._vmops.set_admin_password(instance, new_pass)
**** CubicPower OpenStack Study **** def inject_file(self, instance, b64_path, b64_contents): """Create a file on the VM instance. The file path and contents should be base64-encoded. """ self._vmops.inject_file(instance, b64_path, b64_contents)
**** CubicPower OpenStack Study **** def change_instance_metadata(self, context, instance, diff): """Apply a diff to the instance metadata.""" self._vmops.change_instance_metadata(instance, diff)
**** CubicPower OpenStack Study **** def destroy(self, context, instance, network_info, block_device_info=None, destroy_disks=True): """Destroy VM instance.""" self._vmops.destroy(instance, network_info, block_device_info, destroy_disks)
**** CubicPower OpenStack Study **** def cleanup(self, context, instance, network_info, block_device_info=None, destroy_disks=True): """Cleanup after instance being destroyed by Hypervisor.""" pass
**** CubicPower OpenStack Study **** def pause(self, instance): """Pause VM instance.""" self._vmops.pause(instance)
**** CubicPower OpenStack Study **** def unpause(self, instance): """Unpause paused VM instance.""" self._vmops.unpause(instance)
**** CubicPower OpenStack Study **** def migrate_disk_and_power_off(self, context, instance, dest, flavor, network_info, block_device_info=None): """Transfers the VHD of a running instance to another host, then shuts off the instance copies over the COW disk """ # NOTE(vish): Xen currently does not use network info. return self._vmops.migrate_disk_and_power_off(context, instance, dest, flavor, block_device_info)
**** CubicPower OpenStack Study **** def suspend(self, instance): """suspend the specified instance.""" self._vmops.suspend(instance)
**** CubicPower OpenStack Study **** def resume(self, context, instance, network_info, block_device_info=None): """resume the specified instance.""" self._vmops.resume(instance)
**** CubicPower OpenStack Study **** def rescue(self, context, instance, network_info, image_meta, rescue_password): """Rescue the specified instance.""" self._vmops.rescue(context, instance, network_info, image_meta, rescue_password)
**** CubicPower OpenStack Study **** def set_bootable(self, instance, is_bootable): """Set the ability to power on/off an instance.""" self._vmops.set_bootable(instance, is_bootable)
**** CubicPower OpenStack Study **** def unrescue(self, instance, network_info): """Unrescue the specified instance.""" self._vmops.unrescue(instance)
**** CubicPower OpenStack Study **** def power_off(self, instance): """Power off the specified instance.""" self._vmops.power_off(instance)
**** CubicPower OpenStack Study **** def power_on(self, context, instance, network_info, block_device_info=None): """Power on the specified instance.""" self._vmops.power_on(instance)
**** CubicPower OpenStack Study **** def soft_delete(self, instance): """Soft delete the specified instance.""" self._vmops.soft_delete(instance)
**** CubicPower OpenStack Study **** def restore(self, instance): """Restore the specified instance.""" self._vmops.restore(instance)
**** CubicPower OpenStack Study **** def poll_rebooting_instances(self, timeout, instances): """Poll for rebooting instances.""" self._vmops.poll_rebooting_instances(timeout, instances)
**** CubicPower OpenStack Study **** def reset_network(self, instance): """reset networking for specified instance.""" self._vmops.reset_network(instance)
**** CubicPower OpenStack Study **** def inject_network_info(self, instance, network_info): """inject network info for specified instance.""" self._vmops.inject_network_info(instance, network_info)
**** CubicPower OpenStack Study **** def plug_vifs(self, instance_ref, network_info): """Plug VIFs into networks.""" self._vmops.plug_vifs(instance_ref, network_info)
**** CubicPower OpenStack Study **** def unplug_vifs(self, instance_ref, network_info): """Unplug VIFs from networks.""" self._vmops.unplug_vifs(instance_ref, network_info)
**** CubicPower OpenStack Study **** def get_info(self, instance): """Return data about VM instance.""" return self._vmops.get_info(instance)
**** CubicPower OpenStack Study **** def get_diagnostics(self, instance): """Return data about VM diagnostics.""" return self._vmops.get_diagnostics(instance)
**** CubicPower OpenStack Study **** def get_all_bw_counters(self, instances): """Return bandwidth usage counters for each interface on each running VM. """ # we only care about VMs that correspond to a nova-managed # instance: imap = dict([(inst['name'], inst['uuid']) for inst in instances]) bwcounters = [] # get a dictionary of instance names. values are dictionaries # of mac addresses with values that are the bw counters: # e.g. {'instance-001' : { 12:34:56:78:90:12 : {'bw_in': 0, ....}} all_counters = self._vmops.get_all_bw_counters() for instance_name, counters in all_counters.iteritems(): if instance_name in imap: # yes these are stats for a nova-managed vm # correlate the stats with the nova instance uuid: for vif_counter in counters.values(): vif_counter['uuid'] = imap[instance_name] bwcounters.append(vif_counter) return bwcounters
**** CubicPower OpenStack Study **** def get_console_output(self, context, instance): """Return snapshot of console.""" return self._vmops.get_console_output(instance)
**** CubicPower OpenStack Study **** def get_vnc_console(self, context, instance): """Return link to instance's VNC console.""" return self._vmops.get_vnc_console(instance)
**** CubicPower OpenStack Study **** def get_volume_connector(self, instance): """Return volume connector information.""" if not self._initiator or not self._hypervisor_hostname: stats = self.get_host_stats(refresh=True) try: self._initiator = stats['host_other-config']['iscsi_iqn'] self._hypervisor_hostname = stats['host_hostname'] except (TypeError, KeyError) as err: LOG.warn(_('Could not determine key: %s') % err, instance=instance) self._initiator = None return { 'ip': self.get_host_ip_addr(), 'initiator': self._initiator, 'host': self._hypervisor_hostname } @staticmethod
**** CubicPower OpenStack Study **** def get_host_ip_addr(): xs_url = urlparse.urlparse(CONF.xenserver.connection_url) return xs_url.netloc
**** CubicPower OpenStack Study **** def attach_volume(self, context, connection_info, instance, mountpoint, disk_bus=None, device_type=None, encryption=None): """Attach volume storage to VM instance.""" return self._volumeops.attach_volume(connection_info, instance['name'], mountpoint)
**** CubicPower OpenStack Study **** def detach_volume(self, connection_info, instance, mountpoint, encryption=None): """Detach volume storage from VM instance.""" return self._volumeops.detach_volume(connection_info, instance['name'], mountpoint)
**** CubicPower OpenStack Study **** def get_console_pool_info(self, console_type): xs_url = urlparse.urlparse(CONF.xenserver.connection_url) return {'address': xs_url.netloc, 'username': CONF.xenserver.connection_username, 'password': CONF.xenserver.connection_password}
**** CubicPower OpenStack Study **** def get_available_resource(self, nodename): """Retrieve resource information. This method is called when nova-compute launches, and as part of a periodic task that records the results in the DB. :param nodename: ignored in this driver :returns: dictionary describing resources """ host_stats = self.get_host_stats(refresh=True) # Updating host information total_ram_mb = host_stats['host_memory_total'] / units.Mi # NOTE(belliott) memory-free-computed is a value provided by XenServer # for gauging free memory more conservatively than memory-free. free_ram_mb = host_stats['host_memory_free_computed'] / units.Mi total_disk_gb = host_stats['disk_total'] / units.Gi used_disk_gb = host_stats['disk_used'] / units.Gi hyper_ver = utils.convert_version_to_int(self._session.product_version) dic = {'vcpus': host_stats['host_cpu_info']['cpu_count'], 'memory_mb': total_ram_mb, 'local_gb': total_disk_gb, 'vcpus_used': host_stats['vcpus_used'], 'memory_mb_used': total_ram_mb - free_ram_mb, 'local_gb_used': used_disk_gb, 'hypervisor_type': 'xen', 'hypervisor_version': hyper_ver, 'hypervisor_hostname': host_stats['host_hostname'], # Todo(bobba) cpu_info may be in a format not supported by # arch_filter.py - see libvirt/driver.py get_cpu_info 'cpu_info': jsonutils.dumps(host_stats['host_cpu_info']), 'supported_instances': jsonutils.dumps( host_stats['supported_instances']), 'pci_passthrough_devices': jsonutils.dumps( host_stats['pci_passthrough_devices'])} return dic
**** CubicPower OpenStack Study **** def ensure_filtering_rules_for_instance(self, instance_ref, network_info): # NOTE(salvatore-orlando): it enforces security groups on # host initialization and live migration. # In XenAPI we do not assume instances running upon host initialization return
**** CubicPower OpenStack Study **** def check_can_live_migrate_destination(self, ctxt, instance_ref, src_compute_info, dst_compute_info, block_migration=False, disk_over_commit=False): """Check if it is possible to execute live migration. :param context: security context :param instance_ref: nova.db.sqlalchemy.models.Instance object :param block_migration: if true, prepare for block migration :param disk_over_commit: if true, allow disk over commit """ return self._vmops.check_can_live_migrate_destination(ctxt, instance_ref, block_migration, disk_over_commit)
**** CubicPower OpenStack Study **** def check_can_live_migrate_destination_cleanup(self, ctxt, dest_check_data): """Do required cleanup on dest host after check_can_live_migrate calls :param ctxt: security context :param disk_over_commit: if true, allow disk over commit """ pass
**** CubicPower OpenStack Study **** def check_can_live_migrate_source(self, ctxt, instance_ref, dest_check_data): """Check if it is possible to execute live migration. This checks if the live migration can succeed, based on the results from check_can_live_migrate_destination. :param context: security context :param instance_ref: nova.db.sqlalchemy.models.Instance :param dest_check_data: result of check_can_live_migrate_destination includes the block_migration flag """ return self._vmops.check_can_live_migrate_source(ctxt, instance_ref, dest_check_data)
**** CubicPower OpenStack Study **** def get_instance_disk_info(self, instance_name): """Used by libvirt for live migration. We rely on xenapi checks to do this for us. """ pass
**** CubicPower OpenStack Study **** def live_migration(self, ctxt, instance_ref, dest, post_method, recover_method, block_migration=False, migrate_data=None): """Performs the live migration of the specified instance. :param ctxt: security context :param instance_ref: nova.db.sqlalchemy.models.Instance object instance object that is migrated. :param dest: destination host :param post_method: post operation method. expected nova.compute.manager.post_live_migration. :param recover_method: recovery method when any exception occurs. expected nova.compute.manager.recover_live_migration. :param block_migration: if true, migrate VM disk. :param migrate_data: implementation specific params """ self._vmops.live_migrate(ctxt, instance_ref, dest, post_method, recover_method, block_migration, migrate_data)
**** CubicPower OpenStack Study **** def rollback_live_migration_at_destination(self, context, instance, network_info, block_device_info): # NOTE(johngarbutt) Destroying the VM is not appropriate here # and in the cases where it might make sense, # XenServer has already done it. # TODO(johngarbutt) investigate if any cleanup is required here pass
**** CubicPower OpenStack Study **** def pre_live_migration(self, context, instance_ref, block_device_info, network_info, data, migrate_data=None): """Preparation live migration. :param block_device_info: It must be the result of _get_instance_volume_bdms() at compute manager. """ # TODO(JohnGarbutt) look again when boot-from-volume hits trunk pre_live_migration_result = {} pre_live_migration_result['sr_uuid_map'] = \ self._vmops.attach_block_device_volumes(block_device_info) return pre_live_migration_result
**** CubicPower OpenStack Study **** def post_live_migration(self, ctxt, instance_ref, block_device_info, migrate_data=None): """Post operation of live migration at source host. :param ctxt: security context :instance_ref: instance object that was migrated :block_device_info: instance block device information :param migrate_data: if not None, it is a dict which has data """ self._vmops.post_live_migration(ctxt, instance_ref, migrate_data)
**** CubicPower OpenStack Study **** def post_live_migration_at_destination(self, ctxt, instance_ref, network_info, block_migration, block_device_info=None): """Post operation of live migration at destination host. :param ctxt: security context :param instance_ref: nova.db.sqlalchemy.models.Instance object instance object that is migrated. :param network_info: instance network information :param : block_migration: if true, post operation of block_migration. """ self._vmops.post_live_migration_at_destination(ctxt, instance_ref, network_info, block_device_info, block_device_info)
**** CubicPower OpenStack Study **** def unfilter_instance(self, instance_ref, network_info): """Removes security groups configured for an instance.""" return self._vmops.unfilter_instance(instance_ref, network_info)
**** CubicPower OpenStack Study **** def refresh_security_group_rules(self, security_group_id): """Updates security group rules for all instances associated with a given security group. Invoked when security group rules are updated. """ return self._vmops.refresh_security_group_rules(security_group_id)
**** CubicPower OpenStack Study **** def refresh_security_group_members(self, security_group_id): """Updates security group rules for all instances associated with a given security group. Invoked when instances are added/removed to a security group. """ return self._vmops.refresh_security_group_members(security_group_id)
**** CubicPower OpenStack Study **** def refresh_instance_security_rules(self, instance): """Updates security group rules for specified instance. Invoked when instances are added/removed to a security group or when a rule is added/removed to a security group. """ return self._vmops.refresh_instance_security_rules(instance)
**** CubicPower OpenStack Study **** def refresh_provider_fw_rules(self): return self._vmops.refresh_provider_fw_rules()
**** CubicPower OpenStack Study **** def get_host_stats(self, refresh=False): """Return the current state of the host. If 'refresh' is True, run the update first. """ return self.host_state.get_host_stats(refresh=refresh)
**** CubicPower OpenStack Study **** def host_power_action(self, host, action): """The only valid values for 'action' on XenServer are 'reboot' or 'shutdown', even though the API also accepts 'startup'. As this is not technically possible on XenServer, since the host is the same physical machine as the hypervisor, if this is requested, we need to raise an exception. """ if action in ("reboot", "shutdown"): return self._host.host_power_action(host, action) else: msg = _("Host startup on XenServer is not supported.") raise NotImplementedError(msg)
**** CubicPower OpenStack Study **** def set_host_enabled(self, host, enabled): """Sets the specified host's ability to accept new instances.""" return self._host.set_host_enabled(host, enabled)
**** CubicPower OpenStack Study **** def get_host_uptime(self, host): """Returns the result of calling "uptime" on the target host.""" return self._host.get_host_uptime(host)
**** CubicPower OpenStack Study **** def host_maintenance_mode(self, host, mode): """Start/Stop host maintenance window. On start, it triggers guest VMs evacuation. """ return self._host.host_maintenance_mode(host, mode)
**** CubicPower OpenStack Study **** def add_to_aggregate(self, context, aggregate, host, **kwargs): """Add a compute host to an aggregate.""" return self._pool.add_to_aggregate(context, aggregate, host, **kwargs)
**** CubicPower OpenStack Study **** def remove_from_aggregate(self, context, aggregate, host, **kwargs): """Remove a compute host from an aggregate.""" return self._pool.remove_from_aggregate(context, aggregate, host, **kwargs)
**** CubicPower OpenStack Study **** def undo_aggregate_operation(self, context, op, aggregate, host, set_error=True): """Undo aggregate operation when pool error raised.""" return self._pool.undo_aggregate_operation(context, op, aggregate, host, set_error)
**** CubicPower OpenStack Study **** def resume_state_on_host_boot(self, context, instance, network_info, block_device_info=None): """resume guest state when a host is booted.""" self._vmops.power_on(instance)
**** CubicPower OpenStack Study **** def get_per_instance_usage(self): """Get information about instance resource usage. :returns: dict of nova uuid => dict of usage info """ return self._vmops.get_per_instance_usage()
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