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OpenStack Study: block_device.py**** CubicPower OpenStack Study ****
# Copyright 2011 Isaku Yamahata # All Rights Reserved. # # 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. import re from oslo.config import cfg from nova import exception from nova.openstack.common.gettextutils import _ from nova.openstack.common import log as logging from nova.openstack.common import strutils from nova import utils from nova.virt import driver CONF = cfg.CONF CONF.import_opt('default_ephemeral_format', 'nova.virt.driver') LOG = logging.getLogger(__name__) DEFAULT_ROOT_DEV_NAME = '/dev/sda1' _DEFAULT_MAPPINGS = {'ami': 'sda1', 'ephemeral0': 'sda2', 'root': DEFAULT_ROOT_DEV_NAME, 'swap': 'sda3'} bdm_legacy_fields = set(['device_name', 'delete_on_termination', 'virtual_name', 'snapshot_id', 'volume_id', 'volume_size', 'no_device', 'connection_info']) bdm_new_fields = set(['source_type', 'destination_type', 'guest_format', 'device_type', 'disk_bus', 'boot_index', 'device_name', 'delete_on_termination', 'snapshot_id', 'volume_id', 'volume_size', 'image_id', 'no_device', 'connection_info']) bdm_db_only_fields = set(['id', 'instance_uuid']) bdm_db_inherited_fields = set(['created_at', 'updated_at', 'deleted_at', 'deleted']) bdm_new_non_api_fields = set(['volume_id', 'snapshot_id', 'image_id', 'connection_info']) bdm_new_api_only_fields = set(['uuid']) bdm_new_api_fields = ((bdm_new_fields - bdm_new_non_api_fields) | bdm_new_api_only_fields)
**** CubicPower OpenStack Study **** class BlockDeviceDict(dict): """Represents a Block Device Mapping in Nova.""" _fields = bdm_new_fields _db_only_fields = (bdm_db_only_fields | bdm_db_inherited_fields) _required_fields = set(['source_type'])
**** CubicPower OpenStack Study **** def __init__(self, bdm_dict=None, do_not_default=None): super(BlockDeviceDict, self).__init__() bdm_dict = bdm_dict or {} do_not_default = do_not_default or set() self._validate(bdm_dict) # NOTE (ndipanov): Never default db fields self.update( dict((field, None) for field in self._fields - do_not_default)) self.update(list(bdm_dict.iteritems()))
**** CubicPower OpenStack Study **** def _validate(self, bdm_dict): """Basic data format validations.""" dict_fields = set(key for key, _ in bdm_dict.iteritems()) # Check that there are no bogus fields if not (dict_fields <= (self._fields | self._db_only_fields)): raise exception.InvalidBDMFormat( details="Some fields are invalid.") if bdm_dict.get('no_device'): return # Check that all required fields are there if (self._required_fields and not ((dict_fields & self._required_fields) == self._required_fields)): raise exception.InvalidBDMFormat( details="Some required fields are missing") if 'delete_on_termination' in bdm_dict: bdm_dict['delete_on_termination'] = strutils.bool_from_string( bdm_dict['delete_on_termination']) if bdm_dict.get('device_name') is not None: validate_device_name(bdm_dict['device_name']) validate_and_default_volume_size(bdm_dict) if bdm_dict.get('boot_index'): try: bdm_dict['boot_index'] = int(bdm_dict['boot_index']) except ValueError: raise exception.InvalidBDMFormat( details="Boot index is invalid.") @classmethod
**** CubicPower OpenStack Study **** def from_legacy(cls, legacy_bdm): copy_over_fields = bdm_legacy_fields & bdm_new_fields copy_over_fields |= (bdm_db_only_fields | bdm_db_inherited_fields) # NOTE (ndipanov): These fields cannot be computed # from legacy bdm, so do not default them # to avoid overwriting meaningful values in the db non_computable_fields = set(['boot_index', 'disk_bus', 'guest_format', 'device_type']) new_bdm = dict((fld, val) for fld, val in legacy_bdm.iteritems() if fld in copy_over_fields) virt_name = legacy_bdm.get('virtual_name') if is_swap_or_ephemeral(virt_name): new_bdm['source_type'] = 'blank' new_bdm['delete_on_termination'] = True new_bdm['destination_type'] = 'local' if virt_name == 'swap': new_bdm['guest_format'] = 'swap' else: new_bdm['guest_format'] = CONF.default_ephemeral_format elif legacy_bdm.get('snapshot_id'): new_bdm['source_type'] = 'snapshot' new_bdm['destination_type'] = 'volume' elif legacy_bdm.get('volume_id'): new_bdm['source_type'] = 'volume' new_bdm['destination_type'] = 'volume' elif legacy_bdm.get('no_device'): # NOTE (ndipanov): Just keep the BDM for now, pass else: raise exception.InvalidBDMFormat( details="Unrecognized legacy format.") return cls(new_bdm, non_computable_fields) @classmethod
**** CubicPower OpenStack Study **** def from_api(cls, api_dict): """Transform the API format of data to the internally used one. Only validate if the source_type field makes sense. """ if not api_dict.get('no_device'): source_type = api_dict.get('source_type') device_uuid = api_dict.get('uuid') if source_type not in ('volume', 'image', 'snapshot', 'blank'): raise exception.InvalidBDMFormat( details="Invalid source_type field.") elif source_type != 'blank': if not device_uuid: raise exception.InvalidBDMFormat( details="Missing device UUID.") api_dict[source_type + '_id'] = device_uuid api_dict.pop('uuid', None) return cls(api_dict)
**** CubicPower OpenStack Study **** def legacy(self): copy_over_fields = bdm_legacy_fields - set(['virtual_name']) copy_over_fields |= (bdm_db_only_fields | bdm_db_inherited_fields) legacy_block_device = dict((field, self.get(field)) for field in copy_over_fields if field in self) source_type = self.get('source_type') destination_type = self.get('destination_type') no_device = self.get('no_device') if source_type == 'blank': if self['guest_format'] == 'swap': legacy_block_device['virtual_name'] = 'swap' else: # NOTE (ndipanov): Always label as 0, it is up to # the calling routine to re-enumerate them legacy_block_device['virtual_name'] = 'ephemeral0' elif source_type in ('volume', 'snapshot') or no_device: legacy_block_device['virtual_name'] = None elif source_type == 'image': if destination_type != 'volume': # NOTE(ndipanov): Image bdms with local destination # have no meaning in the legacy format - raise raise exception.InvalidBDMForLegacy() legacy_block_device['virtual_name'] = None return legacy_block_device
**** CubicPower OpenStack Study **** def get_image_mapping(self): drop_fields = (set(['connection_info', 'device_name']) | self._db_only_fields) mapping_dict = dict(self) for fld in drop_fields: mapping_dict.pop(fld, None) return mapping_dict def is_safe_for_update(block_device_dict): """Determine if passed dict is a safe subset for update. Safe subset in this case means a safe subset of both legacy and new versions of data, that can be passed to an UPDATE query without any transformation. """ fields = set(block_device_dict.keys()) return fields <= (bdm_new_fields | bdm_db_inherited_fields | bdm_db_only_fields) def create_image_bdm(image_ref, boot_index=0): """Create a block device dict based on the image_ref. This is useful in the API layer to keep the compatibility with having an image_ref as a field in the instance requests """ return BlockDeviceDict( {'source_type': 'image', 'image_id': image_ref, 'delete_on_termination': True, 'boot_index': boot_index, 'device_type': 'disk', 'destination_type': 'local'}) def snapshot_from_bdm(snapshot_id, template): """Create a basic volume snapshot BDM from a given template bdm.""" copy_from_template = ['disk_bus', 'device_type', 'boot_index'] snapshot_dict = {'source_type': 'snapshot', 'destination_type': 'volume', 'snapshot_id': snapshot_id} for key in copy_from_template: snapshot_dict[key] = template.get(key) return BlockDeviceDict(snapshot_dict) def legacy_mapping(block_device_mapping): """Transform a list of block devices of an instance back to the legacy data format. """ legacy_block_device_mapping = [] for bdm in block_device_mapping: try: legacy_block_device = BlockDeviceDict(bdm).legacy() except exception.InvalidBDMForLegacy: continue legacy_block_device_mapping.append(legacy_block_device) # Re-enumerate the ephemeral devices for i, dev in enumerate(dev for dev in legacy_block_device_mapping if dev['virtual_name'] and is_ephemeral(dev['virtual_name'])): dev['virtual_name'] = dev['virtual_name'][:-1] + str(i) return legacy_block_device_mapping def from_legacy_mapping(legacy_block_device_mapping, image_uuid='', root_device_name=None, no_root=False): """Transform a legacy list of block devices to the new data format.""" new_bdms = [BlockDeviceDict.from_legacy(legacy_bdm) for legacy_bdm in legacy_block_device_mapping] # NOTE (ndipanov): We will not decide which device is root here - we assume # that it will be supplied later. This is useful for having the root device # as part of the image defined mappings that are already in the v2 format. if no_root: for bdm in new_bdms: bdm['boot_index'] = -1 return new_bdms image_bdm = None volume_backed = False # Try to assign boot_device if not root_device_name and not image_uuid: # NOTE (ndipanov): If there is no root_device, pick the first non # blank one. non_blank = [bdm for bdm in new_bdms if bdm['source_type'] != 'blank'] if non_blank: non_blank[0]['boot_index'] = 0 else: for bdm in new_bdms: if (bdm['source_type'] in ('volume', 'snapshot', 'image') and root_device_name is not None and (strip_dev(bdm.get('device_name')) == strip_dev(root_device_name))): bdm['boot_index'] = 0 volume_backed = True elif not bdm['no_device']: bdm['boot_index'] = -1 else: bdm['boot_index'] = None if not volume_backed and image_uuid: image_bdm = create_image_bdm(image_uuid, boot_index=0) return ([image_bdm] if image_bdm else []) + new_bdms def properties_root_device_name(properties): """get root device name from image meta data. If it isn't specified, return None. """ root_device_name = None # NOTE(yamahata): see image_service.s3.s3create() for bdm in properties.get('mappings', []): if bdm['virtual'] == 'root': root_device_name = bdm['device'] # NOTE(yamahata): register_image's command line can override # if 'root_device_name' in properties: root_device_name = properties['root_device_name'] return root_device_name def validate_device_name(value): try: # NOTE (ndipanov): Do not allow empty device names # until assigning default values # is supported by nova.compute utils.check_string_length(value, 'Device name', min_length=1, max_length=255) except exception.InvalidInput as e: raise exception.InvalidBDMFormat( details="Device name empty or too long.") if ' ' in value: raise exception.InvalidBDMFormat( details="Device name contains spaces.") def validate_and_default_volume_size(bdm): if bdm.get('volume_size'): try: bdm['volume_size'] = utils.validate_integer( bdm['volume_size'], 'volume_size', min_value=0) except exception.InvalidInput as e: raise exception.InvalidBDMFormat( details="Invalid volume_size.") _ephemeral = re.compile('^ephemeral(\d|[1-9]\d+)$') def is_ephemeral(device_name): return _ephemeral.match(device_name) is not None def ephemeral_num(ephemeral_name): assert is_ephemeral(ephemeral_name) return int(_ephemeral.sub('\\1', ephemeral_name)) def is_swap_or_ephemeral(device_name): return (device_name and (device_name == 'swap' or is_ephemeral(device_name))) def new_format_is_swap(bdm): if (bdm.get('source_type') == 'blank' and bdm.get('destination_type') == 'local' and bdm.get('guest_format') == 'swap'): return True return False def new_format_is_ephemeral(bdm): if (bdm.get('source_type') == 'blank' and not new_format_is_swap(bdm)): return True return False def get_root_bdm(bdms): try: return (bdm for bdm in bdms if bdm.get('boot_index', -1) == 0).next() except StopIteration: return None def mappings_prepend_dev(mappings): """Prepend '/dev/' to 'device' entry of swap/ephemeral virtual type.""" for m in mappings: virtual = m['virtual'] if (is_swap_or_ephemeral(virtual) and (not m['device'].startswith('/'))): m['device'] = '/dev/' + m['device'] return mappings _dev = re.compile('^/dev/') def strip_dev(device_name): """remove leading '/dev/'.""" return _dev.sub('', device_name) if device_name else device_name def prepend_dev(device_name): """Make sure there is a leading '/dev/'.""" return device_name and '/dev/' + strip_dev(device_name) _pref = re.compile('^((x?v|s)d)') def strip_prefix(device_name): """remove both leading /dev/ and xvd or sd or vd.""" device_name = strip_dev(device_name) return _pref.sub('', device_name) def instance_block_mapping(instance, bdms): root_device_name = instance['root_device_name'] # NOTE(clayg): remove this when xenapi is setting default_root_device if root_device_name is None: if driver.compute_driver_matches('xenapi.XenAPIDriver'): root_device_name = '/dev/xvda' else: return _DEFAULT_MAPPINGS mappings = {} mappings['ami'] = strip_dev(root_device_name) mappings['root'] = root_device_name default_ephemeral_device = instance.get('default_ephemeral_device') if default_ephemeral_device: mappings['ephemeral0'] = default_ephemeral_device default_swap_device = instance.get('default_swap_device') if default_swap_device: mappings['swap'] = default_swap_device ebs_devices = [] blanks = [] # 'ephemeralN', 'swap' and ebs for bdm in bdms: # ebs volume case if bdm.destination_type == 'volume': ebs_devices.append(bdm.device_name) continue if bdm.source_type == 'blank': blanks.append(bdm) # NOTE(yamahata): I'm not sure how ebs device should be numbered. # Right now sort by device name for deterministic # result. if ebs_devices: ebs_devices.sort() for nebs, ebs in enumerate(ebs_devices): mappings['ebs%d' % nebs] = ebs swap = [bdm for bdm in blanks if bdm.guest_format == 'swap'] if swap: mappings['swap'] = swap.pop().device_name ephemerals = [bdm for bdm in blanks if bdm.guest_format != 'swap'] if ephemerals: for num, eph in enumerate(ephemerals): mappings['ephemeral%d' % num] = eph.device_name return mappings def match_device(device): """Matches device name and returns prefix, suffix.""" match = re.match("(^/dev/x{0,1}[a-z]{0,1}d{0,1})([a-z]+)[0-9]*$", device) if not match: return None return match.groups() def volume_in_mapping(mount_device, block_device_info): block_device_list = [strip_dev(vol['mount_device']) for vol in driver.block_device_info_get_mapping( block_device_info)] swap = driver.block_device_info_get_swap(block_device_info) if driver.swap_is_usable(swap): block_device_list.append(strip_dev(swap['device_name'])) block_device_list += [strip_dev(ephemeral['device_name']) for ephemeral in driver.block_device_info_get_ephemerals( block_device_info)] LOG.debug(_("block_device_list %s"), block_device_list) return strip_dev(mount_device) in block_device_list
**** CubicPower OpenStack Study **** def is_safe_for_update(block_device_dict): """Determine if passed dict is a safe subset for update. Safe subset in this case means a safe subset of both legacy and new versions of data, that can be passed to an UPDATE query without any transformation. """ fields = set(block_device_dict.keys()) return fields <= (bdm_new_fields | bdm_db_inherited_fields | bdm_db_only_fields)
**** CubicPower OpenStack Study **** def create_image_bdm(image_ref, boot_index=0): """Create a block device dict based on the image_ref. This is useful in the API layer to keep the compatibility with having an image_ref as a field in the instance requests """ return BlockDeviceDict( {'source_type': 'image', 'image_id': image_ref, 'delete_on_termination': True, 'boot_index': boot_index, 'device_type': 'disk', 'destination_type': 'local'})
**** CubicPower OpenStack Study **** def snapshot_from_bdm(snapshot_id, template): """Create a basic volume snapshot BDM from a given template bdm.""" copy_from_template = ['disk_bus', 'device_type', 'boot_index'] snapshot_dict = {'source_type': 'snapshot', 'destination_type': 'volume', 'snapshot_id': snapshot_id} for key in copy_from_template: snapshot_dict[key] = template.get(key) return BlockDeviceDict(snapshot_dict)
**** CubicPower OpenStack Study **** def legacy_mapping(block_device_mapping): """Transform a list of block devices of an instance back to the legacy data format. """ legacy_block_device_mapping = [] for bdm in block_device_mapping: try: legacy_block_device = BlockDeviceDict(bdm).legacy() except exception.InvalidBDMForLegacy: continue legacy_block_device_mapping.append(legacy_block_device) # Re-enumerate the ephemeral devices for i, dev in enumerate(dev for dev in legacy_block_device_mapping if dev['virtual_name'] and is_ephemeral(dev['virtual_name'])): dev['virtual_name'] = dev['virtual_name'][:-1] + str(i) return legacy_block_device_mapping
**** CubicPower OpenStack Study **** def from_legacy_mapping(legacy_block_device_mapping, image_uuid='', root_device_name=None, no_root=False): """Transform a legacy list of block devices to the new data format.""" new_bdms = [BlockDeviceDict.from_legacy(legacy_bdm) for legacy_bdm in legacy_block_device_mapping] # NOTE (ndipanov): We will not decide which device is root here - we assume # that it will be supplied later. This is useful for having the root device # as part of the image defined mappings that are already in the v2 format. if no_root: for bdm in new_bdms: bdm['boot_index'] = -1 return new_bdms image_bdm = None volume_backed = False # Try to assign boot_device if not root_device_name and not image_uuid: # NOTE (ndipanov): If there is no root_device, pick the first non # blank one. non_blank = [bdm for bdm in new_bdms if bdm['source_type'] != 'blank'] if non_blank: non_blank[0]['boot_index'] = 0 else: for bdm in new_bdms: if (bdm['source_type'] in ('volume', 'snapshot', 'image') and root_device_name is not None and (strip_dev(bdm.get('device_name')) == strip_dev(root_device_name))): bdm['boot_index'] = 0 volume_backed = True elif not bdm['no_device']: bdm['boot_index'] = -1 else: bdm['boot_index'] = None if not volume_backed and image_uuid: image_bdm = create_image_bdm(image_uuid, boot_index=0) return ([image_bdm] if image_bdm else []) + new_bdms
**** CubicPower OpenStack Study **** def properties_root_device_name(properties): """get root device name from image meta data. If it isn't specified, return None. """ root_device_name = None # NOTE(yamahata): see image_service.s3.s3create() for bdm in properties.get('mappings', []): if bdm['virtual'] == 'root': root_device_name = bdm['device'] # NOTE(yamahata): register_image's command line can override # if 'root_device_name' in properties: root_device_name = properties['root_device_name'] return root_device_name
**** CubicPower OpenStack Study **** def validate_device_name(value): try: # NOTE (ndipanov): Do not allow empty device names # until assigning default values # is supported by nova.compute utils.check_string_length(value, 'Device name', min_length=1, max_length=255) except exception.InvalidInput as e: raise exception.InvalidBDMFormat( details="Device name empty or too long.") if ' ' in value: raise exception.InvalidBDMFormat( details="Device name contains spaces.")
**** CubicPower OpenStack Study **** def validate_and_default_volume_size(bdm): if bdm.get('volume_size'): try: bdm['volume_size'] = utils.validate_integer( bdm['volume_size'], 'volume_size', min_value=0) except exception.InvalidInput as e: raise exception.InvalidBDMFormat( details="Invalid volume_size.") _ephemeral = re.compile('^ephemeral(\d|[1-9]\d+)$')
**** CubicPower OpenStack Study **** def is_ephemeral(device_name): return _ephemeral.match(device_name) is not None
**** CubicPower OpenStack Study **** def ephemeral_num(ephemeral_name): assert is_ephemeral(ephemeral_name) return int(_ephemeral.sub('\\1', ephemeral_name))
**** CubicPower OpenStack Study **** def is_swap_or_ephemeral(device_name): return (device_name and (device_name == 'swap' or is_ephemeral(device_name)))
**** CubicPower OpenStack Study **** def new_format_is_swap(bdm): if (bdm.get('source_type') == 'blank' and bdm.get('destination_type') == 'local' and bdm.get('guest_format') == 'swap'): return True return False
**** CubicPower OpenStack Study **** def new_format_is_ephemeral(bdm): if (bdm.get('source_type') == 'blank' and not new_format_is_swap(bdm)): return True return False
**** CubicPower OpenStack Study **** def get_root_bdm(bdms): try: return (bdm for bdm in bdms if bdm.get('boot_index', -1) == 0).next() except StopIteration: return None
**** CubicPower OpenStack Study **** def mappings_prepend_dev(mappings): """Prepend '/dev/' to 'device' entry of swap/ephemeral virtual type.""" for m in mappings: virtual = m['virtual'] if (is_swap_or_ephemeral(virtual) and (not m['device'].startswith('/'))): m['device'] = '/dev/' + m['device'] return mappings _dev = re.compile('^/dev/')
**** CubicPower OpenStack Study **** def strip_dev(device_name): """remove leading '/dev/'.""" return _dev.sub('', device_name) if device_name else device_name
**** CubicPower OpenStack Study **** def prepend_dev(device_name): """Make sure there is a leading '/dev/'.""" return device_name and '/dev/' + strip_dev(device_name) _pref = re.compile('^((x?v|s)d)')
**** CubicPower OpenStack Study **** def strip_prefix(device_name): """remove both leading /dev/ and xvd or sd or vd.""" device_name = strip_dev(device_name) return _pref.sub('', device_name)
**** CubicPower OpenStack Study **** def instance_block_mapping(instance, bdms): root_device_name = instance['root_device_name'] # NOTE(clayg): remove this when xenapi is setting default_root_device if root_device_name is None: if driver.compute_driver_matches('xenapi.XenAPIDriver'): root_device_name = '/dev/xvda' else: return _DEFAULT_MAPPINGS mappings = {} mappings['ami'] = strip_dev(root_device_name) mappings['root'] = root_device_name default_ephemeral_device = instance.get('default_ephemeral_device') if default_ephemeral_device: mappings['ephemeral0'] = default_ephemeral_device default_swap_device = instance.get('default_swap_device') if default_swap_device: mappings['swap'] = default_swap_device ebs_devices = [] blanks = [] # 'ephemeralN', 'swap' and ebs for bdm in bdms: # ebs volume case if bdm.destination_type == 'volume': ebs_devices.append(bdm.device_name) continue if bdm.source_type == 'blank': blanks.append(bdm) # NOTE(yamahata): I'm not sure how ebs device should be numbered. # Right now sort by device name for deterministic # result. if ebs_devices: ebs_devices.sort() for nebs, ebs in enumerate(ebs_devices): mappings['ebs%d' % nebs] = ebs swap = [bdm for bdm in blanks if bdm.guest_format == 'swap'] if swap: mappings['swap'] = swap.pop().device_name ephemerals = [bdm for bdm in blanks if bdm.guest_format != 'swap'] if ephemerals: for num, eph in enumerate(ephemerals): mappings['ephemeral%d' % num] = eph.device_name return mappings
**** CubicPower OpenStack Study **** def match_device(device): """Matches device name and returns prefix, suffix.""" match = re.match("(^/dev/x{0,1}[a-z]{0,1}d{0,1})([a-z]+)[0-9]*$", device) if not match: return None return match.groups()
**** CubicPower OpenStack Study **** def volume_in_mapping(mount_device, block_device_info): block_device_list = [strip_dev(vol['mount_device']) for vol in driver.block_device_info_get_mapping( block_device_info)] swap = driver.block_device_info_get_swap(block_device_info) if driver.swap_is_usable(swap): block_device_list.append(strip_dev(swap['device_name'])) block_device_list += [strip_dev(ephemeral['device_name']) for ephemeral in driver.block_device_info_get_ephemerals( block_device_info)] LOG.debug(_("block_device_list %s"), block_device_list) return strip_dev(mount_device) in block_device_list
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