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OpenStack Study: ceph.py**** CubicPower OpenStack Study ****
# Copyright 2013 Canonical Ltd. # 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. """Ceph Backup Service Implementation. This driver supports backing up volumes of any type to a Ceph object store. It is also capable of detecting whether the volume to be backed up is a Ceph RBD volume and, if so, attempts to perform incremental/differential backups. Support is also included for the following in the case of a source volume being a Ceph RBD volume: * backing up within the same Ceph pool (not recommended) * backing up between different Ceph pools * backing up between different Ceph clusters At the time of writing, differential backup support in Ceph/librbd was quite new so this driver accounts for this by first attempting differential backup and falling back to full backup/copy if the former fails. It is recommended that you upgrade to Ceph Dumpling (>= v0.67) or above to get the best results. If incremental backups are used, multiple backups of the same volume are stored as snapshots so that minimal space is consumed in the object store and restoring the volume takes a far reduced amount of time compared to a full copy. Note that Cinder supports restoring to a new volume or the original volume the backup was taken from. For the latter case, a full copy is enforced since this was deemed the safest action to take. It is therefore recommended to always restore to a new volume (default). """ import eventlet import fcntl import os import re import subprocess import time from oslo.config import cfg from cinder.backup.driver import BackupDriver from cinder import exception from cinder.openstack.common import log as logging from cinder.openstack.common import strutils from cinder import units from cinder import utils import cinder.volume.drivers.rbd as rbd_driver try: import rados import rbd except ImportError: rados = None rbd = None LOG = logging.getLogger(__name__) service_opts = [ cfg.StrOpt('backup_ceph_conf', default='/etc/ceph/ceph.conf', help='Ceph configuration file to use.'), cfg.StrOpt('backup_ceph_user', default='cinder', help='The Ceph user to connect with. Default here is to use ' 'the same user as for Cinder volumes. If not using cephx ' 'this should be set to None.'), cfg.IntOpt('backup_ceph_chunk_size', default=(units.MiB * 128), help='The chunk size, in bytes, that a backup is broken into ' 'before transfer to the Ceph object store.'), cfg.StrOpt('backup_ceph_pool', default='backups', help='The Ceph pool where volume backups are stored.'), cfg.IntOpt('backup_ceph_stripe_unit', default=0, help='RBD stripe unit to use when creating a backup image.'), cfg.IntOpt('backup_ceph_stripe_count', default=0, help='RBD stripe count to use when creating a backup image.'), cfg.BoolOpt('restore_discard_excess_bytes', default=True, help='If True, always discard excess bytes when restoring ' 'volumes i.e. pad with zeroes.') ] CONF = cfg.CONF CONF.register_opts(service_opts)
**** CubicPower OpenStack Study **** class VolumeMetadataBackup(object):
**** CubicPower OpenStack Study **** def __init__(self, client, backup_id): self._client = client self._backup_id = backup_id @property
**** CubicPower OpenStack Study **** def name(self): return strutils.safe_encode("backup.%s.meta" % (self._backup_id)) @property
**** CubicPower OpenStack Study **** def exists(self): meta_obj = rados.Object(self._client.ioctx, self.name) return self._exists(meta_obj)
**** CubicPower OpenStack Study **** def _exists(self, obj): try: obj.stat() except rados.ObjectNotFound: return False else: return True
**** CubicPower OpenStack Study **** def set(self, json_meta): """Write JSON metadata to a new object. This should only be called once per backup. Raises VolumeMetadataBackupExists if the object already exists. """ meta_obj = rados.Object(self._client.ioctx, self.name) if self._exists(meta_obj): msg = _("Metadata backup object '%s' already exists") % (self.name) raise exception.VolumeMetadataBackupExists(msg) meta_obj.write(json_meta)
**** CubicPower OpenStack Study **** def get(self): """Get metadata backup object. Returns None if the object does not exist. """ meta_obj = rados.Object(self._client.ioctx, self.name) if not self._exists(meta_obj): msg = _("Metadata backup object %s does not exist") % (self.name) LOG.debug(msg) return None return meta_obj.read()
**** CubicPower OpenStack Study **** def remove_if_exists(self): meta_obj = rados.Object(self._client.ioctx, self.name) try: meta_obj.remove() except rados.ObjectNotFound: msg = (_("Metadata backup object '%s' not found - ignoring") % (self.name)) LOG.debug(msg)
**** CubicPower OpenStack Study **** class CephBackupDriver(BackupDriver): """Backup Cinder volumes to Ceph Object Store. This class enables backing up Cinder volumes to a Ceph object store. Backups may be stored in their own pool or even cluster. Store location is
**** CubicPower OpenStack Study **** def __init__(self, context, db_driver=None, execute=None): super(CephBackupDriver, self).__init__(context, db_driver) self.rbd = rbd self.rados = rados self.chunk_size = CONF.backup_ceph_chunk_size self._execute = execute or utils.execute if self._supports_stripingv2: self.rbd_stripe_unit = CONF.backup_ceph_stripe_unit self.rbd_stripe_count = CONF.backup_ceph_stripe_count else: LOG.info(_("RBD striping not supported - ignoring configuration " "settings for rbd striping")) self.rbd_stripe_count = 0 self.rbd_stripe_unit = 0 self._ceph_backup_user = strutils.safe_encode(CONF.backup_ceph_user) self._ceph_backup_pool = strutils.safe_encode(CONF.backup_ceph_pool) self._ceph_backup_conf = strutils.safe_encode(CONF.backup_ceph_conf)
**** CubicPower OpenStack Study **** def _validate_string_args(self, *args): """Ensure all args are non-None and non-empty.""" return all(args)
**** CubicPower OpenStack Study **** def _ceph_args(self, user, conf=None, pool=None): """Create default ceph args for executing rbd commands. If no --conf is provided, rbd will look in the default locations e.g. /etc/ceph/ceph.conf """ # Make sure user arg is valid since rbd command may not fail if # invalid/no user provided, resulting in unexpected behaviour. if not self._validate_string_args(user): raise exception.BackupInvalidCephArgs(_("invalid user '%s'") % (user)) args = ['--id', user] if conf: args.extend(['--conf', conf]) if pool: args.extend(['--pool', pool]) return args @property
**** CubicPower OpenStack Study **** def _supports_layering(self): """Determine if copy-on-write is supported by our version of librbd.""" return hasattr(self.rbd, 'RBD_FEATURE_LAYERING') @property
**** CubicPower OpenStack Study **** def _supports_stripingv2(self): """Determine if striping is supported by our version of librbd.""" return hasattr(self.rbd, 'RBD_FEATURE_STRIPINGV2')
**** CubicPower OpenStack Study **** def _get_rbd_support(self): """Determine RBD features supported by our version of librbd.""" old_format = True features = 0 if self._supports_layering: old_format = False features |= self.rbd.RBD_FEATURE_LAYERING if self._supports_stripingv2: old_format = False features |= self.rbd.RBD_FEATURE_STRIPINGV2 return (old_format, features)
**** CubicPower OpenStack Study **** def _connect_to_rados(self, pool=None): """Establish connection to the backup Ceph cluster.""" client = self.rados.Rados(rados_id=self._ceph_backup_user, conffile=self._ceph_backup_conf) try: client.connect() pool_to_open = strutils.safe_encode(pool or self._ceph_backup_pool) ioctx = client.open_ioctx(pool_to_open) return client, ioctx except self.rados.Error: # shutdown cannot raise an exception client.shutdown() raise
**** CubicPower OpenStack Study **** def _disconnect_from_rados(self, client, ioctx): """Terminate connection with the backup Ceph cluster.""" # closing an ioctx cannot raise an exception ioctx.close() client.shutdown()
**** CubicPower OpenStack Study **** def _get_backup_base_name(self, volume_id, backup_id=None, diff_format=False): """Return name of base image used for backup. Incremental backups use a new base name so we support old and new style format. """ # Ensure no unicode if diff_format: return strutils.safe_encode("volume-%s.backup.base" % (volume_id)) else: if backup_id is None: msg = _("Backup id required") raise exception.InvalidParameterValue(msg) return strutils.safe_encode("volume-%s.backup.%s" % (volume_id, backup_id))
**** CubicPower OpenStack Study **** def _discard_bytes(self, volume, offset, length): """Trim length bytes from offset. If the volume is an rbd do a discard() otherwise assume it is a file and pad with zeroes. """ if length: LOG.debug(_("Discarding %(length)s bytes from offset %(offset)s") % {'length': length, 'offset': offset}) if self._file_is_rbd(volume): volume.rbd_image.discard(offset, length) else: zeroes = '\0' * length chunks = int(length / self.chunk_size) for chunk in xrange(0, chunks): LOG.debug(_("Writing zeroes chunk %d") % (chunk)) volume.write(zeroes) volume.flush() # yield to any other pending backups eventlet.sleep(0) rem = int(length % self.chunk_size) if rem: zeroes = '\0' * rem volume.write(zeroes) volume.flush()
**** CubicPower OpenStack Study **** def _transfer_data(self, src, src_name, dest, dest_name, length): """Transfer data between files (Python IO objects).""" LOG.debug(_("Transferring data between '%(src)s' and '%(dest)s'") % {'src': src_name, 'dest': dest_name}) chunks = int(length / self.chunk_size) LOG.debug(_("%(chunks)s chunks of %(bytes)s bytes to be transferred") % {'chunks': chunks, 'bytes': self.chunk_size}) for chunk in xrange(0, chunks): before = time.time() data = src.read(self.chunk_size) # If we have reach end of source, discard any extraneous bytes from # destination volume if trim is enabled and stop writing. if data == '': if CONF.restore_discard_excess_bytes: self._discard_bytes(dest, dest.tell(), length - dest.tell()) return dest.write(data) dest.flush() delta = (time.time() - before) rate = (self.chunk_size / delta) / 1024 LOG.debug((_("Transferred chunk %(chunk)s of %(chunks)s " "(%(rate)dK/s)") % {'chunk': chunk + 1, 'chunks': chunks, 'rate': rate})) # yield to any other pending backups eventlet.sleep(0) rem = int(length % self.chunk_size) if rem: LOG.debug(_("Transferring remaining %s bytes") % (rem)) data = src.read(rem) if data == '': if CONF.restore_discard_excess_bytes: self._discard_bytes(dest, dest.tell(), rem) else: dest.write(data) dest.flush() # yield to any other pending backups eventlet.sleep(0)
**** CubicPower OpenStack Study **** def _create_base_image(self, name, size, rados_client): """Create a base backup image. This will be the base image used for storing differential exports. """ LOG.debug(_("Creating base image '%s'") % (name)) old_format, features = self._get_rbd_support() self.rbd.RBD().create(ioctx=rados_client.ioctx, name=name, size=size, old_format=old_format, features=features, stripe_unit=self.rbd_stripe_unit, stripe_count=self.rbd_stripe_count)
**** CubicPower OpenStack Study **** def _delete_backup_snapshot(self, rados_client, base_name, backup_id): """Delete snapshot associated with this backup if one exists. A backup should have at most ONE associated snapshot. This is required before attempting to delete the base image. The snapshot on the original volume can be left as it will be purged when the volume is deleted. Returns tuple(deleted_snap_name, num_of_remaining_snaps). """ remaining_snaps = 0 base_rbd = self.rbd.Image(rados_client.ioctx, base_name) try: snap_name = self._get_backup_snap_name(base_rbd, base_name, backup_id) if snap_name: LOG.debug(_("Deleting backup snapshot='%s'") % (snap_name)) base_rbd.remove_snap(snap_name) else: LOG.debug(_("No backup snapshot to delete")) # Now check whether any snapshots remain on the base image backup_snaps = self.get_backup_snaps(base_rbd) if backup_snaps: remaining_snaps = len(backup_snaps) finally: base_rbd.close() return snap_name, remaining_snaps
**** CubicPower OpenStack Study **** def _try_delete_base_image(self, backup_id, volume_id, base_name=None): """Try to delete backup RBD image. If the rbd image is a base image for incremental backups, it may have snapshots. Delete the snapshot associated with backup_id and if the image has no more snapshots, delete it. Otherwise return. If no base name is provided try normal (full) format then diff format image name. If a base name is provided but does not exist, ImageNotFound will be raised. If the image is busy, a number of retries will be performed if ImageBusy is received, after which the exception will be propagated to the caller. """ retries = 3 delay = 5 try_diff_format = False if base_name is None: try_diff_format = True base_name = self._get_backup_base_name(volume_id, backup_id) LOG.debug(_("Trying diff format name format basename='%s'") % (base_name)) with rbd_driver.RADOSClient(self) as client: rbd_exists, base_name = \ self._rbd_image_exists(base_name, volume_id, client, try_diff_format=try_diff_format) if not rbd_exists: raise self.rbd.ImageNotFound(_("image %s not found") % (base_name)) while retries >= 0: # First delete associated snapshot from base image (if exists) snap, rem = self._delete_backup_snapshot(client, base_name, backup_id) if rem: msg = (_("Base image still has %s snapshots so skipping " "base image delete") % (rem)) LOG.info(msg) return LOG.info(_("Deleting base image='%s'") % (base_name)) # Delete base if no more snapshots try: self.rbd.RBD().remove(client.ioctx, base_name) except self.rbd.ImageBusy as exc: # Allow a retry if the image is busy if retries > 0: LOG.info((_("Image busy, retrying %(retries)s " "more time(s) in %(delay)ss") % {'retries': retries, 'delay': delay})) eventlet.sleep(delay) else: LOG.error(_("Max retries reached - raising error")) raise exc else: LOG.debug(_("Base backup image='%s' deleted)") % (base_name)) retries = 0 finally: retries -= 1 # Since we have deleted the base image we can delete the source # volume backup snapshot. src_name = strutils.safe_encode(volume_id) if src_name in self.rbd.RBD().list(client.ioctx): LOG.debug(_("Deleting source snapshot '%s'") % snap) src_rbd = self.rbd.Image(client.ioctx, src_name) try: src_rbd.remove_snap(snap) finally: src_rbd.close()
**** CubicPower OpenStack Study **** def _piped_execute(self, cmd1, cmd2): """Pipe output of cmd1 into cmd2.""" LOG.debug("Piping cmd1='%s' into..." % (' '.join(cmd1))) LOG.debug("cmd2='%s'" % (' '.join(cmd2))) try: p1 = subprocess.Popen(cmd1, stdout=subprocess.PIPE, stderr=subprocess.PIPE) except OSError as e: LOG.error("Pipe1 failed - %s " % unicode(e)) raise # NOTE(dosaboy): ensure that the pipe is blocking. This is to work # around the case where evenlet.green.subprocess is used which seems to # use a non-blocking pipe. flags = fcntl.fcntl(p1.stdout, fcntl.F_GETFL) & (~os.O_NONBLOCK) fcntl.fcntl(p1.stdout, fcntl.F_SETFL, flags) try: p2 = subprocess.Popen(cmd2, stdin=p1.stdout, stdout=subprocess.PIPE, stderr=subprocess.PIPE) except OSError as e: LOG.error("Pipe2 failed - %s " % unicode(e)) raise p1.stdout.close() stdout, stderr = p2.communicate() return p2.returncode, stderr
**** CubicPower OpenStack Study **** def _rbd_diff_transfer(self, src_name, src_pool, dest_name, dest_pool, src_user, src_conf, dest_user, dest_conf, src_snap=None, from_snap=None): """Copy only extents changed between two points. If no snapshot is provided, the diff extents will be all those changed since the rbd volume/base was created, otherwise it will be those changed since the snapshot was created. """ LOG.debug(_("Performing differential transfer from '%(src)s' to " "'%(dest)s'") % {'src': src_name, 'dest': dest_name}) # NOTE(dosaboy): Need to be tolerant of clusters/clients that do # not support these operations since at the time of writing they # were very new. src_ceph_args = self._ceph_args(src_user, src_conf, pool=src_pool) dest_ceph_args = self._ceph_args(dest_user, dest_conf, pool=dest_pool) cmd1 = ['rbd', 'export-diff'] + src_ceph_args if from_snap is not None: cmd1.extend(['--from-snap', from_snap]) if src_snap: path = strutils.safe_encode("%s/%s@%s" % (src_pool, src_name, src_snap)) else: path = strutils.safe_encode("%s/%s" % (src_pool, src_name)) cmd1.extend([path, '-']) cmd2 = ['rbd', 'import-diff'] + dest_ceph_args rbd_path = strutils.safe_encode("%s/%s" % (dest_pool, dest_name)) cmd2.extend(['-', rbd_path]) ret, stderr = self._piped_execute(cmd1, cmd2) if ret: msg = (_("RBD diff op failed - (ret=%(ret)s stderr=%(stderr)s)") % ({'ret': ret, 'stderr': stderr})) LOG.info(msg) raise exception.BackupRBDOperationFailed(msg)
**** CubicPower OpenStack Study **** def _rbd_image_exists(self, name, volume_id, client, try_diff_format=False): """Return tuple (exists, name).""" rbds = self.rbd.RBD().list(client.ioctx) if name not in rbds: msg = _("Image '%s' not found - trying diff format name") % (name) LOG.debug(msg) if try_diff_format: name = self._get_backup_base_name(volume_id, diff_format=True) if name not in rbds: msg = _("Diff format image '%s' not found") % (name) LOG.debug(msg) return False, name else: return False, name return True, name
**** CubicPower OpenStack Study **** def _snap_exists(self, base_name, snap_name, client): """Return True if snapshot exists in base image.""" base_rbd = self.rbd.Image(client.ioctx, base_name, read_only=True) try: snaps = base_rbd.list_snaps() finally: base_rbd.close() if snaps is None: return False for snap in snaps: if snap['name'] == snap_name: return True return False
**** CubicPower OpenStack Study **** def _backup_rbd(self, backup_id, volume_id, volume_file, volume_name, length): """Create a incremental backup from an RBD image.""" rbd_user = volume_file.rbd_user rbd_pool = volume_file.rbd_pool rbd_conf = volume_file.rbd_conf source_rbd_image = volume_file.rbd_image # Identify our --from-snap point (if one exists) from_snap = self._get_most_recent_snap(source_rbd_image) LOG.debug(_("Using --from-snap '%s'") % from_snap) base_name = self._get_backup_base_name(volume_id, diff_format=True) image_created = False with rbd_driver.RADOSClient(self, self._ceph_backup_pool) as client: # If from_snap does not exist at the destination (and the # destination exists), this implies a previous backup has failed. # In this case we will force a full backup. # # TODO(dosaboy): find a way to repair the broken backup # if base_name not in self.rbd.RBD().list(ioctx=client.ioctx): # If a from_snap is defined but the base does not exist, we # ignore it since it is stale and waiting to be cleaned up. if from_snap: LOG.debug(_("Source snapshot '%s' is stale so deleting") % (from_snap)) source_rbd_image.remove_snap(from_snap) from_snap = None # Create new base image self._create_base_image(base_name, length, client) image_created = True else: # If a from_snap is defined but does not exist in the back base # then we cannot proceed (see above) if not self._snap_exists(base_name, from_snap, client): errmsg = (_("Snapshot='%(snap)s' does not exist in base " "image='%(base)s' - aborting incremental " "backup") % {'snap': from_snap, 'base': base_name}) LOG.info(errmsg) # Raise this exception so that caller can try another # approach raise exception.BackupRBDOperationFailed(errmsg) # Snapshot source volume so that we have a new point-in-time new_snap = self._get_new_snap_name(backup_id) LOG.debug(_("Creating backup snapshot='%s'") % (new_snap)) source_rbd_image.create_snap(new_snap) # Attempt differential backup. If this fails, perhaps because librbd # or Ceph cluster version does not support it, do a full backup # instead. # # TODO(dosaboy): find a way to determine if the operation is supported # rather than brute force approach. try: before = time.time() self._rbd_diff_transfer(volume_name, rbd_pool, base_name, self._ceph_backup_pool, src_user=rbd_user, src_conf=rbd_conf, dest_user=self._ceph_backup_user, dest_conf=self._ceph_backup_conf, src_snap=new_snap, from_snap=from_snap) LOG.debug(_("Differential backup transfer completed in %.4fs") % (time.time() - before)) # We don't need the previous snapshot (if there was one) anymore so # delete it. if from_snap: source_rbd_image.remove_snap(from_snap) except exception.BackupRBDOperationFailed: LOG.debug(_("Differential backup transfer failed")) # Clean up if image was created as part of this operation if image_created: self._try_delete_base_image(backup_id, volume_id, base_name=base_name) # Delete snapshot LOG.debug(_("Deleting backup snapshot='%s'") % (new_snap)) source_rbd_image.remove_snap(new_snap) # Re-raise the exception so that caller can try another approach raise
**** CubicPower OpenStack Study **** def _file_is_rbd(self, volume_file): """Returns True if the volume_file is actually an RBD image.""" return hasattr(volume_file, 'rbd_image')
**** CubicPower OpenStack Study **** def _full_backup(self, backup_id, volume_id, src_volume, src_name, length): """Perform a full backup of src volume. First creates a base backup image in our backup location then performs an chunked copy of all data from source volume to a new backup rbd image. """ backup_name = self._get_backup_base_name(volume_id, backup_id) with rbd_driver.RADOSClient(self, self._ceph_backup_pool) as client: # First create base backup image old_format, features = self._get_rbd_support() LOG.debug(_("Creating base image='%s'") % (backup_name)) self.rbd.RBD().create(ioctx=client.ioctx, name=backup_name, size=length, old_format=old_format, features=features, stripe_unit=self.rbd_stripe_unit, stripe_count=self.rbd_stripe_count) LOG.debug(_("Copying data")) dest_rbd = self.rbd.Image(client.ioctx, backup_name) try: rbd_meta = rbd_driver.RBDImageMetadata(dest_rbd, self._ceph_backup_pool, self._ceph_backup_user, self._ceph_backup_conf) rbd_fd = rbd_driver.RBDImageIOWrapper(rbd_meta) self._transfer_data(src_volume, src_name, rbd_fd, backup_name, length) finally: dest_rbd.close() @staticmethod
**** CubicPower OpenStack Study **** def backup_snapshot_name_pattern(): """Returns the pattern used to match backup snapshots. It is essential that snapshots created for purposes other than backups do not have this name format. """ return r"^backup\.([a-z0-9\-]+?)\.snap\.(.+)$" @classmethod
**** CubicPower OpenStack Study **** def get_backup_snaps(cls, rbd_image, sort=False): """Get all backup snapshots for the given rbd image. NOTE: this call is made public since these snapshots must be deleted before the base volume can be deleted. """ snaps = rbd_image.list_snaps() backup_snaps = [] for snap in snaps: search_key = cls.backup_snapshot_name_pattern() result = re.search(search_key, snap['name']) if result: backup_snaps.append({'name': result.group(0), 'backup_id': result.group(1), 'timestamp': result.group(2)}) if sort: # Sort into ascending order of timestamp backup_snaps.sort(key=lambda x: x['timestamp'], reverse=True) return backup_snaps
**** CubicPower OpenStack Study **** def _get_new_snap_name(self, backup_id): return strutils.safe_encode("backup.%s.snap.%s" % (backup_id, time.time()))
**** CubicPower OpenStack Study **** def _get_backup_snap_name(self, rbd_image, name, backup_id): """Return the name of the snapshot associated with backup_id. The rbd image provided must be the base image used for an incremental backup. A backup is only allowed ONE associated snapshot. If more are found, exception.BackupOperationError is raised. """ snaps = self.get_backup_snaps(rbd_image) LOG.debug(_("Looking for snapshot of backup base '%s'") % (name)) if not snaps: LOG.debug(_("Backup base '%s' has no snapshots") % (name)) return None snaps = [snap['name'] for snap in snaps if snap['backup_id'] == backup_id] if not snaps: LOG.debug(_("Backup '%s' has no snapshot") % (backup_id)) return None if len(snaps) > 1: msg = (_("Backup should only have one snapshot but instead has %s") % (len(snaps))) LOG.error(msg) raise exception.BackupOperationError(msg) LOG.debug(_("Found snapshot '%s'") % (snaps[0])) return snaps[0]
**** CubicPower OpenStack Study **** def _get_most_recent_snap(self, rbd_image): """Get the most recent backup snapshot of the provided image. Returns name of most recent backup snapshot or None if there are no backup snapshots. """ backup_snaps = self.get_backup_snaps(rbd_image, sort=True) if not backup_snaps: return None return backup_snaps[0]['name']
**** CubicPower OpenStack Study **** def _get_volume_size_gb(self, volume): """Return the size in gigabytes of the given volume. Raises exception.InvalidParameterValue if volume size is 0. """ if int(volume['size']) == 0: errmsg = _("Need non-zero volume size") raise exception.InvalidParameterValue(errmsg) return int(volume['size']) * units.GiB
**** CubicPower OpenStack Study **** def _backup_metadata(self, backup): """Backup volume metadata. NOTE(dosaboy): the metadata we are backing up is obtained from a versioned api so we should not alter it in any way here. We must also be sure that the service that will perform the restore is compatible with version used. """ json_meta = self.get_metadata(backup['volume_id']) if not json_meta: LOG.debug("No volume metadata to backup") return LOG.debug("Backing up volume metadata") try: with rbd_driver.RADOSClient(self) as client: vol_meta_backup = VolumeMetadataBackup(client, backup['id']) vol_meta_backup.set(json_meta) except exception.VolumeMetadataBackupExists as e: msg = (_("Failed to backup volume metadata - %s") % (e)) raise exception.BackupOperationError(msg)
**** CubicPower OpenStack Study **** def backup(self, backup, volume_file, backup_metadata=True): """Backup volume and metadata (if available) to Ceph object store. If the source volume is an RBD we will attempt to do an incremental/differential backup, otherwise a full copy is performed. If this fails we will attempt to fall back to full copy. """ backup_id = backup['id'] volume = self.db.volume_get(self.context, backup['volume_id']) volume_id = volume['id'] volume_name = volume['name'] LOG.debug(_("Starting backup of volume='%s'") % volume_name) # Ensure we are at the beginning of the volume volume_file.seek(0) length = self._get_volume_size_gb(volume) do_full_backup = False if self._file_is_rbd(volume_file): # If volume an RBD, attempt incremental backup. try: self._backup_rbd(backup_id, volume_id, volume_file, volume_name, length) except exception.BackupRBDOperationFailed: LOG.debug(_("Forcing full backup")) do_full_backup = True else: do_full_backup = True if do_full_backup: self._full_backup(backup_id, volume_id, volume_file, volume_name, length) self.db.backup_update(self.context, backup_id, {'container': self._ceph_backup_pool}) if backup_metadata: try: self._backup_metadata(backup) except exception.BackupOperationError: # Cleanup. self.delete(backup) raise LOG.debug(_("Backup '%s' finished.") % (backup_id))
**** CubicPower OpenStack Study **** def _full_restore(self, backup_id, volume_id, dest_file, dest_name, length, src_snap=None): """Restore volume using full copy i.e. all extents. This will result in all extents being copied from source to destination. """ with rbd_driver.RADOSClient(self, self._ceph_backup_pool) as client: # If a source snapshot is provided we assume the base is diff # format. if src_snap: diff_format = True else: diff_format = False backup_name = self._get_backup_base_name(volume_id, backup_id=backup_id, diff_format=diff_format) # Retrieve backup volume src_rbd = self.rbd.Image(client.ioctx, backup_name, snapshot=src_snap, read_only=True) try: rbd_meta = rbd_driver.RBDImageMetadata(src_rbd, self._ceph_backup_pool, self._ceph_backup_user, self._ceph_backup_conf) rbd_fd = rbd_driver.RBDImageIOWrapper(rbd_meta) self._transfer_data(rbd_fd, backup_name, dest_file, dest_name, length) finally: src_rbd.close()
**** CubicPower OpenStack Study **** def _check_restore_vol_size(self, backup_base, restore_vol, restore_length, src_pool): """Ensure that the restore volume is the correct size. If the restore volume was bigger than the backup, the diff restore will shrink it to the size of the original backup so we need to post-process and resize it back to its expected size. """ with rbd_driver.RADOSClient(self, self._ceph_backup_pool) as client: adjust_size = 0 base_image = self.rbd.Image(client.ioctx, strutils.safe_encode(backup_base), read_only=True) try: if restore_length != base_image.size(): adjust_size = restore_length finally: base_image.close() if adjust_size: with rbd_driver.RADOSClient(self, src_pool) as client: dest_image = self.rbd.Image(client.ioctx, strutils.safe_encode(restore_vol)) try: LOG.debug(_("Adjusting restore vol size")) dest_image.resize(adjust_size) finally: dest_image.close()
**** CubicPower OpenStack Study **** def _diff_restore_rbd(self, base_name, restore_file, restore_name, restore_point, restore_length): """Attempt restore rbd volume from backup using diff transfer.""" rbd_user = restore_file.rbd_user rbd_pool = restore_file.rbd_pool rbd_conf = restore_file.rbd_conf LOG.debug(_("Attempting incremental restore from base='%(base)s' " "snap='%(snap)s'") % {'base': base_name, 'snap': restore_point}) before = time.time() try: self._rbd_diff_transfer(base_name, self._ceph_backup_pool, restore_name, rbd_pool, src_user=self._ceph_backup_user, src_conf=self._ceph_backup_conf, dest_user=rbd_user, dest_conf=rbd_conf, src_snap=restore_point) except exception.BackupRBDOperationFailed: LOG.exception(_("Differential restore failed, trying full " "restore")) raise # If the volume we are restoring to is larger than the backup volume, # we will need to resize it after the diff import since import-diff # appears to shrink the target rbd volume to the size of the original # backup volume. self._check_restore_vol_size(base_name, restore_name, restore_length, rbd_pool) LOG.debug(_("Restore transfer completed in %.4fs") % (time.time() - before))
**** CubicPower OpenStack Study **** def _num_backup_snaps(self, backup_base_name): """Return the number of snapshots that exist on the base image.""" with rbd_driver.RADOSClient(self, self._ceph_backup_pool) as client: base_rbd = self.rbd.Image(client.ioctx, backup_base_name, read_only=True) try: snaps = self.get_backup_snaps(base_rbd) finally: base_rbd.close() if snaps: return len(snaps) else: return 0
**** CubicPower OpenStack Study **** def _get_restore_point(self, base_name, backup_id): """Get restore point snapshot name for incremental backup. If the backup was not incremental (determined by the fact that the base has no snapshots/restore points), None is returned. Otherwise, the restore point associated with backup_id is returned. """ with rbd_driver.RADOSClient(self, self._ceph_backup_pool) as client: base_rbd = self.rbd.Image(client.ioctx, base_name, read_only=True) try: restore_point = self._get_backup_snap_name(base_rbd, base_name, backup_id) finally: base_rbd.close() return restore_point
**** CubicPower OpenStack Study **** def _rbd_has_extents(self, rbd_volume): """Check whether the given rbd volume has extents. Return True if has extents, otherwise False. """ extents = [] def iter_cb(offset, length, exists): if exists: extents.append(length) rbd_volume.diff_iterate(0, rbd_volume.size(), None, iter_cb) if extents: LOG.debug(_("RBD has %s extents") % (sum(extents))) return True return False
**** CubicPower OpenStack Study **** def iter_cb(offset, length, exists): if exists: extents.append(length) rbd_volume.diff_iterate(0, rbd_volume.size(), None, iter_cb) if extents: LOG.debug(_("RBD has %s extents") % (sum(extents))) return True return False
**** CubicPower OpenStack Study **** def _diff_restore_allowed(self, base_name, backup, volume, volume_file, rados_client): """Determine whether a differential restore is possible/allowed. In order for a differential restore to be performed we need: * destination volume must be RBD * destination volume must have zero extents * backup base image must exist * backup must have a restore point Returns True if differential restore is allowed, False otherwise. """ not_allowed = (False, None) if self._file_is_rbd(volume_file): # NOTE(dosaboy): base_name here must be diff format. rbd_exists, base_name = self._rbd_image_exists(base_name, backup['volume_id'], rados_client) if not rbd_exists: return not_allowed # Get the restore point. If no restore point is found, we assume # that the backup was not performed using diff/incremental methods # so we enforce full copy. restore_point = self._get_restore_point(base_name, backup['id']) # If the volume we are restoring to is the volume the backup was # made from, force a full restore since a diff will not work in # this case. if volume['id'] == backup['volume_id']: msg = _("Destination volume is same as backup source volume - " "forcing full copy") LOG.debug(msg) return False, restore_point if restore_point: # If the destination volume has extents we cannot allow a diff # restore. if self._rbd_has_extents(volume_file.rbd_image): # We return the restore point so that a full copy is done # from snapshot. LOG.debug(_("Destination has extents - forcing full copy")) return False, restore_point return True, restore_point else: LOG.info(_("No restore point found for backup='%s', forcing " "full copy") % (backup['id'])) return not_allowed
**** CubicPower OpenStack Study **** def _restore_volume(self, backup, volume, volume_file): """Restore volume from backup using diff transfer if possible. Attempts a differential restore and reverts to full copy if diff fails. """ volume_name = volume['name'] backup_id = backup['id'] backup_volume_id = backup['volume_id'] length = int(volume['size']) * units.GiB base_name = self._get_backup_base_name(backup['volume_id'], diff_format=True) with rbd_driver.RADOSClient(self, self._ceph_backup_pool) as client: diff_allowed, restore_point = \ self._diff_restore_allowed(base_name, backup, volume, volume_file, client) do_full_restore = True if diff_allowed: # Attempt diff try: self._diff_restore_rbd(base_name, volume_file, volume_name, restore_point, length) do_full_restore = False except exception.BackupRBDOperationFailed: LOG.debug(_("Forcing full restore")) if do_full_restore: # Otherwise full copy self._full_restore(backup_id, backup_volume_id, volume_file, volume_name, length, src_snap=restore_point)
**** CubicPower OpenStack Study **** def _restore_metadata(self, backup, volume_id): """Restore volume metadata from backup. If this backup has associated metadata, save it to the restore target otherwise do nothing. """ try: with rbd_driver.RADOSClient(self) as client: meta_bak = VolumeMetadataBackup(client, backup['id']) meta = meta_bak.get() if meta is not None: self.put_metadata(volume_id, meta) else: LOG.debug(_("Volume has no backed up metadata")) except exception.BackupMetadataUnsupportedVersion: msg = _("Metadata restore failed due to incompatible version") LOG.error(msg) raise exception.BackupOperationError(msg)
**** CubicPower OpenStack Study **** def restore(self, backup, volume_id, volume_file): """Restore volume from backup in Ceph object store. If volume metadata is available this will also be restored. """ target_volume = self.db.volume_get(self.context, volume_id) LOG.debug(_('Starting restore from Ceph backup=%(src)s to ' 'volume=%(dest)s') % {'src': backup['id'], 'dest': target_volume['name']}) try: self._restore_volume(backup, target_volume, volume_file) # Be tolerant of IO implementations that do not support fileno() try: fileno = volume_file.fileno() except IOError: LOG.debug(_("Volume_file does not support fileno() so " "skipping fsync()")) else: os.fsync(fileno) self._restore_metadata(backup, volume_id) LOG.debug(_('Restore finished successfully.')) except exception.BackupOperationError as e: LOG.error(_('Restore finished with error - %s') % (e)) raise
**** CubicPower OpenStack Study **** def delete(self, backup): """Delete the given backup from Ceph object store.""" backup_id = backup['id'] LOG.debug(_('Delete started for backup=%s') % backup['id']) delete_failed = False try: self._try_delete_base_image(backup['id'], backup['volume_id']) except self.rbd.ImageNotFound: msg = _("RBD image not found but continuing anyway so that we can " "attempt to delete metadata backup and db entry can be " "removed") LOG.warning(msg) delete_failed = True with rbd_driver.RADOSClient(self) as client: VolumeMetadataBackup(client, backup['id']).remove_if_exists() if delete_failed: LOG.info(_("Delete '%s' finished with warning") % (backup_id)) else: LOG.debug(_("Delete '%s' finished") % (backup_id)) def get_backup_driver(context): return CephBackupDriver(context)
**** CubicPower OpenStack Study **** def get_backup_driver(context): return CephBackupDriver(context)
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