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OpenStack Study: sheepdog.py**** CubicPower OpenStack Study ****
# 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. """Storage backend for Sheepdog storage system""" import hashlib from oslo.config import cfg from glance.common import exception from glance.common import utils from glance.openstack.common import excutils import glance.openstack.common.log as logging from glance.openstack.common import processutils from glance.openstack.common import units import glance.store import glance.store.base import glance.store.location LOG = logging.getLogger(__name__) DEFAULT_ADDR = '127.0.0.1' DEFAULT_PORT = 7000 DEFAULT_CHUNKSIZE = 64 # in MiB LOG = logging.getLogger(__name__) sheepdog_opts = [ cfg.IntOpt('sheepdog_store_chunk_size', default=DEFAULT_CHUNKSIZE, help=_('Images will be chunked into objects of this size ' '(in megabytes). For best performance, this should be ' 'a power of two.')), cfg.IntOpt('sheepdog_store_port', default=DEFAULT_PORT, help=_('Port of sheep daemon.')), cfg.StrOpt('sheepdog_store_address', default=DEFAULT_ADDR, help=_('IP address of sheep daemon.')) ] CONF = cfg.CONF CONF.register_opts(sheepdog_opts)
**** CubicPower OpenStack Study **** class SheepdogImage: """Class describing an image stored in Sheepdog storage."""
**** CubicPower OpenStack Study **** def __init__(self, addr, port, name, chunk_size): self.addr = addr self.port = port self.name = name self.chunk_size = chunk_size
**** CubicPower OpenStack Study **** def _run_command(self, command, data, *params): cmd = ["collie", "vdi"] cmd.extend(command) cmd.extend(["-a", self.addr, "-p", self.port, self.name]) cmd.extend(params) try: return processutils.execute(*cmd, process_input=data)[0] except (processutils.ProcessExecutionError, OSError) as exc: LOG.error(exc) raise glance.store.BackendException(exc)
**** CubicPower OpenStack Study **** def get_size(self): """ Return the size of the this iamge Sheepdog Usage: collie vdi list -r -a address -p port image """ out = self._run_command(["list", "-r"], None) return long(out.split(' ')[3])
**** CubicPower OpenStack Study **** def read(self, offset, count): """ Read up to 'count' bytes from this image starting at 'offset' and return the data. Sheepdog Usage: collie vdi read -a address -p port image offset len """ return self._run_command(["read"], None, str(offset), str(count))
**** CubicPower OpenStack Study **** def write(self, data, offset, count): """ Write up to 'count' bytes from the data to this image starting at 'offset' Sheepdog Usage: collie vdi write -a address -p port image offset len """ self._run_command(["write"], data, str(offset), str(count))
**** CubicPower OpenStack Study **** def create(self, size): """ Create this image in the Sheepdog cluster with size 'size'. Sheepdog Usage: collie vdi create -a address -p port image size """ self._run_command(["create"], None, str(size))
**** CubicPower OpenStack Study **** def delete(self): """ Delete this image in the Sheepdog cluster Sheepdog Usage: collie vdi delete -a address -p port image """ self._run_command(["delete"], None)
**** CubicPower OpenStack Study **** def exist(self): """ Check if this image exists in the Sheepdog cluster via 'list' command Sheepdog Usage: collie vdi list -r -a address -p port image """ out = self._run_command(["list", "-r"], None) if not out: return False else: return True
**** CubicPower OpenStack Study **** class StoreLocation(glance.store.location.StoreLocation): """ Class describing a Sheepdog URI. This is of the form: sheepdog://image-id """
**** CubicPower OpenStack Study **** def process_specs(self): self.image = self.specs.get('image')
**** CubicPower OpenStack Study **** def get_uri(self): return "sheepdog://%s" % self.image
**** CubicPower OpenStack Study **** def parse_uri(self, uri): valid_schema = 'sheepdog://' if not uri.startswith(valid_schema): raise exception.BadStoreUri(_("URI must start with %s://") % valid_schema) self.image = uri[len(valid_schema):] if not utils.is_uuid_like(self.image): raise exception.BadStoreUri(_("URI must contains well-formated " "image id"))
**** CubicPower OpenStack Study **** class ImageIterator(object): """ Reads data from an Sheepdog image, one chunk at a time. """
**** CubicPower OpenStack Study **** def __init__(self, image): self.image = image
**** CubicPower OpenStack Study **** def __iter__(self): image = self.image total = left = image.get_size() while left > 0: length = min(image.chunk_size, left) data = image.read(total - left, length) left -= len(data) yield data raise StopIteration()
**** CubicPower OpenStack Study **** class Store(glance.store.base.Store): """Sheepdog backend adapter.""" EXAMPLE_URL = "sheepdog://image"
**** CubicPower OpenStack Study **** def get_schemes(self): return ('sheepdog',)
**** CubicPower OpenStack Study **** def configure_add(self): """ Configure the Store to use the stored configuration options Any store that needs special configuration should implement this method. If the store was not able to successfully configure itself, it should raise `exception.BadStoreConfiguration` """ try: self.chunk_size = CONF.sheepdog_store_chunk_size * units.Mi self.addr = CONF.sheepdog_store_address.strip() self.port = CONF.sheepdog_store_port except cfg.ConfigFileValueError as e: reason = _("Error in store configuration: %s") % e LOG.error(reason) raise exception.BadStoreConfiguration(store_name='sheepdog', reason=reason) if ' ' in self.addr: reason = (_("Invalid address configuration of sheepdog store: %s") % self.addr) LOG.error(reason) raise exception.BadStoreConfiguration(store_name='sheepdog', reason=reason) try: cmd = ["collie", "vdi", "list", "-a", self.addr, "-p", self.port] processutils.execute(*cmd) except Exception as e: reason = _("Error in store configuration: %s") % e LOG.error(reason) raise exception.BadStoreConfiguration(store_name='sheepdog', reason=reason)
**** CubicPower OpenStack Study **** def get(self, location): """ Takes a `glance.store.location.Location` object that indicates where to find the image file, and returns a generator for reading the image file :param location `glance.store.location.Location` object, supplied from glance.store.location.get_location_from_uri() :raises `glance.exception.NotFound` if image does not exist """ loc = location.store_location image = SheepdogImage(self.addr, self.port, loc.image, self.chunk_size) if not image.exist(): raise exception.NotFound(_("Sheepdog image %s does not exist") % image.name) return (ImageIterator(image), image.get_size())
**** CubicPower OpenStack Study **** def get_size(self, location): """ Takes a `glance.store.location.Location` object that indicates where to find the image file and returns the image size :param location `glance.store.location.Location` object, supplied from glance.store.location.get_location_from_uri() :raises `glance.exception.NotFound` if image does not exist :rtype int """ loc = location.store_location image = SheepdogImage(self.addr, self.port, loc.image, self.chunk_size) if not image.exist(): raise exception.NotFound(_("Sheepdog image %s does not exist") % image.name) return image.get_size()
**** CubicPower OpenStack Study **** def add(self, image_id, image_file, image_size): """ Stores an image file with supplied identifier to the backend storage system and returns a tuple containing information about the stored image. :param image_id: The opaque image identifier :param image_file: The image data to write, as a file-like object :param image_size: The size of the image data to write, in bytes :retval tuple of URL in backing store, bytes written, and checksum :raises `glance.common.exception.Duplicate` if the image already existed """ image = SheepdogImage(self.addr, self.port, image_id, self.chunk_size) if image.exist(): raise exception.Duplicate(_("Sheepdog image %s already exists") % image_id) location = StoreLocation({'image': image_id}) checksum = hashlib.md5() image.create(image_size) try: total = left = image_size while left > 0: length = min(self.chunk_size, left) data = image_file.read(length) image.write(data, total - left, length) left -= length checksum.update(data) except Exception: # Note(zhiyan): clean up already received data when # error occurs such as ImageSizeLimitExceeded exception. with excutils.save_and_reraise_exception(): image.delete() return (location.get_uri(), image_size, checksum.hexdigest(), {})
**** CubicPower OpenStack Study **** def delete(self, location): """ Takes a `glance.store.location.Location` object that indicates where to find the image file to delete :location `glance.store.location.Location` object, supplied from glance.store.location.get_location_from_uri() :raises NotFound if image does not exist """ loc = location.store_location image = SheepdogImage(self.addr, self.port, loc.image, self.chunk_size) if not image.exist(): raise exception.NotFound(_("Sheepdog image %s does not exist") % loc.image) image.delete()
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