deb-glance/glance/store/filesystem.py
Eoghan Glynn c83bce1ce6 Support new image copied from external storage.
Implements bp retrieve-image-from

Added support for a new header:

  x-glance-api-copy-from: URI

where URI is a HTTP, S3, or Swift location that's accessible to the
glance API service. Where present, the image content is copied from
the external store to the backend store currently configured for
the glance API service.

Impedence between the representation returned by Store.get() and
the implicit requirements of Store.add() required careful iterator/
filelike wrapping.

Also rationalized the S3 and Swift functional test setup logic and
added a new decorator-based mechanism to allow a functional testcase
require multiple backend stores to be available and configured.

Change-Id: If783a09c273832b8926aabc60b7eba8b3ab956d6
2012-02-22 18:03:48 +00:00

223 lines
7.6 KiB
Python

# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2010 OpenStack, LLC
# 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.
"""
A simple filesystem-backed store
"""
import errno
import hashlib
import logging
import os
import urlparse
from glance.common import cfg
from glance.common import exception
from glance.common import utils
import glance.store
import glance.store.base
import glance.store.location
logger = logging.getLogger('glance.store.filesystem')
class StoreLocation(glance.store.location.StoreLocation):
"""Class describing a Filesystem URI"""
def process_specs(self):
self.scheme = self.specs.get('scheme', 'file')
self.path = self.specs.get('path')
def get_uri(self):
return "file://%s" % self.path
def parse_uri(self, uri):
"""
Parse URLs. This method fixes an issue where credentials specified
in the URL are interpreted differently in Python 2.6.1+ than prior
versions of Python.
"""
pieces = urlparse.urlparse(uri)
assert pieces.scheme in ('file', 'filesystem')
self.scheme = pieces.scheme
path = (pieces.netloc + pieces.path).strip()
if path == '':
reason = _("No path specified")
raise exception.BadStoreUri(uri, reason)
self.path = path
class ChunkedFile(object):
"""
We send this back to the Glance API server as
something that can iterate over a large file
"""
CHUNKSIZE = 65536
def __init__(self, filepath):
self.filepath = filepath
self.fp = open(self.filepath, 'rb')
def __iter__(self):
"""Return an iterator over the image file"""
try:
while True:
chunk = self.fp.read(ChunkedFile.CHUNKSIZE)
if chunk:
yield chunk
else:
break
finally:
self.close()
def close(self):
"""Close the internal file pointer"""
if self.fp:
self.fp.close()
self.fp = None
class Store(glance.store.base.Store):
datadir_opt = cfg.StrOpt('filesystem_store_datadir')
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`
"""
self.conf.register_opt(self.datadir_opt)
self.datadir = self.conf.filesystem_store_datadir
if self.datadir is None:
reason = _("Could not find %s in configuration options.") % \
'filesystem_store_datadir'
logger.error(reason)
raise exception.BadStoreConfiguration(store_name="filesystem",
reason=reason)
if not os.path.exists(self.datadir):
msg = _("Directory to write image files does not exist "
"(%s). Creating.") % self.datadir
logger.info(msg)
try:
os.makedirs(self.datadir)
except IOError:
reason = _("Unable to create datadir: %s") % self.datadir
logger.error(reason)
raise exception.BadStoreConfiguration(store_name="filesystem",
reason=reason)
def get(self, location):
"""
Takes a `glance.store.location.Location` object that indicates
where to find the image file, and returns a tuple of generator
(for reading the image file) and 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
"""
loc = location.store_location
filepath = loc.path
if not os.path.exists(filepath):
raise exception.NotFound(_("Image file %s not found") % filepath)
else:
msg = _("Found image at %s. Returning in ChunkedFile.") % filepath
logger.debug(msg)
return (ChunkedFile(filepath), None)
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
:raises NotAuthorized if cannot delete because of permissions
"""
loc = location.store_location
fn = loc.path
if os.path.exists(fn):
try:
logger.debug(_("Deleting image at %(fn)s") % locals())
os.unlink(fn)
except OSError:
raise exception.NotAuthorized(_("You cannot delete file %s")
% fn)
else:
raise exception.NotFound(_("Image file %s does not exist") % fn)
def add(self, image_id, image_file, image_size):
"""
Stores an image file with supplied identifier to the backend
storage system and returns an `glance.store.ImageAddResult` object
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 `glance.store.ImageAddResult` object
:raises `glance.common.exception.Duplicate` if the image already
existed
:note By default, the backend writes the image data to a file
`/<DATADIR>/<ID>`, where <DATADIR> is the value of
the filesystem_store_datadir configuration option and <ID>
is the supplied image ID.
"""
filepath = os.path.join(self.datadir, str(image_id))
if os.path.exists(filepath):
raise exception.Duplicate(_("Image file %s already exists!")
% filepath)
checksum = hashlib.md5()
bytes_written = 0
try:
with open(filepath, 'wb') as f:
for buf in utils.chunkreadable(image_file,
ChunkedFile.CHUNKSIZE):
bytes_written += len(buf)
checksum.update(buf)
f.write(buf)
except IOError as e:
if e.errno in [errno.EFBIG, errno.ENOSPC]:
raise exception.StorageFull()
elif e.errno == errno.EACCES:
raise exception.StorageWriteDenied()
else:
raise
checksum_hex = checksum.hexdigest()
logger.debug(_("Wrote %(bytes_written)d bytes to %(filepath)s with "
"checksum %(checksum_hex)s") % locals())
return ('file://%s' % filepath, bytes_written, checksum_hex)
glance.store.register_store(__name__, ['filesystem', 'file'])