glance_store/glance_store/_drivers/filesystem.py

777 lines
29 KiB
Python

# Copyright 2010 OpenStack Foundation
# Copyright 2014 Red Hat, Inc.
# 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 stat
import jsonschema
from oslo_config import cfg
from oslo_serialization import jsonutils
from oslo_utils import encodeutils
from oslo_utils import excutils
from oslo_utils import units
from six.moves import urllib
import glance_store
from glance_store import capabilities
from glance_store.common import utils
import glance_store.driver
from glance_store import exceptions
from glance_store.i18n import _, _LE, _LW
import glance_store.location
LOG = logging.getLogger(__name__)
_FILESYSTEM_CONFIGS = [
cfg.StrOpt('filesystem_store_datadir',
default='/var/lib/glance/images',
help="""
Directory to which the filesystem backend store writes images.
Upon start up, Glance creates the directory if it doesn't already
exist and verifies write access to the user under which
``glance-api`` runs. If the write access isn't available, a
``BadStoreConfiguration`` exception is raised and the filesystem
store may not be available for adding new images.
NOTE: This directory is used only when filesystem store is used as a
storage backend. Either ``filesystem_store_datadir`` or
``filesystem_store_datadirs`` option must be specified in
``glance-api.conf``. If both options are specified, a
``BadStoreConfiguration`` will be raised and the filesystem store
may not be available for adding new images.
Possible values:
* A valid path to a directory
Related options:
* ``filesystem_store_datadirs``
* ``filesystem_store_file_perm``
"""),
cfg.MultiStrOpt('filesystem_store_datadirs',
help="""
List of directories and their priorities to which the filesystem
backend store writes images.
The filesystem store can be configured to store images in multiple
directories as opposed to using a single directory specified by the
``filesystem_store_datadir`` configuration option. When using
multiple directories, each directory can be given an optional
priority to specify the preference order in which they should
be used. Priority is an integer that is concatenated to the
directory path with a colon where a higher value indicates higher
priority. When two directories have the same priority, the directory
with most free space is used. When no priority is specified, it
defaults to zero.
More information on configuring filesystem store with multiple store
directories can be found at
https://docs.openstack.org/glance/latest/configuration/configuring.html
NOTE: This directory is used only when filesystem store is used as a
storage backend. Either ``filesystem_store_datadir`` or
``filesystem_store_datadirs`` option must be specified in
``glance-api.conf``. If both options are specified, a
``BadStoreConfiguration`` will be raised and the filesystem store
may not be available for adding new images.
Possible values:
* List of strings of the following form:
* ``<a valid directory path>:<optional integer priority>``
Related options:
* ``filesystem_store_datadir``
* ``filesystem_store_file_perm``
"""),
cfg.StrOpt('filesystem_store_metadata_file',
help="""
Filesystem store metadata file.
The path to a file which contains the metadata to be returned with
any location associated with the filesystem store. The file must
contain a valid JSON object. The object should contain the keys
``id`` and ``mountpoint``. The value for both keys should be a
string.
Possible values:
* A valid path to the store metadata file
Related options:
* None
"""),
cfg.IntOpt('filesystem_store_file_perm',
default=0,
help="""
File access permissions for the image files.
Set the intended file access permissions for image data. This provides
a way to enable other services, e.g. Nova, to consume images directly
from the filesystem store. The users running the services that are
intended to be given access to could be made a member of the group
that owns the files created. Assigning a value less then or equal to
zero for this configuration option signifies that no changes be made
to the default permissions. This value will be decoded as an octal
digit.
For more information, please refer the documentation at
https://docs.openstack.org/glance/latest/configuration/configuring.html
Possible values:
* A valid file access permission
* Zero
* Any negative integer
Related options:
* None
"""),
cfg.IntOpt('filesystem_store_chunk_size',
default=64 * units.Ki,
min=1,
help="""
Chunk size, in bytes.
The chunk size used when reading or writing image files. Raising this value
may improve the throughput but it may also slightly increase the memory usage
when handling a large number of requests.
Possible Values:
* Any positive integer value
Related options:
* None
""")]
MULTI_FILESYSTEM_METADATA_SCHEMA = {
"type": "array",
"items": {
"type": "object",
"properties": {
"id": {"type": "string"},
"mountpoint": {"type": "string"}
},
"required": ["id", "mountpoint"],
}
}
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 = urllib.parse.urlparse(uri)
self.validate_schemas(uri, valid_schemas=('file://', 'filesystem://'))
self.scheme = pieces.scheme
path = (pieces.netloc + pieces.path).strip()
if path == '':
reason = _("No path specified in URI")
LOG.info(reason)
raise exceptions.BadStoreUri(message=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
"""
def __init__(self, filepath, offset=0, chunk_size=4096,
partial_length=None):
self.filepath = filepath
self.chunk_size = chunk_size
self.partial_length = partial_length
self.partial = self.partial_length is not None
self.fp = open(self.filepath, 'rb')
if offset:
self.fp.seek(offset)
def __iter__(self):
"""Return an iterator over the image file."""
try:
if self.fp:
while True:
if self.partial:
size = min(self.chunk_size, self.partial_length)
else:
size = self.chunk_size
chunk = self.fp.read(size)
if chunk:
yield chunk
if self.partial:
self.partial_length -= len(chunk)
if self.partial_length <= 0:
break
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.driver.Store):
_CAPABILITIES = (capabilities.BitMasks.READ_RANDOM |
capabilities.BitMasks.WRITE_ACCESS |
capabilities.BitMasks.DRIVER_REUSABLE)
OPTIONS = _FILESYSTEM_CONFIGS
FILESYSTEM_STORE_METADATA = None
def get_schemes(self):
return ('file', 'filesystem')
def _check_write_permission(self, datadir):
"""
Checks if directory created to write image files has
write permission.
:datadir is a directory path in which glance wites image files.
:raises: BadStoreConfiguration exception if datadir is read-only.
"""
if not os.access(datadir, os.W_OK):
msg = (_("Permission to write in %s denied") % datadir)
LOG.exception(msg)
raise exceptions.BadStoreConfiguration(
store_name="filesystem", reason=msg)
def _set_exec_permission(self, datadir):
"""
Set the execution permission of owner-group and/or other-users to
image directory if the image file which contained needs relevant
access permissions.
:datadir is a directory path in which glance writes image files.
"""
if self.backend_group:
fstore_perm = getattr(
self.conf, self.backend_group).filesystem_store_file_perm
else:
fstore_perm = self.conf.glance_store.filesystem_store_file_perm
if fstore_perm <= 0:
return
try:
mode = os.stat(datadir)[stat.ST_MODE]
perm = int(str(fstore_perm), 8)
if perm & stat.S_IRWXO > 0:
if not mode & stat.S_IXOTH:
# chmod o+x
mode |= stat.S_IXOTH
os.chmod(datadir, mode)
if perm & stat.S_IRWXG > 0:
if not mode & stat.S_IXGRP:
# chmod g+x
os.chmod(datadir, mode | stat.S_IXGRP)
except (IOError, OSError):
LOG.warning(_LW("Unable to set execution permission of "
"owner-group and/or other-users to datadir: %s")
% datadir)
def _create_image_directories(self, directory_paths):
"""
Create directories to write image files if
it does not exist.
:directory_paths is a list of directories belonging to glance store.
:raises: BadStoreConfiguration exception if creating a directory fails.
"""
for datadir in directory_paths:
if os.path.exists(datadir):
self._check_write_permission(datadir)
self._set_exec_permission(datadir)
else:
msg = _("Directory to write image files does not exist "
"(%s). Creating.") % datadir
LOG.info(msg)
try:
os.makedirs(datadir)
self._check_write_permission(datadir)
self._set_exec_permission(datadir)
except (IOError, OSError):
if os.path.exists(datadir):
# NOTE(markwash): If the path now exists, some other
# process must have beat us in the race condition.
# But it doesn't hurt, so we can safely ignore
# the error.
self._check_write_permission(datadir)
self._set_exec_permission(datadir)
continue
reason = _("Unable to create datadir: %s") % datadir
LOG.error(reason)
raise exceptions.BadStoreConfiguration(
store_name="filesystem", reason=reason)
def _validate_metadata(self, metadata_file):
"""Validate metadata against json schema.
If metadata is valid then cache metadata and use it when
creating new image.
:param metadata_file: JSON metadata file path
:raises: BadStoreConfiguration exception if metadata is not valid.
"""
try:
with open(metadata_file, 'rb') as fptr:
metadata = jsonutils.load(fptr)
if isinstance(metadata, dict):
# If metadata is of type dictionary
# i.e. - it contains only one mountpoint
# then convert it to list of dictionary.
metadata = [metadata]
# Validate metadata against json schema
jsonschema.validate(metadata, MULTI_FILESYSTEM_METADATA_SCHEMA)
glance_store.check_location_metadata(metadata)
self.FILESYSTEM_STORE_METADATA = metadata
except (jsonschema.exceptions.ValidationError,
exceptions.BackendException, ValueError) as vee:
err_msg = encodeutils.exception_to_unicode(vee)
reason = _('The JSON in the metadata file %(file)s is '
'not valid and it can not be used: '
'%(vee)s.') % dict(file=metadata_file,
vee=err_msg)
LOG.error(reason)
raise exceptions.BadStoreConfiguration(
store_name="filesystem", reason=reason)
except IOError as ioe:
err_msg = encodeutils.exception_to_unicode(ioe)
reason = _('The path for the metadata file %(file)s could '
'not be accessed: '
'%(ioe)s.') % dict(file=metadata_file,
ioe=err_msg)
LOG.error(reason)
raise exceptions.BadStoreConfiguration(
store_name="filesystem", reason=reason)
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 `exceptions.BadStoreConfiguration`
"""
if self.backend_group:
store_conf = getattr(self.conf, self.backend_group)
else:
store_conf = self.conf.glance_store
fdir = store_conf.filesystem_store_datadir
fdirs = store_conf.filesystem_store_datadirs
fstore_perm = store_conf.filesystem_store_file_perm
meta_file = store_conf.filesystem_store_metadata_file
self.chunk_size = store_conf.filesystem_store_chunk_size
self.READ_CHUNKSIZE = self.chunk_size
self.WRITE_CHUNKSIZE = self.READ_CHUNKSIZE
if not (fdir or fdirs):
reason = (_("Specify at least 'filesystem_store_datadir' or "
"'filesystem_store_datadirs' option"))
LOG.error(reason)
raise exceptions.BadStoreConfiguration(store_name="filesystem",
reason=reason)
if fdir and fdirs:
reason = (_("Specify either 'filesystem_store_datadir' or "
"'filesystem_store_datadirs' option"))
LOG.error(reason)
raise exceptions.BadStoreConfiguration(store_name="filesystem",
reason=reason)
if fstore_perm > 0:
perm = int(str(fstore_perm), 8)
if not perm & stat.S_IRUSR:
reason = _LE("Specified an invalid "
"'filesystem_store_file_perm' option which "
"could make image file to be unaccessible by "
"glance service.")
LOG.error(reason)
reason = _("Invalid 'filesystem_store_file_perm' option.")
raise exceptions.BadStoreConfiguration(store_name="filesystem",
reason=reason)
self.multiple_datadirs = False
directory_paths = set()
if fdir:
self.datadir = fdir
directory_paths.add(self.datadir)
else:
self.multiple_datadirs = True
self.priority_data_map = {}
for datadir in fdirs:
(datadir_path,
priority) = self._get_datadir_path_and_priority(datadir)
priority_paths = self.priority_data_map.setdefault(
int(priority), [])
self._check_directory_paths(datadir_path, directory_paths,
priority_paths)
directory_paths.add(datadir_path)
priority_paths.append(datadir_path)
self.priority_list = sorted(self.priority_data_map,
reverse=True)
self._create_image_directories(directory_paths)
if meta_file:
self._validate_metadata(meta_file)
def _check_directory_paths(self, datadir_path, directory_paths,
priority_paths):
"""
Checks if directory_path is already present in directory_paths.
:datadir_path is directory path.
:datadir_paths is set of all directory paths.
:raises: BadStoreConfiguration exception if same directory path is
already present in directory_paths.
"""
if datadir_path in directory_paths:
msg = (_("Directory %(datadir_path)s specified "
"multiple times in filesystem_store_datadirs "
"option of filesystem configuration") %
{'datadir_path': datadir_path})
# If present with different priority it's a bad configuration
if datadir_path not in priority_paths:
LOG.exception(msg)
raise exceptions.BadStoreConfiguration(
store_name="filesystem", reason=msg)
# Present with same prio (exact duplicate) only deserves a warning
LOG.warning(msg)
def _get_datadir_path_and_priority(self, datadir):
"""
Gets directory paths and its priority from
filesystem_store_datadirs option in glance-api.conf.
:param datadir: is directory path with its priority.
:returns: datadir_path as directory path
priority as priority associated with datadir_path
:raises: BadStoreConfiguration exception if priority is invalid or
empty directory path is specified.
"""
priority = 0
parts = [part.strip() for part in datadir.rsplit(":", 1)]
datadir_path = parts[0]
if len(parts) == 2 and parts[1]:
priority = parts[1]
if not priority.isdigit():
msg = (_("Invalid priority value %(priority)s in "
"filesystem configuration") % {'priority': priority})
LOG.exception(msg)
raise exceptions.BadStoreConfiguration(
store_name="filesystem", reason=msg)
if not datadir_path:
msg = _("Invalid directory specified in filesystem configuration")
LOG.exception(msg)
raise exceptions.BadStoreConfiguration(
store_name="filesystem", reason=msg)
return datadir_path, priority
@staticmethod
def _resolve_location(location):
filepath = location.store_location.path
if not os.path.exists(filepath):
raise exceptions.NotFound(image=filepath)
filesize = os.path.getsize(filepath)
return filepath, filesize
def _get_metadata(self, filepath):
"""Return metadata dictionary.
If metadata is provided as list of dictionaries then return
metadata as dictionary containing 'id' and 'mountpoint'.
If there are multiple nfs directories (mountpoints) configured
for glance, then we need to create metadata JSON file as list
of dictionaries containing all mountpoints with unique id.
But Nova will not be able to find in which directory (mountpoint)
image is present if we store list of dictionary(containing mountpoints)
in glance image metadata. So if there are multiple mountpoints then
we will return dict containing exact mountpoint where image is stored.
If image path does not start with any of the 'mountpoint' provided
in metadata JSON file then error is logged and empty
dictionary is returned.
:param filepath: Path of image on store
:returns: metadata dictionary
"""
if self.FILESYSTEM_STORE_METADATA:
for image_meta in self.FILESYSTEM_STORE_METADATA:
if filepath.startswith(image_meta['mountpoint']):
return image_meta
reason = (_LE("The image path %(path)s does not match with "
"any of the mountpoint defined in "
"metadata: %(metadata)s. An empty dictionary "
"will be returned to the client.")
% dict(path=filepath,
metadata=self.FILESYSTEM_STORE_METADATA))
LOG.error(reason)
return {}
@capabilities.check
def get(self, location, offset=0, chunk_size=None, context=None):
"""
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_store.exceptions.NotFound` if image does not exist
"""
filepath, filesize = self._resolve_location(location)
msg = _("Found image at %s. Returning in ChunkedFile.") % filepath
LOG.debug(msg)
return (ChunkedFile(filepath,
offset=offset,
chunk_size=self.READ_CHUNKSIZE,
partial_length=chunk_size),
chunk_size or filesize)
def get_size(self, location, context=None):
"""
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_store.exceptions.NotFound` if image does not exist
:rtype: int
"""
filepath, filesize = self._resolve_location(location)
msg = _("Found image at %s.") % filepath
LOG.debug(msg)
return filesize
@capabilities.check
def delete(self, location, context=None):
"""
Takes a `glance_store.location.Location` object that indicates
where to find the image file to delete
:param location: `glance_store.location.Location` object, supplied
from glance_store.location.get_location_from_uri()
:raises: NotFound if image does not exist
:raises: Forbidden if cannot delete because of permissions
"""
loc = location.store_location
fn = loc.path
if os.path.exists(fn):
try:
LOG.debug(_("Deleting image at %(fn)s"), {'fn': fn})
os.unlink(fn)
except OSError:
raise exceptions.Forbidden(
message=(_("You cannot delete file %s") % fn))
else:
raise exceptions.NotFound(image=fn)
def _get_capacity_info(self, mount_point):
"""Calculates total available space for given mount point.
:mount_point is path of glance data directory
"""
# Calculate total available space
stvfs_result = os.statvfs(mount_point)
total_available_space = stvfs_result.f_bavail * stvfs_result.f_bsize
return max(0, total_available_space)
def _find_best_datadir(self, image_size):
"""Finds the best datadir by priority and free space.
Traverse directories returning the first one that has sufficient
free space, in priority order. If two suitable directories have
the same priority, choose the one with the most free space
available.
:param image_size: size of image being uploaded.
:returns: best_datadir as directory path of the best priority datadir.
:raises: exceptions.StorageFull if there is no datadir in
self.priority_data_map that can accommodate the image.
"""
if not self.multiple_datadirs:
return self.datadir
best_datadir = None
max_free_space = 0
for priority in self.priority_list:
for datadir in self.priority_data_map.get(priority):
free_space = self._get_capacity_info(datadir)
if free_space >= image_size and free_space > max_free_space:
max_free_space = free_space
best_datadir = datadir
# If datadir is found which can accommodate image and has maximum
# free space for the given priority then break the loop,
# else continue to lookup further.
if best_datadir:
break
else:
msg = (_("There is no enough disk space left on the image "
"storage media. requested=%s") % image_size)
LOG.exception(msg)
raise exceptions.StorageFull(message=msg)
return best_datadir
@glance_store.driver.back_compat_add
@capabilities.check
def add(self, image_id, image_file, image_size, hashing_algo, context=None,
verifier=None):
"""
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
:param hashing_algo: A hashlib algorithm identifier (string)
:param context: The request context
:param verifier: An object used to verify signatures for images
:returns: tuple of: (1) URL in backing store, (2) bytes written,
(3) checksum, (4) multihash value, and (5) a dictionary
with storage system specific information
:raises: `glance_store.exceptions.Duplicate` if the image already
exists
: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.
"""
datadir = self._find_best_datadir(image_size)
filepath = os.path.join(datadir, str(image_id))
if os.path.exists(filepath):
raise exceptions.Duplicate(image=filepath)
os_hash_value = hashlib.new(str(hashing_algo))
checksum = hashlib.md5()
bytes_written = 0
try:
with open(filepath, 'wb') as f:
for buf in utils.chunkreadable(image_file,
self.WRITE_CHUNKSIZE):
bytes_written += len(buf)
os_hash_value.update(buf)
checksum.update(buf)
if verifier:
verifier.update(buf)
f.write(buf)
except IOError as e:
if e.errno != errno.EACCES:
self._delete_partial(filepath, image_id)
errors = {errno.EFBIG: exceptions.StorageFull(),
errno.ENOSPC: exceptions.StorageFull(),
errno.EACCES: exceptions.StorageWriteDenied()}
raise errors.get(e.errno, e)
except Exception:
with excutils.save_and_reraise_exception():
self._delete_partial(filepath, image_id)
hash_hex = os_hash_value.hexdigest()
checksum_hex = checksum.hexdigest()
metadata = self._get_metadata(filepath)
LOG.debug(("Wrote %(bytes_written)d bytes to %(filepath)s with "
"checksum %(checksum_hex)s and multihash %(hash_hex)s"),
{'bytes_written': bytes_written,
'filepath': filepath,
'checksum_hex': checksum_hex,
'hash_hex': hash_hex})
if self.backend_group:
fstore_perm = getattr(
self.conf, self.backend_group).filesystem_store_file_perm
else:
fstore_perm = self.conf.glance_store.filesystem_store_file_perm
if fstore_perm > 0:
perm = int(str(fstore_perm), 8)
try:
os.chmod(filepath, perm)
except (IOError, OSError):
LOG.warning(_LW("Unable to set permission to image: %s") %
filepath)
# Add store backend information to location metadata
if self.backend_group:
metadata['backend'] = u"%s" % self.backend_group
return ('file://%s' % filepath,
bytes_written,
checksum_hex,
hash_hex,
metadata)
@staticmethod
def _delete_partial(filepath, iid):
try:
os.unlink(filepath)
except Exception as e:
msg = _('Unable to remove partial image '
'data for image %(iid)s: %(e)s')
LOG.error(msg % dict(iid=iid,
e=encodeutils.exception_to_unicode(e)))