openstack/deb-glance
Code Issues Proposed changes
cb70ff9f51
deb-glance/glance/store/swift.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

569 lines
23 KiB
Python
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2010-2011 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.
"""Storage backend for SWIFT"""
from __future__ import absolute_import
import hashlib
import httplib
import logging
import math
import tempfile
import urlparse
from glance.common import cfg
from glance.common import exception
import glance.store
import glance.store.base
import glance.store.location
try:
from swift.common import client as swift_client
except ImportError:
pass
DEFAULT_CONTAINER = 'glance'
DEFAULT_LARGE_OBJECT_SIZE = 5 * 1024 # 5GB
DEFAULT_LARGE_OBJECT_CHUNK_SIZE = 200 # 200M
ONE_MB = 1000 * 1024
logger = logging.getLogger('glance.store.swift')
class StoreLocation(glance.store.location.StoreLocation):
"""
Class describing a Swift URI. A Swift URI can look like any of
the following:
swift://user:pass@authurl.com/container/obj-id
swift://account:user:pass@authurl.com/container/obj-id
swift+http://user:pass@authurl.com/container/obj-id
swift+https://user:pass@authurl.com/container/obj-id
The swift+http:// URIs indicate there is an HTTP authentication URL.
The default for Swift is an HTTPS authentication URL, so swift:// and
swift+https:// are the same...
"""
def process_specs(self):
self.scheme = self.specs.get('scheme', 'swift+https')
self.user = self.specs.get('user')
self.key = self.specs.get('key')
self.authurl = self.specs.get('authurl')
self.container = self.specs.get('container')
self.obj = self.specs.get('obj')
def _get_credstring(self):
if self.user:
return '%s:%s@' % (self.user, self.key)
return ''
def get_uri(self):
authurl = self.authurl
if authurl.startswith('http://'):
authurl = authurl[7:]
elif authurl.startswith('https://'):
authurl = authurl[8:]
credstring = self._get_credstring()
authurl = authurl.strip('/')
container = self.container.strip('/')
obj = self.obj.strip('/')
return '%s://%s%s/%s/%s' % (self.scheme, credstring, authurl,
container, obj)
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. It also deals with the peculiarity that new-style
Swift URIs have where a username can contain a ':', like so:
swift://account:user:pass@authurl.com/container/obj
"""
# Make sure that URIs that contain multiple schemes, such as:
# swift://user:pass@http://authurl.com/v1/container/obj
# are immediately rejected.
if uri.count('://') != 1:
reason = _(
"URI cannot contain more than one occurrence of a scheme."
"If you have specified a URI like "
"swift://user:pass@http://authurl.com/v1/container/obj"
", you need to change it to use the swift+http:// scheme, "
"like so: "
"swift+http://user:pass@authurl.com/v1/container/obj"
)
raise exception.BadStoreUri(uri, reason)
pieces = urlparse.urlparse(uri)
assert pieces.scheme in ('swift', 'swift+http', 'swift+https')
self.scheme = pieces.scheme
netloc = pieces.netloc
path = pieces.path.lstrip('/')
if netloc != '':
# > Python 2.6.1
if '@' in netloc:
creds, netloc = netloc.split('@')
else:
creds = None
else:
# Python 2.6.1 compat
# see lp659445 and Python issue7904
if '@' in path:
creds, path = path.split('@')
else:
creds = None
netloc = path[0:path.find('/')].strip('/')
path = path[path.find('/'):].strip('/')
if creds:
cred_parts = creds.split(':')
# User can be account:user, in which case cred_parts[0:2] will be
# the account and user. Combine them into a single username of
# account:user
if len(cred_parts) == 1:
reason = (_("Badly formed credentials '%(creds)s' in Swift "
"URI") % locals())
raise exception.BadStoreUri(uri, reason)
elif len(cred_parts) == 3:
user = ':'.join(cred_parts[0:2])
else:
user = cred_parts[0]
key = cred_parts[-1]
self.user = user
self.key = key
else:
self.user = None
path_parts = path.split('/')
try:
self.obj = path_parts.pop()
self.container = path_parts.pop()
if not netloc.startswith('http'):
# push hostname back into the remaining to build full authurl
path_parts.insert(0, netloc)
self.authurl = '/'.join(path_parts)
except IndexError:
reason = _("Badly formed Swift URI")
raise exception.BadStoreUri(uri, reason)
@property
def swift_auth_url(self):
"""
Creates a fully-qualified auth url that the Swift client library can
use. The scheme for the auth_url is determined using the scheme
included in the `location` field.
HTTPS is assumed, unless 'swift+http' is specified.
"""
if self.scheme in ('swift+https', 'swift'):
auth_scheme = 'https://'
else:
auth_scheme = 'http://'
full_url = ''.join([auth_scheme, self.authurl])
return full_url
class Store(glance.store.base.Store):
"""An implementation of the swift backend adapter."""
EXAMPLE_URL = "swift://<USER>:<KEY>@<AUTH_ADDRESS>/<CONTAINER>/<FILE>"
CHUNKSIZE = 65536
opts = [
cfg.BoolOpt('swift_enable_snet', default=False),
cfg.StrOpt('swift_store_auth_address'),
cfg.StrOpt('swift_store_user'),
cfg.StrOpt('swift_store_key'),
cfg.StrOpt('swift_store_container',
default=DEFAULT_CONTAINER),
cfg.IntOpt('swift_store_large_object_size',
default=DEFAULT_LARGE_OBJECT_SIZE),
cfg.IntOpt('swift_store_large_object_chunk_size',
default=DEFAULT_LARGE_OBJECT_CHUNK_SIZE),
cfg.BoolOpt('swift_store_create_container_on_put', default=False),
]
def configure(self):
self.conf.register_opts(self.opts)
self.snet = self.conf.swift_enable_snet
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.auth_address = self._option_get('swift_store_auth_address')
self.user = self._option_get('swift_store_user')
self.key = self._option_get('swift_store_key')
self.container = self.conf.swift_store_container
try:
# The config file has swift_store_large_object_*size in MB, but
# internally we store it in bytes, since the image_size parameter
# passed to add() is also in bytes.
self.large_object_size = \
self.conf.swift_store_large_object_size * ONE_MB
self.large_object_chunk_size = \
self.conf.swift_store_large_object_chunk_size * ONE_MB
except cfg.ConfigFileValueError, e:
reason = _("Error in configuration conf: %s") % e
logger.error(reason)
raise exception.BadStoreConfiguration(store_name="swift",
reason=reason)
self.scheme = 'swift+https'
if self.auth_address.startswith('http://'):
self.scheme = 'swift+http'
self.full_auth_address = self.auth_address
elif self.auth_address.startswith('https://'):
self.full_auth_address = self.auth_address
else: # Defaults https
self.full_auth_address = 'https://' + self.auth_address
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
swift_conn = self._make_swift_connection(
auth_url=loc.swift_auth_url, user=loc.user, key=loc.key)
try:
(resp_headers, resp_body) = swift_conn.get_object(
container=loc.container, obj=loc.obj,
resp_chunk_size=self.CHUNKSIZE)
except swift_client.ClientException, e:
if e.http_status == httplib.NOT_FOUND:
uri = location.get_store_uri()
raise exception.NotFound(_("Swift could not find image at "
"uri %(uri)s") % locals())
else:
raise
#if expected_size:
# obj_size = int(resp_headers['content-length'])
# if obj_size != expected_size:
# raise glance.store.BackendException(
# "Expected %s byte file, Swift has %s bytes" %
# (expected_size, obj_size))
class ResponseIndexable(glance.store.Indexable):
def another(self):
try:
return self.wrapped.next()
except StopIteration:
return ''
length = resp_headers.get('content-length')
return (ResponseIndexable(resp_body, length), length)
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 (or 0
if unavailable)
:param location `glance.store.location.Location` object, supplied
from glance.store.location.get_location_from_uri()
"""
loc = location.store_location
swift_conn = self._make_swift_connection(
auth_url=loc.swift_auth_url, user=loc.user, key=loc.key)
try:
resp_headers = swift_conn.head_object(container=loc.container,
obj=loc.obj)
return resp_headers.get('content-length', 0)
except Exception:
return 0
def _make_swift_connection(self, auth_url, user, key):
"""
Creates a connection using the Swift client library.
"""
snet = self.snet
logger.debug(_("Creating Swift connection with "
"(auth_address=%(auth_url)s, user=%(user)s, "
"snet=%(snet)s)") % locals())
return swift_client.Connection(
authurl=auth_url, user=user, key=key, snet=snet)
def _option_get(self, param):
result = getattr(self.conf, param)
if not result:
reason = (_("Could not find %(param)s in configuration "
"options.") % locals())
logger.error(reason)
raise exception.BadStoreConfiguration(store_name="swift",
reason=reason)
return result
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
Swift writes the image data using the scheme:
``swift://<USER>:<KEY>@<AUTH_ADDRESS>/<CONTAINER>/<ID>`
where:
<USER> = ``swift_store_user``
<KEY> = ``swift_store_key``
<AUTH_ADDRESS> = ``swift_store_auth_address``
<CONTAINER> = ``swift_store_container``
<ID> = The id of the image being added
:note Swift auth URLs by default use HTTPS. To specify an HTTP
auth URL, you can specify http://someurl.com for the
swift_store_auth_address config option
:note Swift cannot natively/transparently handle objects >5GB
in size. So, if the image is greater than 5GB, we write
chunks of image data to Swift and then write an manifest
to Swift that contains information about the chunks.
This same chunking process is used by default for images
of an unknown size, as pushing them directly to swift would
fail if the image turns out to be greater than 5GB.
"""
swift_conn = self._make_swift_connection(
auth_url=self.full_auth_address, user=self.user, key=self.key)
create_container_if_missing(self.container, swift_conn, self.conf)
obj_name = str(image_id)
location = StoreLocation({'scheme': self.scheme,
'container': self.container,
'obj': obj_name,
'authurl': self.auth_address,
'user': self.user,
'key': self.key})
logger.debug(_("Adding image object '%(obj_name)s' "
"to Swift") % locals())
try:
if image_size > 0 and image_size < self.large_object_size:
# Image size is known, and is less than large_object_size.
# Send to Swift with regular PUT.
obj_etag = swift_conn.put_object(self.container, obj_name,
image_file,
content_length=image_size)
else:
# Write the image into Swift in chunks.
chunk_id = 1
if image_size > 0:
total_chunks = str(int(
math.ceil(float(image_size) /
float(self.large_object_chunk_size))))
else:
# image_size == 0 is when we don't know the size
# of the image. This can occur with older clients
# that don't inspect the payload size.
logger.debug(_("Cannot determine image size. Adding as a "
"segmented object to Swift."))
total_chunks = '?'
checksum = hashlib.md5()
combined_chunks_size = 0
while True:
chunk_size = self.large_object_chunk_size
if image_size == 0:
content_length = None
else:
left = image_size - combined_chunks_size
if left == 0:
break
if chunk_size > left:
chunk_size = left
content_length = chunk_size
chunk_name = "%s-%05d" % (obj_name, chunk_id)
reader = ChunkReader(image_file, checksum, chunk_size)
chunk_etag = swift_conn.put_object(
self.container, chunk_name, reader,
content_length=content_length)
bytes_read = reader.bytes_read
logger.debug(_("Wrote chunk %(chunk_id)d/"
"%(total_chunks)s of length %(bytes_read)d "
"to Swift returning MD5 of content: "
"%(chunk_etag)s")
% locals())
if bytes_read == 0:
# Delete the last chunk, because it's of zero size.
# This will happen if image_size == 0.
logger.debug(_("Deleting final zero-length chunk"))
swift_conn.delete_object(self.container, chunk_name)
break
chunk_id += 1
combined_chunks_size += bytes_read
# In the case we have been given an unknown image size,
# set the image_size to the total size of the combined chunks.
if image_size == 0:
image_size = combined_chunks_size
# Now we write the object manifest and return the
# manifest's etag...
manifest = "%s/%s" % (self.container, obj_name)
headers = {'ETag': hashlib.md5("").hexdigest(),
'X-Object-Manifest': manifest}
# The ETag returned for the manifest is actually the
# MD5 hash of the concatenated checksums of the strings
# of each chunk...so we ignore this result in favour of
# the MD5 of the entire image file contents, so that
# users can verify the image file contents accordingly
_ignored = swift_conn.put_object(self.container, obj_name,
None, headers=headers)
obj_etag = checksum.hexdigest()
# NOTE: We return the user and key here! Have to because
# location is used by the API server to return the actual
# image data. We *really* should consider NOT returning
# the location attribute from GET /images/<ID> and
# GET /images/details
return (location.get_uri(), image_size, obj_etag)
except swift_client.ClientException, e:
if e.http_status == httplib.CONFLICT:
raise exception.Duplicate(_("Swift already has an image at "
"location %s") % location.get_uri())
msg = (_("Failed to add object to Swift.\n"
"Got error from Swift: %(e)s") % locals())
logger.error(msg)
raise glance.store.BackendException(msg)
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
swift_conn = self._make_swift_connection(
auth_url=loc.swift_auth_url, user=loc.user, key=loc.key)
try:
# We request the manifest for the object. If one exists,
# that means the object was uploaded in chunks/segments,
# and we need to delete all the chunks as well as the
# manifest.
manifest = None
try:
headers = swift_conn.head_object(loc.container, loc.obj)
manifest = headers.get('x-object-manifest')
except swift_client.ClientException, e:
if e.http_status != httplib.NOT_FOUND:
raise
if manifest:
# Delete all the chunks before the object manifest itself
obj_container, obj_prefix = manifest.split('/', 1)
for segment in swift_conn.get_container(obj_container,
prefix=obj_prefix)[1]:
# TODO(jaypipes): This would be an easy area to parallelize
# since we're simply sending off parallelizable requests
# to Swift to delete stuff. It's not like we're going to
# be hogging up network or file I/O here...
swift_conn.delete_object(obj_container, segment['name'])
else:
swift_conn.delete_object(loc.container, loc.obj)
except swift_client.ClientException, e:
if e.http_status == httplib.NOT_FOUND:
uri = location.get_store_uri()
raise exception.NotFound(_("Swift could not find image at "
"uri %(uri)s") % locals())
else:
raise
class ChunkReader(object):
def __init__(self, fd, checksum, total):
self.fd = fd
self.checksum = checksum
self.total = total
self.bytes_read = 0
def read(self, i):
left = self.total - self.bytes_read
if i > left:
i = left
result = self.fd.read(i)
self.bytes_read += len(result)
self.checksum.update(result)
return result
def create_container_if_missing(container, swift_conn, conf):
"""
Creates a missing container in Swift if the
``swift_store_create_container_on_put`` option is set.
:param container: Name of container to create
:param swift_conn: Connection to Swift
:param conf: Option mapping
"""
try:
swift_conn.head_container(container)
except swift_client.ClientException, e:
if e.http_status == httplib.NOT_FOUND:
if conf.swift_store_create_container_on_put:
try:
swift_conn.put_container(container)
except ClientException, e:
msg = _("Failed to add container to Swift.\n"
"Got error from Swift: %(e)s") % locals()
raise glance.store.BackendException(msg)
else:
msg = (_("The container %(container)s does not exist in "
"Swift. Please set the "
"swift_store_create_container_on_put option"
"to add container to Swift automatically.")
% locals())
raise glance.store.BackendException(msg)
else:
raise
glance.store.register_store(__name__, ['swift', 'swift+http', 'swift+https'])
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