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OpenStack Study: glance.py

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# 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.

"""Implementation of an image service that uses Glance as the backend"""

from __future__ import absolute_import

import glanceclient.exc

from oslo.config import cfg

import six.moves.urllib.parse as urlparse

from cinder import exception

from cinder.openstack.common import jsonutils

from cinder.openstack.common import log as logging

from cinder.openstack.common import timeutils

glance_opts = [

cfg.ListOpt('allowed_direct_url_schemes',

default=[],

help='A list of url schemes that can be downloaded directly '

'via the direct_url. Currently supported schemes: '

'[file].'),

]

CONF = cfg.CONF

CONF.register_opts(glance_opts)

CONF.import_opt('glance_api_version', 'cinder.common.config')

LOG = logging.getLogger(__name__)

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def _parse_image_ref(image_href):

"""Parse an image href into composite parts.

:param image_href: href of an image

:returns: a tuple of the form (image_id, netloc, use_ssl)

:raises ValueError

"""

url = urlparse.urlparse(image_href)

netloc = url.netloc

image_id = url.path.split('/')[-1]

use_ssl = (url.scheme == 'https')

return (image_id, netloc, use_ssl)

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def _create_glance_client(context, netloc, use_ssl,

version=CONF.glance_api_version):

"""Instantiate a new glanceclient.Client object."""

if version is None:

version = CONF.glance_api_version

params = {}

if use_ssl:

scheme = 'https'

# https specific params

params['insecure'] = CONF.glance_api_insecure

params['ssl_compression'] = CONF.glance_api_ssl_compression

else:

scheme = 'http'

if CONF.auth_strategy == 'keystone':

params['token'] = context.auth_token

if CONF.glance_request_timeout is not None:

params['timeout'] = CONF.glance_request_timeout

endpoint = '%s://%s' % (scheme, netloc)

return glanceclient.Client(str(version), endpoint, **params)

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def get_api_servers():

"""Return Iterable over shuffled api servers.

Shuffle a list of CONF.glance_api_servers and return an iterator

that will cycle through the list, looping around to the beginning

if necessary.

"""

api_servers = []

for api_server in CONF.glance_api_servers:

if '//' not in api_server:

api_server = 'http://' + api_server

url = urlparse.urlparse(api_server)

netloc = url.netloc

use_ssl = (url.scheme == 'https')

api_servers.append((netloc, use_ssl))

random.shuffle(api_servers)

return itertools.cycle(api_servers)

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class GlanceClientWrapper(object):

"""Glance client wrapper class that implements retries."""

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def __init__(self, context=None, netloc=None, use_ssl=False,

version=None):

if netloc is not None:

self.client = self._create_static_client(context,

self.api_servers = None

self.version = version

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def _create_static_client(self, context, netloc, use_ssl, version):

"""Create a client that we'll use for every call."""

self.netloc = netloc

self.use_ssl = use_ssl

self.version = version

return _create_glance_client(context,

self.netloc,

self.use_ssl, self.version)

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def _create_onetime_client(self, context, version):

"""Create a client that will be used for one call."""

if self.api_servers is None:

self.api_servers = get_api_servers()

self.netloc, self.use_ssl = self.api_servers.next()

return _create_glance_client(context,

self.netloc,

self.use_ssl, version)

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def call(self, context, method, *args, **kwargs):

"""Call a glance client method.

If we get a connection error,

retry the request according to CONF.glance_num_retries.

"""

version = self.version

if version in kwargs:

version = kwargs['version']

retry_excs = (glanceclient.exc.ServiceUnavailable,

glanceclient.exc.InvalidEndpoint,

glanceclient.exc.CommunicationError)

num_attempts = 1 + CONF.glance_num_retries

for attempt in xrange(1, num_attempts + 1):

client = self.client or self._create_onetime_client(context,

version)

try:

return getattr(client.images, method)(*args, **kwargs)

except retry_excs as e:

netloc = self.netloc

extra = "retrying"

error_msg = _("Error contacting glance server "

"'%(netloc)s' for '%(method)s', "

"%(extra)s.") % {'netloc': netloc,

'method': method,

'extra': extra,

}

if attempt == num_attempts:

extra = 'done trying'

error_msg = _("Error contacting glance server "

"'%(netloc)s' for '%(method)s', "

"%(extra)s.") % {'netloc': netloc,

'method': method,

'extra': extra,

}

LOG.exception(error_msg)

raise exception.GlanceConnectionFailed(reason=e)

LOG.exception(error_msg)

time.sleep(1)

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class GlanceImageService(object):

"""Provides storage and retrieval of disk image objects within Glance."""

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def __init__(self, client=None):

self._client = client or GlanceClientWrapper()

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def detail(self, context, **kwargs):

"""Calls out to Glance for a list of detailed image information."""

params = self._extract_query_params(kwargs)

try:

images = self._client.call(context, 'list', **params)

except Exception:

_reraise_translated_exception()

_images = []

for image in images:

if self._is_image_available(context, image):

_images.append(self._translate_from_glance(image))

return _images

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def _extract_query_params(self, params):

_params = {}

accepted_params = ('filters', 'marker', 'limit',

'sort_key', 'sort_dir')

for param in accepted_params:

if param in params:

_params[param] = params.get(param)

# ensure filters is a dict

_params.setdefault('filters', {})

# NOTE(vish): don't filter out private images

_params['filters'].setdefault('is_public', 'none')

return _params

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def show(self, context, image_id):

"""Returns a dict with image data for the given opaque image id."""

try:

image = self._client.call(context, 'get', image_id)

except Exception:

_reraise_translated_image_exception(image_id)

if not self._is_image_available(context, image):

raise exception.ImageNotFound(image_id=image_id)

base_image_meta = self._translate_from_glance(image)

return base_image_meta

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def get_location(self, context, image_id):

"""Returns the direct url representing the backend storage location,

or None if this attribute is not shown by Glance.

"""

if CONF.glance_api_version == 1:

# image location not available in v1

return (None, None)

try:

# direct_url is returned by v2 api

client = GlanceClientWrapper(version=2)

image_meta = client.call(context, 'get', image_id)

except Exception:

_reraise_translated_image_exception(image_id)

if not self._is_image_available(context, image_meta):

raise exception.ImageNotFound(image_id=image_id)

# some glance stores like nfs only meta data

# is stored and returned as locations.

# so composite of two needs to be returned.

return (getattr(image_meta, 'direct_url', None),

getattr(image_meta, 'locations', None))

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def download(self, context, image_id, data=None):

"""Calls out to Glance for data and writes data."""

if 'file' in CONF.allowed_direct_url_schemes:

location = self.get_location(context, image_id)

o = urlparse.urlparse(location)

if o.scheme == "file":

with open(o.path, "r") as f:

# a system call to cp could have significant performance

# advantages, however we do not have the path to files at

# this point in the abstraction.

shutil.copyfileobj(f, data)

return

try:

image_chunks = self._client.call(context, 'data', image_id)

except Exception:

_reraise_translated_image_exception(image_id)

if not data:

return image_chunks

else:

for chunk in image_chunks:

data.write(chunk)

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def create(self, context, image_meta, data=None):

"""Store the image data and return the new image object."""

sent_service_image_meta = self._translate_to_glance(image_meta)

if data:

sent_service_image_meta['data'] = data

recv_service_image_meta = self._client.call(context, 'create',

**sent_service_image_meta)

return self._translate_from_glance(recv_service_image_meta)

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def update(self, context, image_id,

image_meta, data=None, purge_props=True):

"""Modify the given image with the new data."""

image_meta = self._translate_to_glance(image_meta)

#NOTE(dosaboy): see comment in bug 1210467

if CONF.glance_api_version == 1:

image_meta['purge_props'] = purge_props

#NOTE(bcwaldon): id is not an editable field, but it is likely to be

# passed in by calling code. Let's be nice and ignore it.

image_meta.pop('id', None)

if data:

image_meta['data'] = data

try:

#NOTE(dosaboy): the v2 api separates update from upload

if data and CONF.glance_api_version > 1:

image_meta = self._client.call(context, 'upload', image_id,

image_meta['data'])

else:

image_meta = self._client.call(context, 'update', image_id,

**image_meta)

except Exception:

_reraise_translated_image_exception(image_id)

else:

return self._translate_from_glance(image_meta)

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def delete(self, context, image_id):

"""Delete the given image.

:raises: ImageNotFound if the image does not exist.

:raises: NotAuthorized if the user is not an owner.

"""

try:

self._client.call(context, 'delete', image_id)

except glanceclient.exc.NotFound:

raise exception.ImageNotFound(image_id=image_id)

return True

@staticmethod

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def _translate_to_glance(image_meta):

image_meta = _convert_to_string(image_meta)

image_meta = _remove_read_only(image_meta)

return image_meta

@staticmethod

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def _translate_from_glance(image):

image_meta = _extract_attributes(image)

image_meta = _convert_timestamps_to_datetimes(image_meta)

image_meta = _convert_from_string(image_meta)

return image_meta

@staticmethod

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def _is_image_available(context, image):

"""Check image availability.

This check is needed in case Nova and Glance are deployed

without authentication turned on.

"""

# The presence of an auth token implies this is an authenticated

# request and we need not handle the noauth use-case.

if hasattr(context, 'auth_token') and context.auth_token:

return True

if image.is_public or context.is_admin:

return True

properties = image.properties

if context.project_id and ('owner_id' in properties):

return str(properties['owner_id']) == str(context.project_id)

if context.project_id and ('project_id' in properties):

return str(properties['project_id']) == str(context.project_id)

try:

user_id = properties['user_id']

except KeyError:

return False

return str(user_id) == str(context.user_id)

def _convert_timestamps_to_datetimes(image_meta):

"""Returns image with timestamp fields converted to datetime objects."""

for attr in ['created_at', 'updated_at', 'deleted_at']:

if image_meta.get(attr):

image_meta[attr] = timeutils.parse_isotime(image_meta[attr])

return image_meta

# NOTE(bcwaldon): used to store non-string data in glance metadata

def _json_loads(properties, attr):

prop = properties[attr]

if isinstance(prop, basestring):

properties[attr] = jsonutils.loads(prop)

def _json_dumps(properties, attr):

prop = properties[attr]

if not isinstance(prop, basestring):

properties[attr] = jsonutils.dumps(prop)

_CONVERT_PROPS = ('block_device_mapping', 'mappings')

def _convert(method, metadata):

metadata = copy.deepcopy(metadata)

properties = metadata.get('properties')

if properties:

for attr in _CONVERT_PROPS:

if attr in properties:

method(properties, attr)

return metadata

def _convert_from_string(metadata):

return _convert(_json_loads, metadata)

def _convert_to_string(metadata):

return _convert(_json_dumps, metadata)

def _extract_attributes(image):

#NOTE(hdd): If a key is not found, base.Resource.__getattr__() may perform

# a get(), resulting in a useless request back to glance. This list is

# therefore sorted, with dependent attributes as the end

# 'deleted_at' depends on 'deleted'

# 'checksum' depends on 'status' == 'active'

IMAGE_ATTRIBUTES = ['size', 'disk_format', 'owner',

'container_format', 'status', 'id',

'name', 'created_at', 'updated_at',

'deleted', 'deleted_at', 'checksum',

'min_disk', 'min_ram', 'is_public']

output = {}

for attr in IMAGE_ATTRIBUTES:

if attr == 'deleted_at' and not output['deleted']:

output[attr] = None

elif attr == 'checksum' and output['status'] != 'active':

output[attr] = None

else:

output[attr] = getattr(image, attr)

output['properties'] = getattr(image, 'properties', {})

return output

def _remove_read_only(image_meta):

IMAGE_ATTRIBUTES = ['status', 'updated_at', 'created_at', 'deleted_at']

output = copy.deepcopy(image_meta)

for attr in IMAGE_ATTRIBUTES:

if attr in output:

del output[attr]

return output

def _reraise_translated_image_exception(image_id):

"""Transform the exception for the image but keep its traceback intact."""

exc_type, exc_value, exc_trace = sys.exc_info()

new_exc = _translate_image_exception(image_id, exc_value)

raise new_exc, None, exc_trace

def _reraise_translated_exception():

"""Transform the exception but keep its traceback intact."""

exc_type, exc_value, exc_trace = sys.exc_info()

new_exc = _translate_plain_exception(exc_value)

raise new_exc, None, exc_trace

def _translate_image_exception(image_id, exc_value):

if isinstance(exc_value, (glanceclient.exc.Forbidden,

glanceclient.exc.Unauthorized)):

return exception.ImageNotAuthorized(image_id=image_id)

if isinstance(exc_value, glanceclient.exc.NotFound):

return exception.ImageNotFound(image_id=image_id)

if isinstance(exc_value, glanceclient.exc.BadRequest):

return exception.Invalid(exc_value)

return exc_value

def _translate_plain_exception(exc_value):

if isinstance(exc_value, (glanceclient.exc.Forbidden,

glanceclient.exc.Unauthorized)):

return exception.NotAuthorized(exc_value)

if isinstance(exc_value, glanceclient.exc.NotFound):

return exception.NotFound(exc_value)

if isinstance(exc_value, glanceclient.exc.BadRequest):

return exception.Invalid(exc_value)

return exc_value

def get_remote_image_service(context, image_href):

"""Create an image_service and parse the id from the given image_href.

The image_href param can be an href of the form

'http://example.com:9292/v1/images/b8b2c6f7-7345-4e2f-afa2-eedaba9cbbe3',

or just an id such as 'b8b2c6f7-7345-4e2f-afa2-eedaba9cbbe3'. If the

image_href is a standalone id, then the default image service is returned.

:param image_href: href that describes the location of an image

:returns: a tuple of the form (image_service, image_id)

"""

#NOTE(bcwaldon): If image_href doesn't look like a URI, assume its a

# standalone image ID

if '/' not in str(image_href):

image_service = get_default_image_service()

return image_service, image_href

try:

(image_id, glance_netloc, use_ssl) = _parse_image_ref(image_href)

glance_client = GlanceClientWrapper(context=context,

netloc=glance_netloc,

use_ssl=use_ssl)

except ValueError:

raise exception.InvalidImageRef(image_href=image_href)

image_service = GlanceImageService(client=glance_client)

return image_service, image_id

def get_default_image_service():

return GlanceImageService()

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def _convert_timestamps_to_datetimes(image_meta):

"""Returns image with timestamp fields converted to datetime objects."""

for attr in ['created_at', 'updated_at', 'deleted_at']:

if image_meta.get(attr):

image_meta[attr] = timeutils.parse_isotime(image_meta[attr])

return image_meta

# NOTE(bcwaldon): used to store non-string data in glance metadata

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def _json_loads(properties, attr):

prop = properties[attr]

if isinstance(prop, basestring):

properties[attr] = jsonutils.loads(prop)

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def _json_dumps(properties, attr):

prop = properties[attr]

if not isinstance(prop, basestring):

properties[attr] = jsonutils.dumps(prop)

_CONVERT_PROPS = ('block_device_mapping', 'mappings')

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def _convert(method, metadata):

metadata = copy.deepcopy(metadata)

properties = metadata.get('properties')

if properties:

for attr in _CONVERT_PROPS:

if attr in properties:

method(properties, attr)

return metadata

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def _convert_from_string(metadata):

return _convert(_json_loads, metadata)

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def _convert_to_string(metadata):

return _convert(_json_dumps, metadata)

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def _extract_attributes(image):

#NOTE(hdd): If a key is not found, base.Resource.__getattr__() may perform

# a get(), resulting in a useless request back to glance. This list is

# therefore sorted, with dependent attributes as the end

# 'deleted_at' depends on 'deleted'

# 'checksum' depends on 'status' == 'active'

IMAGE_ATTRIBUTES = ['size', 'disk_format', 'owner',

'container_format', 'status', 'id',

'name', 'created_at', 'updated_at',

'deleted', 'deleted_at', 'checksum',

'min_disk', 'min_ram', 'is_public']

output = {}

for attr in IMAGE_ATTRIBUTES:

if attr == 'deleted_at' and not output['deleted']:

output[attr] = None

elif attr == 'checksum' and output['status'] != 'active':

output[attr] = None

else:

output[attr] = getattr(image, attr)

output['properties'] = getattr(image, 'properties', {})

return output

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def _remove_read_only(image_meta):

IMAGE_ATTRIBUTES = ['status', 'updated_at', 'created_at', 'deleted_at']

output = copy.deepcopy(image_meta)

for attr in IMAGE_ATTRIBUTES:

if attr in output:

del output[attr]

return output

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def _reraise_translated_image_exception(image_id):

"""Transform the exception for the image but keep its traceback intact."""

exc_type, exc_value, exc_trace = sys.exc_info()

new_exc = _translate_image_exception(image_id, exc_value)

raise new_exc, None, exc_trace

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def _reraise_translated_exception():

"""Transform the exception but keep its traceback intact."""

exc_type, exc_value, exc_trace = sys.exc_info()

new_exc = _translate_plain_exception(exc_value)

raise new_exc, None, exc_trace

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def _translate_image_exception(image_id, exc_value):

if isinstance(exc_value, (glanceclient.exc.Forbidden,

glanceclient.exc.Unauthorized)):

return exception.ImageNotAuthorized(image_id=image_id)

if isinstance(exc_value, glanceclient.exc.NotFound):

return exception.ImageNotFound(image_id=image_id)

if isinstance(exc_value, glanceclient.exc.BadRequest):

return exception.Invalid(exc_value)

return exc_value

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def _translate_plain_exception(exc_value):

if isinstance(exc_value, (glanceclient.exc.Forbidden,

glanceclient.exc.Unauthorized)):

return exception.NotAuthorized(exc_value)

if isinstance(exc_value, glanceclient.exc.NotFound):

return exception.NotFound(exc_value)

if isinstance(exc_value, glanceclient.exc.BadRequest):

return exception.Invalid(exc_value)

return exc_value

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def get_remote_image_service(context, image_href):

"""Create an image_service and parse the id from the given image_href.

The image_href param can be an href of the form

'http://example.com:9292/v1/images/b8b2c6f7-7345-4e2f-afa2-eedaba9cbbe3',

or just an id such as 'b8b2c6f7-7345-4e2f-afa2-eedaba9cbbe3'. If the

image_href is a standalone id, then the default image service is returned.

:param image_href: href that describes the location of an image

:returns: a tuple of the form (image_service, image_id)

"""

#NOTE(bcwaldon): If image_href doesn't look like a URI, assume its a

# standalone image ID

if '/' not in str(image_href):

image_service = get_default_image_service()

return image_service, image_href

try:

(image_id, glance_netloc, use_ssl) = _parse_image_ref(image_href)

glance_client = GlanceClientWrapper(context=context,

netloc=glance_netloc,

use_ssl=use_ssl)

except ValueError:

raise exception.InvalidImageRef(image_href=image_href)

image_service = GlanceImageService(client=glance_client)

return image_service, image_id

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def get_default_image_service():

return GlanceImageService()