Container Infrastructure Management Service for OpenStack
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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
# 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.
"""Utility for fetching a resource (e.g. a manifest) from a URL."""
from oslo_log import log as logging
import requests
from requests import exceptions
from six.moves import urllib
from magnum.common import exception
import magnum.conf
from magnum.i18n import _
CONF = magnum.conf.CONF
LOG = logging.getLogger(__name__)
class URLFetchError(exception.Invalid, IOError):
def get(url, allowed_schemes=('http', 'https')):
"""Get the data at the specified URL.
The URL must use the http: or https: schemes.
The file: scheme is also supported if you override
the allowed_schemes argument.
Raise an IOError if getting the data fails.
"""'Fetching data from %s', url)
components = urllib.parse.urlparse(url)
if components.scheme not in allowed_schemes:
raise URLFetchError(_('Invalid URL scheme %s') % components.scheme)
if components.scheme == 'file': # nosec
return urllib.request.urlopen(url).read()
except urllib.error.URLError as uex:
raise URLFetchError(_('Failed to retrieve manifest: %s') % uex)
resp = requests.get(url, stream=True)
# We cannot use resp.text here because it would download the
# entire file, and a large enough file would bring down the
# engine. The 'Content-Length' header could be faked, so it's
# necessary to download the content in chunks to until
# max_manifest_size is reached. The chunk_size we use needs
# to balance CPU-intensive string concatenation with accuracy
# (eg. it's possible to fetch 1000 bytes greater than
# max_manifest_size with a chunk_size of 1000).
reader = resp.iter_content(chunk_size=1000)
result = ""
for chunk in reader:
result += chunk
if len(result) > CONF.max_manifest_size:
raise URLFetchError("Manifest exceeds maximum allowed "
"size (%s bytes)" %
return result
except exceptions.RequestException as ex:
raise URLFetchError(_('Failed to retrieve manifest: %s') % ex)