78 lines
2.8 KiB
Python
Executable File
78 lines
2.8 KiB
Python
Executable File
#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Utility for fetching a resource (e.g. a manifest) from a URL."""
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from oslo_log import log as logging
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import requests
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from requests import exceptions
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from six.moves import urllib
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from magnum.common import exception
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import magnum.conf
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from magnum.i18n import _
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CONF = magnum.conf.CONF
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LOG = logging.getLogger(__name__)
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class URLFetchError(exception.Invalid, IOError):
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pass
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def get(url, allowed_schemes=('http', 'https')):
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"""Get the data at the specified URL.
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The URL must use the http: or https: schemes.
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The file: scheme is also supported if you override
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the allowed_schemes argument.
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Raise an IOError if getting the data fails.
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"""
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LOG.info('Fetching data from %s', url)
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components = urllib.parse.urlparse(url)
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if components.scheme not in allowed_schemes:
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raise URLFetchError(_('Invalid URL scheme %s') % components.scheme)
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if components.scheme == 'file': # nosec
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try:
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return urllib.request.urlopen(url).read()
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except urllib.error.URLError as uex:
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raise URLFetchError(_('Failed to retrieve manifest: %s') % uex)
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try:
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resp = requests.get(url, stream=True)
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resp.raise_for_status()
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# We cannot use resp.text here because it would download the
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# entire file, and a large enough file would bring down the
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# engine. The 'Content-Length' header could be faked, so it's
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# necessary to download the content in chunks to until
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# max_manifest_size is reached. The chunk_size we use needs
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# to balance CPU-intensive string concatenation with accuracy
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# (eg. it's possible to fetch 1000 bytes greater than
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# max_manifest_size with a chunk_size of 1000).
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reader = resp.iter_content(chunk_size=1000)
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result = ""
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for chunk in reader:
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result += chunk
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if len(result) > CONF.max_manifest_size:
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raise URLFetchError("Manifest exceeds maximum allowed "
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"size (%s bytes)" %
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CONF.max_manifest_size)
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return result
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except exceptions.RequestException as ex:
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raise URLFetchError(_('Failed to retrieve manifest: %s') % ex)
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