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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.
"""Utility for fetching a resource (e.g. a template) from a URL."""
from oslo_config import cfg
from oslo_log import log as logging
import requests
from requests import exceptions
from six.moves import urllib
from heat.common import exception
from heat.common.i18n import _
cfg.CONF.import_opt('max_template_size', 'heat.common.config')
LOG = logging.getLogger(__name__)
class URLFetchError(exception.Error, IOError):
pass
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.
"""
components = urllib.parse.urlparse(url)
if components.scheme not in allowed_schemes:
raise URLFetchError(_('Invalid URL scheme %s') % components.scheme)
LOG.info('Fetching data from %s', url)
if components.scheme == 'file':
try:
return urllib.request.urlopen(url).read()
except urllib.error.URLError as uex:
raise URLFetchError(_('Failed to retrieve template: %s') % uex)
try:
resp = requests.get(url, stream=True)
resp.raise_for_status()
# 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_template_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_template_size with a chunk_size of 1000).
reader = resp.iter_content(chunk_size=1000)
result = b""
for chunk in reader:
result += chunk
if len(result) > cfg.CONF.max_template_size:
raise URLFetchError(_("Template exceeds maximum allowed size "
"(%s bytes)") %
cfg.CONF.max_template_size)
return result
except exceptions.RequestException as ex:
LOG.info('Failed to retrieve template: %s', ex)
raise URLFetchError(_('Failed to retrieve template from %s') % url)
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