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# Copyright 2014 Amazon.com, Inc. or its affiliates. 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. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file 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.
"""Resolves regions and endpoints.
This module implements endpoint resolution, including resolving endpoints for a
given service and region and resolving the available endpoints for a service
in a specific AWS partition.
"""
import logging
import re
from botocore.exceptions import NoRegionError
LOG = logging.getLogger(__name__)
DEFAULT_URI_TEMPLATE = '{service}.{region}.{dnsSuffix}'
DEFAULT_SERVICE_DATA = {'endpoints': {}}
class BaseEndpointResolver(object):
"""Resolves regions and endpoints. Must be subclassed."""
def construct_endpoint(self, service_name, region_name=None):
"""Resolves an endpoint for a service and region combination.
:type service_name: string
:param service_name: Name of the service to resolve an endpoint for
(e.g., s3)
:type region_name: string
:param region_name: Region/endpoint name to resolve (e.g., us-east-1)
if no region is provided, the first found partition-wide endpoint
will be used if available.
:rtype: dict
:return: Returns a dict containing the following keys:
- partition: (string, required) Resolved partition name
- endpointName: (string, required) Resolved endpoint name
- hostname: (string, required) Hostname to use for this endpoint
- sslCommonName: (string) sslCommonName to use for this endpoint.
- credentialScope: (dict) Signature version 4 credential scope
- region: (string) region name override when signing.
- service: (string) service name override when signing.
- signatureVersions: (list<string>) A list of possible signature
versions, including s3, v4, v2, and s3v4
- protocols: (list<string>) A list of supported protocols
(e.g., http, https)
- ...: Other keys may be included as well based on the metadata
"""
raise NotImplementedError
def get_available_partitions(self):
"""Lists the partitions available to the endpoint resolver.
:return: Returns a list of partition names (e.g., ["aws", "aws-cn"]).
"""
raise NotImplementedError
def get_available_endpoints(self, service_name, partition_name='aws',
allow_non_regional=False):
"""Lists the endpoint names of a particular partition.
:type service_name: string
:param service_name: Name of a service to list endpoint for (e.g., s3)
:type partition_name: string
:param partition_name: Name of the partition to limit endpoints to.
(e.g., aws for the public AWS endpoints, aws-cn for AWS China
endpoints, aws-us-gov for AWS GovCloud (US) Endpoints, etc.
:type allow_non_regional: bool
:param allow_non_regional: Set to True to include endpoints that are
not regional endpoints (e.g., s3-external-1,
fips-us-gov-west-1, etc).
:return: Returns a list of endpoint names (e.g., ["us-east-1"]).
"""
raise NotImplementedError
class EndpointResolver(BaseEndpointResolver):
"""Resolves endpoints based on partition endpoint metadata"""
def __init__(self, endpoint_data):
"""
:param endpoint_data: A dict of partition data.
"""
if 'partitions' not in endpoint_data:
raise ValueError('Missing "partitions" in endpoint data')
self._endpoint_data = endpoint_data
def get_available_partitions(self):
result = []
for partition in self._endpoint_data['partitions']:
result.append(partition['partition'])
return result
def get_available_endpoints(self, service_name, partition_name='aws',
allow_non_regional=False):
result = []
for partition in self._endpoint_data['partitions']:
if partition['partition'] != partition_name:
continue
services = partition['services']
if service_name not in services:
continue
for endpoint_name in services[service_name]['endpoints']:
if allow_non_regional or endpoint_name in partition['regions']:
result.append(endpoint_name)
return result
def construct_endpoint(self, service_name, region_name=None):
# Iterate over each partition until a match is found.
for partition in self._endpoint_data['partitions']:
result = self._endpoint_for_partition(
partition, service_name, region_name)
if result:
return result
def _endpoint_for_partition(self, partition, service_name, region_name):
# Get the service from the partition, or an empty template.
service_data = partition['services'].get(
service_name, DEFAULT_SERVICE_DATA)
# Use the partition endpoint if no region is supplied.
if region_name is None:
if 'partitionEndpoint' in service_data:
region_name = service_data['partitionEndpoint']
else:
raise NoRegionError()
# Attempt to resolve the exact region for this partition.
if region_name in service_data['endpoints']:
return self._resolve(
partition, service_name, service_data, region_name)
# Check to see if the endpoint provided is valid for the partition.
if self._region_match(partition, region_name):
# Use the partition endpoint if set and not regionalized.
partition_endpoint = service_data.get('partitionEndpoint')
is_regionalized = service_data.get('isRegionalized', True)
if partition_endpoint and not is_regionalized:
LOG.debug('Using partition endpoint for %s, %s: %s',
service_name, region_name, partition_endpoint)
return self._resolve(
partition, service_name, service_data, partition_endpoint)
LOG.debug('Creating a regex based endpoint for %s, %s',
service_name, region_name)
return self._resolve(
partition, service_name, service_data, region_name)
def _region_match(self, partition, region_name):
if region_name in partition['regions']:
return True
if 'regionRegex' in partition:
return re.compile(partition['regionRegex']).match(region_name)
return False
def _resolve(self, partition, service_name, service_data, endpoint_name):
result = service_data['endpoints'].get(endpoint_name, {})
result['partition'] = partition['partition']
result['endpointName'] = endpoint_name
# Merge in the service defaults then the partition defaults.
self._merge_keys(service_data.get('defaults', {}), result)
self._merge_keys(partition.get('defaults', {}), result)
hostname = result.get('hostname', DEFAULT_URI_TEMPLATE)
result['hostname'] = self._expand_template(
partition, result['hostname'], service_name, endpoint_name)
if 'sslCommonName' in result:
result['sslCommonName'] = self._expand_template(
partition, result['sslCommonName'], service_name,
endpoint_name)
result['dnsSuffix'] = partition['dnsSuffix']
return result
def _merge_keys(self, from_data, result):
for key in from_data:
if key not in result:
result[key] = from_data[key]
def _expand_template(self, partition, template, service_name,
endpoint_name):
return template.format(
service=service_name, region=endpoint_name,
dnsSuffix=partition['dnsSuffix'])
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