208 lines
9 KiB
Python
208 lines
9 KiB
Python
# Copyright 2014 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"). You
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# may not use this file except in compliance with the License. A copy of
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# the License is located at
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#
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# http://aws.amazon.com/apache2.0/
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#
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# or in the "license" file accompanying this file. This file is
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# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
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# ANY KIND, either express or implied. See the License for the specific
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# language governing permissions and limitations under the License.
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"""Resolves regions and endpoints.
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This module implements endpoint resolution, including resolving endpoints for a
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given service and region and resolving the available endpoints for a service
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in a specific AWS partition.
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"""
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import logging
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import re
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from botocore.exceptions import NoRegionError
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LOG = logging.getLogger(__name__)
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DEFAULT_URI_TEMPLATE = '{service}.{region}.{dnsSuffix}'
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DEFAULT_SERVICE_DATA = {'endpoints': {}}
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class BaseEndpointResolver(object):
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"""Resolves regions and endpoints. Must be subclassed."""
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def construct_endpoint(self, service_name, region_name=None):
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"""Resolves an endpoint for a service and region combination.
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:type service_name: string
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:param service_name: Name of the service to resolve an endpoint for
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(e.g., s3)
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:type region_name: string
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:param region_name: Region/endpoint name to resolve (e.g., us-east-1)
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if no region is provided, the first found partition-wide endpoint
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will be used if available.
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:rtype: dict
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:return: Returns a dict containing the following keys:
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- partition: (string, required) Resolved partition name
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- endpointName: (string, required) Resolved endpoint name
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- hostname: (string, required) Hostname to use for this endpoint
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- sslCommonName: (string) sslCommonName to use for this endpoint.
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- credentialScope: (dict) Signature version 4 credential scope
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- region: (string) region name override when signing.
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- service: (string) service name override when signing.
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- signatureVersions: (list<string>) A list of possible signature
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versions, including s3, v4, v2, and s3v4
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- protocols: (list<string>) A list of supported protocols
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(e.g., http, https)
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- ...: Other keys may be included as well based on the metadata
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"""
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raise NotImplementedError
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def get_available_partitions(self):
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"""Lists the partitions available to the endpoint resolver.
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:return: Returns a list of partition names (e.g., ["aws", "aws-cn"]).
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"""
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raise NotImplementedError
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def get_available_endpoints(self, service_name, partition_name='aws',
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allow_non_regional=False):
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"""Lists the endpoint names of a particular partition.
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:type service_name: string
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:param service_name: Name of a service to list endpoint for (e.g., s3)
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:type partition_name: string
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:param partition_name: Name of the partition to limit endpoints to.
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(e.g., aws for the public AWS endpoints, aws-cn for AWS China
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endpoints, aws-us-gov for AWS GovCloud (US) Endpoints, etc.
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:type allow_non_regional: bool
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:param allow_non_regional: Set to True to include endpoints that are
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not regional endpoints (e.g., s3-external-1,
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fips-us-gov-west-1, etc).
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:return: Returns a list of endpoint names (e.g., ["us-east-1"]).
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"""
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raise NotImplementedError
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class EndpointResolver(BaseEndpointResolver):
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"""Resolves endpoints based on partition endpoint metadata"""
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def __init__(self, endpoint_data):
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"""
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:param endpoint_data: A dict of partition data.
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"""
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if 'partitions' not in endpoint_data:
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raise ValueError('Missing "partitions" in endpoint data')
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self._endpoint_data = endpoint_data
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def get_available_partitions(self):
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result = []
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for partition in self._endpoint_data['partitions']:
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result.append(partition['partition'])
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return result
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def get_available_endpoints(self, service_name, partition_name='aws',
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allow_non_regional=False):
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result = []
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for partition in self._endpoint_data['partitions']:
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if partition['partition'] != partition_name:
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continue
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services = partition['services']
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if service_name not in services:
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continue
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for endpoint_name in services[service_name]['endpoints']:
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if allow_non_regional or endpoint_name in partition['regions']:
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result.append(endpoint_name)
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return result
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def get_partition_dns_suffix(self, partition_name):
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for partition in self._endpoint_data['partitions']:
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if partition['partition'] == partition_name:
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return partition['dnsSuffix']
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return None
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def construct_endpoint(self, service_name, region_name=None, partition_name=None):
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if partition_name is not None:
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valid_partition = None
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for partition in self._endpoint_data['partitions']:
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if partition['partition'] == partition_name:
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valid_partition = partition
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if valid_partition is not None:
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result = self._endpoint_for_partition(valid_partition, service_name,
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region_name, True)
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return result
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return None
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# Iterate over each partition until a match is found.
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for partition in self._endpoint_data['partitions']:
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result = self._endpoint_for_partition(
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partition, service_name, region_name)
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if result:
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return result
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def _endpoint_for_partition(self, partition, service_name, region_name,
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force_partition=False):
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# Get the service from the partition, or an empty template.
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service_data = partition['services'].get(
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service_name, DEFAULT_SERVICE_DATA)
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# Use the partition endpoint if no region is supplied.
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if region_name is None:
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if 'partitionEndpoint' in service_data:
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region_name = service_data['partitionEndpoint']
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else:
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raise NoRegionError()
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# Attempt to resolve the exact region for this partition.
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if region_name in service_data['endpoints']:
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return self._resolve(
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partition, service_name, service_data, region_name)
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# Check to see if the endpoint provided is valid for the partition.
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if self._region_match(partition, region_name) or force_partition:
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# Use the partition endpoint if set and not regionalized.
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partition_endpoint = service_data.get('partitionEndpoint')
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is_regionalized = service_data.get('isRegionalized', True)
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if partition_endpoint and not is_regionalized:
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LOG.debug('Using partition endpoint for %s, %s: %s',
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service_name, region_name, partition_endpoint)
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return self._resolve(
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partition, service_name, service_data, partition_endpoint)
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LOG.debug('Creating a regex based endpoint for %s, %s',
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service_name, region_name)
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return self._resolve(
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partition, service_name, service_data, region_name)
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def _region_match(self, partition, region_name):
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if region_name in partition['regions']:
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return True
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if 'regionRegex' in partition:
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return re.compile(partition['regionRegex']).match(region_name)
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return False
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def _resolve(self, partition, service_name, service_data, endpoint_name):
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result = service_data['endpoints'].get(endpoint_name, {})
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result['partition'] = partition['partition']
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result['endpointName'] = endpoint_name
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# Merge in the service defaults then the partition defaults.
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self._merge_keys(service_data.get('defaults', {}), result)
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self._merge_keys(partition.get('defaults', {}), result)
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hostname = result.get('hostname', DEFAULT_URI_TEMPLATE)
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result['hostname'] = self._expand_template(
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partition, result['hostname'], service_name, endpoint_name)
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if 'sslCommonName' in result:
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result['sslCommonName'] = self._expand_template(
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partition, result['sslCommonName'], service_name,
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endpoint_name)
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result['dnsSuffix'] = partition['dnsSuffix']
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return result
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def _merge_keys(self, from_data, result):
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for key in from_data:
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if key not in result:
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result[key] = from_data[key]
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def _expand_template(self, partition, template, service_name,
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endpoint_name):
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return template.format(
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service=service_name, region=endpoint_name,
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dnsSuffix=partition['dnsSuffix'])
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