Account ID endpoint routing

.changes/next-release/feature-endpoints-57979.json

@@ -0,0 +1,5 @@
+{
+  "type": "feature",
+  "category": "endpoints",
+  "description": "Adds support for account ID endpoint routing"
+}

botocore/args.py

@@ -25,6 +25,7 @@
 import botocore.serialize
 from botocore.config import Config
 from botocore.endpoint import EndpointCreator
+from botocore.regions import CredentialBuiltinResolver, EndpointBuiltinResolver
 from botocore.regions import EndpointResolverBuiltins as EPRBuiltins
 from botocore.regions import EndpointRulesetResolver
 from botocore.signers import RequestSigner
@@ -152,7 +153,9 @@ def get_client_args(
             protocol, parameter_validation
         )
         response_parser = botocore.parsers.create_parser(protocol)
-
+        builtin_resolver = self._construct_builtin_resolver(
+            credentials, new_config
+        )
         ruleset_resolver = self._build_endpoint_resolver(
             endpoints_ruleset_data,
             partition_data,
@@ -165,6 +168,7 @@ def get_client_args(
             is_secure,
             endpoint_bridge,
             event_emitter,
+            builtin_resolver,
         )
 
         # Copy the session's user agent factory and adds client configuration.
@@ -267,11 +271,15 @@ def compute_client_args(
                     client_config.disable_request_compression
                 ),
                 client_context_params=client_config.client_context_params,
+                account_id_endpoint_mode=(
+                    client_config.account_id_endpoint_mode
+                ),
             )
         self._compute_retry_config(config_kwargs)
         self._compute_connect_timeout(config_kwargs)
         self._compute_user_agent_appid_config(config_kwargs)
         self._compute_request_compression_config(config_kwargs)
+        self._compute_account_id_endpoint_mode(config_kwargs)
         s3_config = self.compute_s3_config(client_config)
 
         is_s3_service = self._is_s3_service(service_name)
@@ -598,12 +606,29 @@ def _validate_min_compression_size(self, min_size):
 
         return min_size
 
+    def _compute_account_id_endpoint_mode(self, config_kwargs):
+        ep_mode = config_kwargs.get('account_id_endpoint_mode')
+        if ep_mode is None:
+            ep_mode = self._config_store.get_config_variable(
+                'account_id_endpoint_mode'
+            )
+            config_kwargs['account_id_endpoint_mode'] = ep_mode
+
     def _ensure_boolean(self, val):
         if isinstance(val, bool):
             return val
         else:
             return val.lower() == 'true'
 
+    def _construct_builtin_resolver(self, credentials, client_config):
+        credential_builtin_resolver = CredentialBuiltinResolver(
+            credentials, client_config.account_id_endpoint_mode
+        )
+        # This only includes CredentialBuiltinResolver for now, but may grow
+        # as more endpoint builtins are added.
+        resolver_map = {'credentials': credential_builtin_resolver}
+        return EndpointBuiltinResolver(resolver_map)
+
     def _build_endpoint_resolver(
         self,
         endpoints_ruleset_data,
@@ -617,6 +642,7 @@ def _build_endpoint_resolver(
         is_secure,
         endpoint_bridge,
         event_emitter,
+        builtin_resolver,
     ):
         if endpoints_ruleset_data is None:
             return None
@@ -666,6 +692,7 @@ def _build_endpoint_resolver(
             event_emitter=event_emitter,
             use_ssl=is_secure,
             requested_auth_scheme=sig_version,
+            builtin_resolver=builtin_resolver,
         )
 
     def compute_endpoint_resolver_builtin_defaults(
@@ -750,6 +777,9 @@ def compute_endpoint_resolver_builtin_defaults(
                 's3_disable_multiregion_access_points', False
             ),
             EPRBuiltins.SDK_ENDPOINT: given_endpoint,
+            # account ID is calculated later if account based routing is
+            # enabled and configured for the service
+            EPRBuiltins.AWS_ACCOUNT_ID: None,
         }
 
     def _compute_user_agent_appid_config(self, config_kwargs):

botocore/config.py

@@ -228,7 +228,17 @@ class Config:
         documentation. Invalid parameters or ones that are not used by the
         specified service will be ignored.
 
-        Defaults to None.
+    :type account_id_endpoint_mode: str
+    :param account_id_endpoint_mode: Set account ID based endpoint behavior
+        for supported operations.
+        Valid options are:
+
+        * ``preferred`` -- Use account ID based endpoint routing if available.
+        * ``required`` -- Raise ``AccountIdNotFound`` exception if account ID
+            based endpoint routing is unavailable.
+        * ``disabled`` -- Disable account ID based endpoint routing.
+
+        If not specified, the default behavior is ``preferred``.
     """
 
     OPTION_DEFAULTS = OrderedDict(
@@ -257,6 +267,7 @@ class Config:
             ('request_min_compression_size_bytes', None),
             ('disable_request_compression', None),
             ('client_context_params', None),
+            ('account_id_endpoint_mode', None),
         ]
     )
 

botocore/configprovider.py

@@ -161,6 +161,12 @@
         False,
         utils.ensure_boolean,
     ),
+    'account_id_endpoint_mode': (
+        'account_id_endpoint_mode',
+        'AWS_ACCOUNT_ID_ENDPOINT_MODE',
+        'preferred',
+        None,
+    ),
 }
 # A mapping for the s3 specific configuration vars. These are the configuration
 # vars that typically go in the s3 section of the config file. This mapping