feat: restructure client supplier configuration

Author: mattsb42-aws

src/aws_encryption_sdk/keyrings/aws_kms/__init__.py

@@ -19,10 +19,12 @@
 from aws_encryption_sdk.materials_managers import DecryptionMaterials, EncryptionMaterials
 from aws_encryption_sdk.structures import EncryptedDataKey, KeyringTrace, KeyringTraceFlag, MasterKeyInfo, RawDataKey
 
-from .client_suppliers import ClientSupplier, DefaultClientSupplier
+from .client_suppliers import DefaultClientSupplier
+
+from .client_suppliers import ClientSupplier  # noqa - only used in docstring params; this confuses flake8
 
 try:  # Python 3.5.0 and 3.5.1 have incompatible typing modules
-    from typing import Any, Dict, Iterable, Union  # noqa pylint: disable=unused-import
+    from typing import Dict, Iterable, Union  # noqa pylint: disable=unused-import
     from .client_suppliers import ClientSupplierType  # noqa pylint: disable=unused-import
 except ImportError:  # pragma: no cover
     # We only actually need these imports when running the mypy checks

src/aws_encryption_sdk/keyrings/aws_kms/client_suppliers.py

@@ -9,23 +9,30 @@
 
 import attr
 import six
-from attr.validators import deep_iterable, instance_of
+from attr.validators import deep_iterable, instance_of, optional
 from botocore.client import BaseClient
-from botocore.session import Session as BotocoreSession
 
 from aws_encryption_sdk.exceptions import UnknownRegionError
 from aws_encryption_sdk.internal.validators import value_is_not_a_string
 
 from .client_cache import ClientCache
 
 try:  # Python 3.5.0 and 3.5.1 have incompatible typing modules
-    from typing import Any, Dict, Union  # noqa pylint: disable=unused-import
+    from typing import Callable, Union  # noqa pylint: disable=unused-import
+
+    ClientSupplierType = Callable[[Union[None, str]], BaseClient]
 except ImportError:  # pragma: no cover
     # We only actually need these imports when running the mypy checks
     pass
 
 _LOGGER = logging.getLogger(__name__)
-__all__ = ("ClientSupplier", "DefaultClientSupplier", "AllowRegionsClientSupplier", "DenyRegionsClientSupplier")
+__all__ = (
+    "ClientSupplier",
+    "ClientSupplierType",
+    "DefaultClientSupplier",
+    "AllowRegionsClientSupplier",
+    "DenyRegionsClientSupplier",
+)
 
 
 class ClientSupplier(object):
@@ -55,19 +62,15 @@ class DefaultClientSupplier(ClientSupplier):
     :type botocore_session: botocore.session.Session
     """
 
-    _botocore_session = attr.ib(default=attr.Factory(BotocoreSession), validator=instance_of(BotocoreSession))
-
-    def __attrs_post_init__(self):
-        """Set up internal client cache."""
-        self._cache = ClientCache(botocore_session=self._botocore_session)
+    _client_cache = attr.ib(default=attr.Factory(ClientCache), validator=instance_of(ClientCache))
 
     def __call__(self, region_name):
         # type: (Union[None, str]) -> BaseClient
         """Return a client for the requested region.
 
         :rtype: BaseClient
         """
-        return self._cache.client(region_name=region_name, service="kms")
+        return self._client_cache.client(region_name=region_name, service="kms")
 
 
 @attr.s
@@ -77,20 +80,17 @@ class AllowRegionsClientSupplier(ClientSupplier):
     .. versionadded:: 1.5.0
 
     :param List[str] allowed_regions: Regions to allow
-    :param botocore_session: botocore session to use when creating clients (optional)
-    :type botocore_session: botocore.session.Session
+    :param ClientSupplier client_supplier: Client supplier to wrap (optional)
     """
 
     allowed_regions = attr.ib(
         validator=(deep_iterable(member_validator=instance_of(six.string_types)), value_is_not_a_string)
     )
-    _botocore_session = attr.ib(default=attr.Factory(BotocoreSession), validator=instance_of(BotocoreSession))
-
-    def __attrs_post_init__(self):
-        """Set up internal client supplier."""
-        self._supplier = DefaultClientSupplier(botocore_session=self._botocore_session)
+    _client_supplier = attr.ib(
+        default=attr.Factory(DefaultClientSupplier), validator=optional(instance_of(ClientSupplier))
+    )
 
-    def client(self, region_name):
+    def __call__(self, region_name):
         # type: (Union[None, str]) -> BaseClient
         """Return a client for the requested region.
 
@@ -100,7 +100,7 @@ def client(self, region_name):
         if region_name not in self.allowed_regions:
             raise UnknownRegionError("Unable to provide client for region '{}'".format(region_name))
 
-        return self._supplier(region_name)
+        return self._client_supplier(region_name)
 
 
 @attr.s
@@ -110,18 +110,15 @@ class DenyRegionsClientSupplier(ClientSupplier):
     .. versionadded:: 1.5.0
 
     :param List[str] denied_regions: Regions to deny
-    :param botocore_session: Botocore session to use when creating clients (optional)
-    :type botocore_session: botocore.session.Session
+    :param ClientSupplier client_supplier: Client supplier to wrap (optional)
     """
 
     denied_regions = attr.ib(
         validator=(deep_iterable(member_validator=instance_of(six.string_types)), value_is_not_a_string)
     )
-    _botocore_session = attr.ib(default=attr.Factory(BotocoreSession), validator=instance_of(BotocoreSession))
-
-    def __attrs_post_init__(self):
-        """Set up internal client supplier."""
-        self._supplier = DefaultClientSupplier(botocore_session=self._botocore_session)
+    _client_supplier = attr.ib(
+        default=attr.Factory(DefaultClientSupplier), validator=optional(instance_of(ClientSupplier))
+    )
 
     def __call__(self, region_name):
         # type: (Union[None, str]) -> BaseClient
@@ -133,4 +130,4 @@ def __call__(self, region_name):
         if region_name in self.denied_regions:
             raise UnknownRegionError("Unable to provide client for region '{}'".format(region_name))
 
-        return self._supplier(region_name)
+        return self._client_supplier(region_name)

test/functional/keyrings/aws_kms/test_client_suppliers.py

@@ -2,7 +2,6 @@
 # SPDX-License-Identifier: Apache-2.0
 """Functional tests for ``aws_encryption_sdk.keyrings.aws_kms.client_suppliers``."""
 import pytest
-from botocore.session import Session
 
 from aws_encryption_sdk.exceptions import UnknownRegionError
 from aws_encryption_sdk.keyrings.aws_kms.client_suppliers import (
@@ -21,36 +20,20 @@ def test_default_supplier_not_implemented():
     with pytest.raises(NotImplementedError) as excinfo:
         test("region")
 
-    excinfo.match("'ClientSupplier' does not implement 'client'")
+    excinfo.match("'ClientSupplier' is not callable")
 
 
 def test_default_supplier_uses_cache():
     supplier = DefaultClientSupplier()
 
     region = "us-west-2"
-    expected = supplier._cache.client(region_name=region, service="kms")
+    expected = supplier._client_cache.client(region_name=region, service="kms")
 
     test = supplier(region)
 
     assert test is expected
 
 
-def test_default_supplier_passes_session():
-    botocore_session = Session()
-
-    test = DefaultClientSupplier(botocore_session=botocore_session)
-
-    assert test._cache._botocore_session is botocore_session
-
-
-def test_allow_regions_supplier_passes_session():
-    botocore_session = Session()
-
-    test = AllowRegionsClientSupplier(allowed_regions=["us-west-2"], botocore_session=botocore_session)
-
-    assert test._supplier._botocore_session is botocore_session
-
-
 @pytest.mark.parametrize(
     "kwargs",
     (
@@ -78,14 +61,6 @@ def test_allow_regions_supplier_denied_not_allowed_region():
     excinfo.match("Unable to provide client for region 'ap-northeast-2'")
 
 
-def test_deny_regions_supplier_passes_session():
-    botocore_session = Session()
-
-    test = DenyRegionsClientSupplier(denied_regions=["us-west-2"], botocore_session=botocore_session)
-
-    assert test._supplier._botocore_session is botocore_session
-
-
 @pytest.mark.parametrize(
     "kwargs",
     (
@@ -111,3 +86,19 @@ def test_deny_regions_supplier_allows_not_denied_region():
     test = DenyRegionsClientSupplier(denied_regions=["us-west-2", "us-east-2"])
 
     assert test("ap-northeast-2")
+
+
+def test_allow_deny_nested_supplier():
+    test_allow = AllowRegionsClientSupplier(
+        allowed_regions=["us-west-2", "us-east-2"], client_supplier=DefaultClientSupplier()
+    )
+    test_deny = DenyRegionsClientSupplier(denied_regions=["us-west-2"], client_supplier=test_allow)
+
+    # test_allow allows us-west-2
+    test_allow("us-west-2")
+
+    # test_deny denies us-west-2 even though its internal supplier (test_allow) allows it
+    with pytest.raises(UnknownRegionError) as excinfo:
+        test_deny("us-west-2")
+
+    excinfo.match("Unable to provide client for region 'us-west-2'")