feat(compatability): Check Python Runtime (#372)

Issues a WARNING if the Python Version will become/is unsupported.
Will start issuing WARNING for Python Version less than 3.6.

Author: texastony

src/aws_encryption_sdk/__init__.py

@@ -12,13 +12,13 @@
 # language governing permissions and limitations under the License.
 """High level AWS Encryption SDK client functions."""
 # Below are imported for ease of use by implementors
-
 import warnings
 
 import attr
 
 from aws_encryption_sdk.caches.local import LocalCryptoMaterialsCache  # noqa
 from aws_encryption_sdk.caches.null import NullCryptoMaterialsCache  # noqa
+from aws_encryption_sdk.compatability import _warn_deprecated_python
 from aws_encryption_sdk.exceptions import AWSEncryptionSDKClientError  # noqa
 from aws_encryption_sdk.identifiers import Algorithm, CommitmentPolicy, __version__  # noqa
 from aws_encryption_sdk.internal.utils.signature import SignaturePolicy  # noqa
@@ -36,6 +36,8 @@
     StreamEncryptor,
 )
 
+_warn_deprecated_python()
+
 
 @attr.s(hash=True)
 class EncryptionSDKClientConfig(object):

src/aws_encryption_sdk/compatability.py

@@ -0,0 +1,39 @@
+# Copyright 2017 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.
+"""Contains logic for checking ESDK and Python Version"""
+import sys
+import warnings
+
+DEPRECATION_DATE_MAP = {"1.x": "2022-06-30", "2.x": "2022-07-01"}
+
+
+def _warn_deprecated_python():
+    """Template for deprecation of Python warning."""
+    deprecated_versions = {
+        (2, 7): {"date": DEPRECATION_DATE_MAP["2.x"]},
+        (3, 4): {"date": DEPRECATION_DATE_MAP["2.x"]},
+        (3, 5): {"date": "2021-11-10"},
+    }
+    py_version = (sys.version_info.major, sys.version_info.minor)
+    minimum_version = (3, 6)
+
+    if py_version in deprecated_versions:
+        params = deprecated_versions[py_version]
+        warning = (
+            "aws-encryption-sdk will no longer support Python {}.{} "
+            "starting {}. To continue receiving service updates, "
+            "bug fixes, and security updates please upgrade to Python {}.{} or "
+            "later. For more information, see SUPPORT_POLICY.rst: "
+            "https://github.com/aws/aws-encryption-sdk-python/blob/master/SUPPORT_POLICY.rst"
+        ).format(py_version[0], py_version[1], minimum_version[0], minimum_version[1], params["date"])
+        warnings.warn(warning, DeprecationWarning)

src/aws_encryption_sdk/streaming_client.py

@@ -70,7 +70,7 @@
 _LOGGER = logging.getLogger(__name__)
 
 
-@attr.s(hash=True)
+@attr.s(hash=True)  # pylint: disable=too-many-instance-attributes
 @six.add_metaclass(abc.ABCMeta)
 class _ClientConfig(object):  # pylint: disable=too-many-instance-attributes
     """Parent configuration object for StreamEncryptor and StreamDecryptor objects.

test/pylintrc

@@ -5,6 +5,7 @@ disable =
     missing-docstring,  # we don't write docstrings for tests
     bad-continuation,  # we let black handle this
     ungrouped-imports,  # we let isort handle this
+    wrong-import-order,  # we let isort handle this
     abstract-class-instantiated,  # we do this on purpose to test that they are enforced
     no-member,  # raised on patched objects with mock checks
     no-self-use,  # common pattern when using pytest classes: can be enabled once all tests are refactored to pytest functions
@@ -24,6 +25,7 @@ disable =
     super-with-arguments,
     consider-using-f-string # disable until 2022-05-05; 6 months after 3.5 deprecation
 
+
 [VARIABLES]
 additional-builtins = raw_input
 

test/unit/test_compatability.py

@@ -0,0 +1,38 @@
+# Copyright 2017 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.
+"""Unit test suite for aws_encryption_sdk.compatability"""
+import sys
+
+import mock
+import pytest
+
+from aws_encryption_sdk.compatability import _warn_deprecated_python
+
+pytestmark = [pytest.mark.unit, pytest.mark.local]
+
+
+class TestWarnDeprecatedPython:
+    def test_happy_version(self):
+        with mock.patch.object(sys, "version_info") as v_info:
+            v_info.major = 3
+            v_info.minor = 6
+            with pytest.warns(None) as record:
+                _warn_deprecated_python()
+            assert len(record) == 0
+
+    def test_below_warn(self):
+        with mock.patch.object(sys, "version_info") as v_info:
+            v_info.major = 2
+            v_info.minor = 7
+            with pytest.warns(DeprecationWarning):
+                _warn_deprecated_python()