feat: provide and use Python version support check (#832)

Author: vchudnov-g

google/api_core/__init__.py

@@ -17,6 +17,24 @@
 This package contains common code and utilities used by Google client libraries.
 """
 
+from google.api_core import _python_package_support
+from google.api_core import _python_version_support
 from google.api_core import version as api_core_version
 
 __version__ = api_core_version.__version__
+
+# NOTE: Until dependent artifacts require this version of
+# google.api_core, the functionality below must be made available
+# manually in those artifacts.
+
+# expose dependency checks for external callers
+check_python_version = _python_version_support.check_python_version
+check_dependency_versions = _python_package_support.check_dependency_versions
+warn_deprecation_for_versions_less_than = (
+    _python_package_support.warn_deprecation_for_versions_less_than
+)
+DependencyConstraint = _python_package_support.DependencyConstraint
+
+# perform version checks against api_core, and emit warnings if needed
+check_python_version(package="google.api_core")
+check_dependency_versions("google.api_core")

google/api_core/_python_package_support.py

@@ -0,0 +1,209 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License 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.
+
+"""Code to check versions of dependencies used by Google Cloud Client Libraries."""
+
+import warnings
+import sys
+from typing import Optional
+
+from collections import namedtuple
+
+from ._python_version_support import (
+    _flatten_message,
+    _get_distribution_and_import_packages,
+)
+
+from packaging.version import parse as parse_version
+
+# Here we list all the packages for which we want to issue warnings
+# about deprecated and unsupported versions.
+DependencyConstraint = namedtuple(
+    "DependencyConstraint",
+    ["package_name", "minimum_fully_supported_version", "recommended_version"],
+)
+_PACKAGE_DEPENDENCY_WARNINGS = [
+    DependencyConstraint(
+        "google.protobuf",
+        minimum_fully_supported_version="4.25.8",
+        recommended_version="6.x",
+    )
+]
+
+
+DependencyVersion = namedtuple("DependencyVersion", ["version", "version_string"])
+# Version string we provide in a DependencyVersion when we can't determine the version of a
+# package.
+UNKNOWN_VERSION_STRING = "--"
+
+
+def get_dependency_version(
+    dependency_name: str,
+) -> DependencyVersion:
+    """Get the parsed version of an installed package dependency.
+
+    This function checks for an installed package and returns its version
+    as a `packaging.version.Version` object for safe comparison. It handles
+    both modern (Python 3.8+) and legacy (Python 3.7) environments.
+
+    Args:
+        dependency_name: The distribution name of the package (e.g., 'requests').
+
+    Returns:
+        A DependencyVersion namedtuple with `version` and
+        `version_string` attributes, or `DependencyVersion(None,
+        UNKNOWN_VERSION_STRING)` if the package is not found or
+        another error occurs during version discovery.
+
+    """
+    try:
+        if sys.version_info >= (3, 8):
+            from importlib import metadata
+
+            version_string = metadata.version(dependency_name)
+            return DependencyVersion(parse_version(version_string), version_string)
+
+        # TODO(https://github.com/googleapis/python-api-core/issues/835): Remove
+        # this code path once we drop support for Python 3.7
+        else:  # pragma: NO COVER
+            # Use pkg_resources, which is part of setuptools.
+            import pkg_resources
+
+            version_string = pkg_resources.get_distribution(dependency_name).version
+            return DependencyVersion(parse_version(version_string), version_string)
+
+    except Exception:
+        return DependencyVersion(None, UNKNOWN_VERSION_STRING)
+
+
+def warn_deprecation_for_versions_less_than(
+    consumer_import_package: str,
+    dependency_import_package: str,
+    minimum_fully_supported_version: str,
+    recommended_version: Optional[str] = None,
+    message_template: Optional[str] = None,
+):
+    """Issue any needed deprecation warnings for `dependency_import_package`.
+
+    If `dependency_import_package` is installed at a version less than
+    `minimum_fully_supported_version`, this issues a warning using either a
+    default `message_template` or one provided by the user. The
+    default `message_template` informs the user that they will not receive
+    future updates for `consumer_import_package` if
+    `dependency_import_package` is somehow pinned to a version lower
+    than `minimum_fully_supported_version`.
+
+    Args:
+      consumer_import_package: The import name of the package that
+        needs `dependency_import_package`.
+      dependency_import_package: The import name of the dependency to check.
+      minimum_fully_supported_version: The dependency_import_package version number
+        below which a deprecation warning will be logged.
+      recommended_version: If provided, the recommended next version, which
+        could be higher than `minimum_fully_supported_version`.
+      message_template: A custom default message template to replace
+        the default. This `message_template` is treated as an
+        f-string, where the following variables are defined:
+        `dependency_import_package`, `consumer_import_package` and
+        `dependency_distribution_package` and
+        `consumer_distribution_package` and `dependency_package`,
+        `consumer_package` , which contain the import packages, the
+        distribution packages, and pretty string with both the
+        distribution and import packages for the dependency and the
+        consumer, respectively; and `minimum_fully_supported_version`,
+        `version_used`, and `version_used_string`, which refer to supported
+        and currently-used versions of the dependency.
+
+    """
+    if (
+        not consumer_import_package
+        or not dependency_import_package
+        or not minimum_fully_supported_version
+    ):  # pragma: NO COVER
+        return
+    dependency_version = get_dependency_version(dependency_import_package)
+    if not dependency_version.version:
+        return
+    if dependency_version.version < parse_version(minimum_fully_supported_version):
+        (
+            dependency_package,
+            dependency_distribution_package,
+        ) = _get_distribution_and_import_packages(dependency_import_package)
+        (
+            consumer_package,
+            consumer_distribution_package,
+        ) = _get_distribution_and_import_packages(consumer_import_package)
+
+        recommendation = (
+            " (we recommend {recommended_version})" if recommended_version else ""
+        )
+        message_template = message_template or _flatten_message(
+            """
+            DEPRECATION: Package {consumer_package} depends on
+            {dependency_package}, currently installed at version
+            {version_used_string}. Future updates to
+            {consumer_package} will require {dependency_package} at
+            version {minimum_fully_supported_version} or
+            higher{recommendation}. Please ensure that either (a) your
+            Python environment doesn't pin the version of
+            {dependency_package}, so that updates to
+            {consumer_package} can require the higher version, or (b)
+            you manually update your Python environment to use at
+            least version {minimum_fully_supported_version} of
+            {dependency_package}.
+            """
+        )
+        warnings.warn(
+            message_template.format(
+                consumer_import_package=consumer_import_package,
+                dependency_import_package=dependency_import_package,
+                consumer_distribution_package=consumer_distribution_package,
+                dependency_distribution_package=dependency_distribution_package,
+                dependency_package=dependency_package,
+                consumer_package=consumer_package,
+                minimum_fully_supported_version=minimum_fully_supported_version,
+                recommendation=recommendation,
+                version_used=dependency_version.version,
+                version_used_string=dependency_version.version_string,
+            ),
+            FutureWarning,
+        )
+
+
+def check_dependency_versions(
+    consumer_import_package: str, *package_dependency_warnings: DependencyConstraint
+):
+    """Bundle checks for all package dependencies.
+
+    This function can be called by all consumers of google.api_core,
+    to emit needed deprecation warnings for any of their
+    dependencies. The dependencies to check can be passed as arguments, or if
+    none are provided, it will default to the list in
+    `_PACKAGE_DEPENDENCY_WARNINGS`.
+
+    Args:
+      consumer_import_package: The distribution name of the calling package, whose
+        dependencies we're checking.
+      *package_dependency_warnings: A variable number of DependencyConstraint
+        objects, each specifying a dependency to check.
+    """
+    if not package_dependency_warnings:
+        package_dependency_warnings = tuple(_PACKAGE_DEPENDENCY_WARNINGS)
+    for package_info in package_dependency_warnings:
+        warn_deprecation_for_versions_less_than(
+            consumer_import_package,
+            package_info.package_name,
+            package_info.minimum_fully_supported_version,
+            recommended_version=package_info.recommended_version,
+        )