@@ -1,3 +1,5 @@
 # Composer Tools
 
 * [Composer DAGs Pausing/Unpausing script](composer_dags.md)
+* [google-api-core Python 3.11 Deprecation Workaround](google_api_core_workaround/README.md)
+
@@ -0,0 +1,86 @@
+# Workaround for google-api-core Python 3.11 Deprecation Warning
+
+This tool provides a workaround for Cloud Composer environments running Python 3.11 where `google-api-core` triggers high DAG parsing times, elevated worker CPU usage, or deprecation log spam.
+
+## When to Use This
+
+Use this workaround if:
+- Your Cloud Composer environment is running on Python 3.11.
+- You see `FutureWarning` logs from `google.api_core._python_version_support` indicating that Python 3.11 will reach end of life.
+- You notice increased DAG parsing latency or worker CPU usage after entering the 365-day Python 3.11 EOL window (October 2026).
+
+### Root Cause
+`google-api-core` emits a deprecation warning starting 365 days before a Python version reaches community EOL. While emitting this warning, it calls `importlib.metadata.packages_distributions()`, which scans all installed packages across `site-packages` on disk. In Cloud Composer, where DAG processors and workers frequently spawn fresh Python subprocesses, repeated filesystem metadata scans cause measurable parse latency and CPU overhead.
+
+## What the Workaround Does
+
+`sitecustomize.py` is an import hook that CPython runs automatically on startup before user code executes. This script:
+1. Changes `DEPRECATION_WARNING_PERIOD` from 365 days to 60 days, deferring the warning until August 2027.
+2. Stubs `_get_pypi_package_name` to return `None`, preventing `packages_distributions()` from scanning disk.
+3. Cleans up its own folder from `sys.path` immediately after load so subsequent imports do not re-scan the patch directory.
+
+Because the file contains no DAG objects and avoids DAG-related keywords, Airflow's default `dag_discovery_safe_mode = True` ignores it during DAG parsing.
+
+## How to Apply
+
+### Step 1: Upload `sitecustomize.py` to GCS
+
+Copy `sitecustomize.py` to a `patches/` directory in your environment's DAGs bucket:
+
+```bash
+gcloud storage cp sitecustomize.py gs://<YOUR_DAGS_BUCKET>/dags/patches/sitecustomize.py
+```
+
+You can find your DAGs bucket name by running:
+```bash
+gcloud composer environments describe <ENVIRONMENT_NAME> \
+    --location <LOCATION> \
+    --format="value(config.dagGcsPrefix)"
+```
+
+### Step 2: Set the `PYTHONPATH` Environment Variable
+
+Add the patch folder to `PYTHONPATH` on your Composer environment:
+
+```bash
+gcloud composer environments update <ENVIRONMENT_NAME> \
+    --location <LOCATION> \
+    --update-env-variables PYTHONPATH=/home/airflow/gcs/dags/patches
+```
+
+> **Important:** If your environment already defines a custom `PYTHONPATH`, preserve your existing paths by separating them with a colon (`:`):
+> ```bash
+> --update-env-variables PYTHONPATH=/home/airflow/gcs/dags/patches:<EXISTING_PATH>
+> ```
+
+This update triggers a rolling restart of Composer workloads. Once restarted, all Python subprocesses (scheduler, workers, DAG processor) will load `sitecustomize.py` on startup.
+
+### Note on `dag_discovery_safe_mode`
+
+If you explicitly disabled safe mode (`[core] dag_discovery_safe_mode = False`), add `patches/*` to your `dags/.airflowignore` file to prevent the DAG file processor from attempting to parse the patch directory:
+
+```text
+patches/*
+```
+
+## Verification
+
+After the environment finishes updating:
+1. Check Cloud Logging or task logs in the Airflow UI. The `_python_version_support` `FutureWarning` messages should stop appearing.
+2. In the Cloud Monitoring dashboard for Composer, check the **DAG Processing: Total Parse Time** metric. Parse times should return to baseline levels.
+
+## How to Remove
+
+Once your environment is upgraded to a Composer image or `google-api-core` version with the upstream fix, remove the workaround:
+
+1. Remove `PYTHONPATH` (or restore your original value):
+   ```bash
+   gcloud composer environments update <ENVIRONMENT_NAME> \
+       --location <LOCATION> \
+       --remove-env-variables PYTHONPATH
+   ```
+
+2. Delete the patch file from the bucket:
+   ```bash
+   gcloud storage rm gs://<YOUR_DAGS_BUCKET>/dags/patches/sitecustomize.py
+   ```
@@ -0,0 +1,91 @@
+# Copyright 2026 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.
+
+"""CPython sitecustomize hook for patching google.api_core deprecation check."""
+
+import datetime
+import importlib.util
+import os
+import sys
+
+# Remove this patch directory from sys.path to avoid redundant lookups
+# on subsequent module imports when loaded via PYTHONPATH.
+_patch_file = globals().get("__file__")
+if _patch_file:
+    _patch_dir = os.path.abspath(os.path.dirname(_patch_file))
+    _is_site_dir = any(
+        part in ("site-packages", "dist-packages")
+        for part in _patch_dir.split(os.sep)
+    )
+    if not _is_site_dir:
+        _patch_dir_slash = _patch_dir + os.sep
+        sys.path[:] = [
+            p
+            for p in sys.path
+            if not isinstance(p, (str, os.PathLike))
+            or not os.path.isabs(p)
+            or (
+                os.path.abspath(p) != _patch_dir
+                and os.path.abspath(p) != _patch_dir_slash
+            )
+        ]
+        sys.path_importer_cache.pop(_patch_dir, None)
+        sys.path_importer_cache.pop(_patch_dir_slash, None)
+
+TARGET_MODULE = "google.api_core._python_version_support"
+
+
+class _GoogleApiCorePatcher:
+    """Import hook to patch DEPRECATION_WARNING_PERIOD on load."""
+
+    def find_spec(self, fullname, path=None, target=None):
+        if fullname == TARGET_MODULE:
+            try:
+                sys.meta_path.remove(self)
+            except ValueError:
+                pass
+
+            try:
+                spec = importlib.util.find_spec(fullname)
+            except Exception:
+                return None
+
+            if spec and spec.loader:
+                orig_exec_module = spec.loader.exec_module
+
+                def exec_module(module):
+                    import importlib.metadata
+
+                    orig_packages_distributions = getattr(
+                        importlib.metadata, "packages_distributions", None
+                    )
+                    if orig_packages_distributions:
+                        importlib.metadata.packages_distributions = lambda: {}
+                    try:
+                        orig_exec_module(module)
+                    finally:
+                        if orig_packages_distributions:
+                            importlib.metadata.packages_distributions = (
+                                orig_packages_distributions
+                            )
+                    module.DEPRECATION_WARNING_PERIOD = datetime.timedelta(days=60)
+                    module._get_pypi_package_name = lambda module_name: None
+
+                spec.loader.exec_module = exec_module
+            return spec
+        return None
+
+
+if not any(type(h).__name__ == "_GoogleApiCorePatcher" for h in sys.meta_path):
+    sys.meta_path.insert(0, _GoogleApiCorePatcher())