diff --git a/.github/.OwlBot.lock.yaml b/.github/.OwlBot.lock.yaml
new file mode 100644
index 0000000..c2fc27e
--- /dev/null
+++ b/.github/.OwlBot.lock.yaml
@@ -0,0 +1,18 @@
+# Copyright 2021 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.
+
+docker:
+  image: gcr.io/repo-automation-bots/owlbot-python:latest
+  digest: sha256:c66ba3c8d7bc8566f47df841f98cd0097b28fff0b1864c86f5817f4c8c3e8600
+
diff --git a/.github/.OwlBot.yaml b/.github/.OwlBot.yaml
new file mode 100644
index 0000000..892fbc2
--- /dev/null
+++ b/.github/.OwlBot.yaml
@@ -0,0 +1,18 @@
+# Copyright 2021 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.
+
+docker:
+  image: gcr.io/repo-automation-bots/owlbot-python:latest
+
+begin-after-commit-hash: ee56c3493ec6aeb237ff515ecea949710944a20f
diff --git a/.kokoro/release.sh b/.kokoro/release.sh
index ded1bae..967bc91 100755
--- a/.kokoro/release.sh
+++ b/.kokoro/release.sh
@@ -26,7 +26,7 @@
 export PYTHONUNBUFFERED=1
 
 # Move into the package, build the distribution and upload.
-TWINE_PASSWORD=$(cat "${KOKORO_KEYSTORE_DIR}/73713_google_cloud_pypi_password")
+TWINE_PASSWORD=$(cat "${KOKORO_GFILE_DIR}/secret_manager/google-cloud-pypi-token")
 cd github/google-auth-library-python
 python3 setup.py sdist bdist_wheel
-twine upload --username gcloudpypi --password "${TWINE_PASSWORD}" dist/*
+twine upload --username __token__ --password "${TWINE_PASSWORD}" dist/*
diff --git a/.kokoro/release/common.cfg b/.kokoro/release/common.cfg
index b56ca90..07334fd 100644
--- a/.kokoro/release/common.cfg
+++ b/.kokoro/release/common.cfg
@@ -23,18 +23,8 @@
     value: "github/google-auth-library-python/.kokoro/release.sh"
 }
 
-# Fetch PyPI password	
-before_action {	
-  fetch_keystore {	
-    keystore_resource {	
-      keystore_config_id: 73713	
-      keyname: "google_cloud_pypi_password"	
-    }	
-  }	
-}
-
 # Tokens needed to report release status back to GitHub
 env_vars: {
   key: "SECRET_MANAGER_KEYS"
-  value: "releasetool-publish-reporter-app,releasetool-publish-reporter-googleapis-installation,releasetool-publish-reporter-pem"
-}
\ No newline at end of file
+  value: "releasetool-publish-reporter-app,releasetool-publish-reporter-googleapis-installation,releasetool-publish-reporter-pem,google-cloud-pypi-token"
+}
diff --git a/.kokoro/samples/python3.6/periodic-head.cfg b/.kokoro/samples/python3.6/periodic-head.cfg
new file mode 100644
index 0000000..f9cfcd3
--- /dev/null
+++ b/.kokoro/samples/python3.6/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.7/periodic-head.cfg b/.kokoro/samples/python3.7/periodic-head.cfg
new file mode 100644
index 0000000..f9cfcd3
--- /dev/null
+++ b/.kokoro/samples/python3.7/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.8/periodic-head.cfg b/.kokoro/samples/python3.8/periodic-head.cfg
new file mode 100644
index 0000000..f9cfcd3
--- /dev/null
+++ b/.kokoro/samples/python3.8/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/test-samples-against-head.sh b/.kokoro/test-samples-against-head.sh
new file mode 100755
index 0000000..e974d9d
--- /dev/null
+++ b/.kokoro/test-samples-against-head.sh
@@ -0,0 +1,28 @@
+#!/bin/bash
+# Copyright 2020 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
+#
+#     https://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.
+
+# A customized test runner for samples.
+#
+# For periodic builds, you can specify this file for testing against head.
+
+# `-e` enables the script to automatically fail when a command fails
+# `-o pipefail` sets the exit code to the rightmost comment to exit with a non-zero
+set -eo pipefail
+# Enables `**` to include files nested inside sub-folders
+shopt -s globstar
+
+cd github/google-auth-library-python
+
+exec .kokoro/test-samples-impl.sh
diff --git a/.kokoro/test-samples-impl.sh b/.kokoro/test-samples-impl.sh
new file mode 100755
index 0000000..cf5de74
--- /dev/null
+++ b/.kokoro/test-samples-impl.sh
@@ -0,0 +1,102 @@
+#!/bin/bash
+# Copyright 2021 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
+#
+#     https://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.
+
+
+# `-e` enables the script to automatically fail when a command fails
+# `-o pipefail` sets the exit code to the rightmost comment to exit with a non-zero
+set -eo pipefail
+# Enables `**` to include files nested inside sub-folders
+shopt -s globstar
+
+# Exit early if samples directory doesn't exist
+if [ ! -d "./samples" ]; then
+  echo "No tests run. `./samples` not found"
+  exit 0
+fi
+
+# Disable buffering, so that the logs stream through.
+export PYTHONUNBUFFERED=1
+
+# Debug: show build environment
+env | grep KOKORO
+
+# Install nox
+python3.6 -m pip install --upgrade --quiet nox
+
+# Use secrets acessor service account to get secrets
+if [[ -f "${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" ]]; then
+    gcloud auth activate-service-account \
+	   --key-file="${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" \
+	   --project="cloud-devrel-kokoro-resources"
+fi
+
+# This script will create 3 files:
+# - testing/test-env.sh
+# - testing/service-account.json
+# - testing/client-secrets.json
+./scripts/decrypt-secrets.sh
+
+source ./testing/test-env.sh
+export GOOGLE_APPLICATION_CREDENTIALS=$(pwd)/testing/service-account.json
+
+# For cloud-run session, we activate the service account for gcloud sdk.
+gcloud auth activate-service-account \
+       --key-file "${GOOGLE_APPLICATION_CREDENTIALS}"
+
+export GOOGLE_CLIENT_SECRETS=$(pwd)/testing/client-secrets.json
+
+echo -e "\n******************** TESTING PROJECTS ********************"
+
+# Switch to 'fail at end' to allow all tests to complete before exiting.
+set +e
+# Use RTN to return a non-zero value if the test fails.
+RTN=0
+ROOT=$(pwd)
+# Find all requirements.txt in the samples directory (may break on whitespace).
+for file in samples/**/requirements.txt; do
+    cd "$ROOT"
+    # Navigate to the project folder.
+    file=$(dirname "$file")
+    cd "$file"
+
+    echo "------------------------------------------------------------"
+    echo "- testing $file"
+    echo "------------------------------------------------------------"
+
+    # Use nox to execute the tests for the project.
+    python3.6 -m nox -s "$RUN_TESTS_SESSION"
+    EXIT=$?
+
+    # If this is a periodic build, send the test log to the FlakyBot.
+    # See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
+    if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
+      chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
+      $KOKORO_GFILE_DIR/linux_amd64/flakybot
+    fi
+
+    if [[ $EXIT -ne 0 ]]; then
+      RTN=1
+      echo -e "\n Testing failed: Nox returned a non-zero exit code. \n"
+    else
+      echo -e "\n Testing completed.\n"
+    fi
+
+done
+cd "$ROOT"
+
+# Workaround for Kokoro permissions issue: delete secrets
+rm testing/{test-env.sh,client-secrets.json,service-account.json}
+
+exit "$RTN"
diff --git a/.kokoro/test-samples.sh b/.kokoro/test-samples.sh
index dbfe9fb..6cea6d4 100755
--- a/.kokoro/test-samples.sh
+++ b/.kokoro/test-samples.sh
@@ -13,6 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# The default test runner for samples.
+#
+# For periodic builds, we rewinds the repo to the latest release, and
+# run test-samples-impl.sh.
 
 # `-e` enables the script to automatically fail when a command fails
 # `-o pipefail` sets the exit code to the rightmost comment to exit with a non-zero
@@ -24,87 +28,19 @@
 
 # Run periodic samples tests at latest release
 if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
+    # preserving the test runner implementation.
+    cp .kokoro/test-samples-impl.sh "${TMPDIR}/test-samples-impl.sh"
+    echo "--- IMPORTANT IMPORTANT IMPORTANT ---"
+    echo "Now we rewind the repo back to the latest release..."
     LATEST_RELEASE=$(git describe --abbrev=0 --tags)
     git checkout $LATEST_RELEASE
-fi
-
-# Exit early if samples directory doesn't exist
-if [ ! -d "./samples" ]; then
-  echo "No tests run. `./samples` not found"
-  exit 0
-fi
-
-# Disable buffering, so that the logs stream through.
-export PYTHONUNBUFFERED=1
-
-# Debug: show build environment
-env | grep KOKORO
-
-# Install nox
-python3.6 -m pip install --upgrade --quiet nox
-
-# Use secrets acessor service account to get secrets
-if [[ -f "${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" ]]; then
-    gcloud auth activate-service-account \
-	   --key-file="${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" \
-	   --project="cloud-devrel-kokoro-resources"
-fi
-
-# This script will create 3 files:
-# - testing/test-env.sh
-# - testing/service-account.json
-# - testing/client-secrets.json
-./scripts/decrypt-secrets.sh
-
-source ./testing/test-env.sh
-export GOOGLE_APPLICATION_CREDENTIALS=$(pwd)/testing/service-account.json
-
-# For cloud-run session, we activate the service account for gcloud sdk.
-gcloud auth activate-service-account \
-       --key-file "${GOOGLE_APPLICATION_CREDENTIALS}"
-
-export GOOGLE_CLIENT_SECRETS=$(pwd)/testing/client-secrets.json
-
-echo -e "\n******************** TESTING PROJECTS ********************"
-
-# Switch to 'fail at end' to allow all tests to complete before exiting.
-set +e
-# Use RTN to return a non-zero value if the test fails.
-RTN=0
-ROOT=$(pwd)
-# Find all requirements.txt in the samples directory (may break on whitespace).
-for file in samples/**/requirements.txt; do
-    cd "$ROOT"
-    # Navigate to the project folder.
-    file=$(dirname "$file")
-    cd "$file"
-
-    echo "------------------------------------------------------------"
-    echo "- testing $file"
-    echo "------------------------------------------------------------"
-
-    # Use nox to execute the tests for the project.
-    python3.6 -m nox -s "$RUN_TESTS_SESSION"
-    EXIT=$?
-
-    # If this is a periodic build, send the test log to the FlakyBot.
-    # See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
-    if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
-      chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
-      $KOKORO_GFILE_DIR/linux_amd64/flakybot
+    echo "The current head is: "
+    echo $(git rev-parse --verify HEAD)
+    echo "--- IMPORTANT IMPORTANT IMPORTANT ---"
+    # move back the test runner implementation if there's no file.
+    if [ ! -f .kokoro/test-samples-impl.sh ]; then
+	cp "${TMPDIR}/test-samples-impl.sh" .kokoro/test-samples-impl.sh
     fi
+fi
 
-    if [[ $EXIT -ne 0 ]]; then
-      RTN=1
-      echo -e "\n Testing failed: Nox returned a non-zero exit code. \n"
-    else
-      echo -e "\n Testing completed.\n"
-    fi
-
-done
-cd "$ROOT"
-
-# Workaround for Kokoro permissions issue: delete secrets
-rm testing/{test-env.sh,client-secrets.json,service-account.json}
-
-exit "$RTN"
+exec .kokoro/test-samples-impl.sh
diff --git a/synth.py b/owlbot.py
similarity index 100%
rename from synth.py
rename to owlbot.py
diff --git a/synth.metadata b/synth.metadata
deleted file mode 100644
index 0de642b..0000000
--- a/synth.metadata
+++ /dev/null
@@ -1,54 +0,0 @@
-{
-  "sources": [
-    {
-      "git": {
-        "name": ".",
-        "remote": "https://github.com/googleapis/google-auth-library-python.git",
-        "sha": "f062da8392c32fb3306cdc6e4dbae78212aa0dc7"
-      }
-    },
-    {
-      "git": {
-        "name": "synthtool",
-        "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "16ec872dd898d7de6e1822badfac32484b5d9031"
-      }
-    }
-  ],
-  "generatedFiles": [
-    ".kokoro/build.sh",
-    ".kokoro/continuous/common.cfg",
-    ".kokoro/continuous/continuous.cfg",
-    ".kokoro/docker/docs/Dockerfile",
-    ".kokoro/docker/docs/fetch_gpg_keys.sh",
-    ".kokoro/docs/common.cfg",
-    ".kokoro/docs/docs-presubmit.cfg",
-    ".kokoro/docs/docs.cfg",
-    ".kokoro/populate-secrets.sh",
-    ".kokoro/presubmit/common.cfg",
-    ".kokoro/presubmit/presubmit.cfg",
-    ".kokoro/publish-docs.sh",
-    ".kokoro/release.sh",
-    ".kokoro/release/common.cfg",
-    ".kokoro/release/release.cfg",
-    ".kokoro/samples/lint/common.cfg",
-    ".kokoro/samples/lint/continuous.cfg",
-    ".kokoro/samples/lint/periodic.cfg",
-    ".kokoro/samples/lint/presubmit.cfg",
-    ".kokoro/samples/python3.6/common.cfg",
-    ".kokoro/samples/python3.6/continuous.cfg",
-    ".kokoro/samples/python3.6/periodic.cfg",
-    ".kokoro/samples/python3.6/presubmit.cfg",
-    ".kokoro/samples/python3.7/common.cfg",
-    ".kokoro/samples/python3.7/continuous.cfg",
-    ".kokoro/samples/python3.7/periodic.cfg",
-    ".kokoro/samples/python3.7/presubmit.cfg",
-    ".kokoro/samples/python3.8/common.cfg",
-    ".kokoro/samples/python3.8/continuous.cfg",
-    ".kokoro/samples/python3.8/periodic.cfg",
-    ".kokoro/samples/python3.8/presubmit.cfg",
-    ".kokoro/test-samples.sh",
-    ".kokoro/trampoline.sh",
-    ".kokoro/trampoline_v2.sh"
-  ]
-}
\ No newline at end of file