chore(py-library): update decrypt secrets file

* chore(py-library): update decrypt secrets file

From https://github.com/GoogleCloudPlatform/python-docs-samples/blob/master/scripts/decrypt-secrets.sh

* docs: explain conditional

Co-authored-by: Jeffrey Rennie <rennie@google.com>

Source-Author: Bu Sun Kim <8822365+busunkim96@users.noreply.github.com>
Source-Date: Tue Sep 8 11:35:59 2020 -0600
Source-Repo: googleapis/synthtool
Source-Sha: d302f93d7f47e2852e585ac35ab2d15585717ec0
Source-Link: googleapis/synthtool@d302f93

Author: yoshi-automation

scripts/decrypt-secrets.sh

@@ -20,14 +20,27 @@ ROOT=$( dirname "$DIR" )
 # Work from the project root.
 cd $ROOT
 
+# Prevent it from overriding files.
+# We recommend that sample authors use their own service account files and cloud project.
+# In that case, they are supposed to prepare these files by themselves.
+if [[ -f "testing/test-env.sh" ]] || \
+       [[ -f "testing/service-account.json" ]] || \
+       [[ -f "testing/client-secrets.json" ]]; then
+    echo "One or more target files exist, aborting."
+    exit 1
+fi
+
 # Use SECRET_MANAGER_PROJECT if set, fallback to cloud-devrel-kokoro-resources.
 PROJECT_ID="${SECRET_MANAGER_PROJECT:-cloud-devrel-kokoro-resources}"
 
 gcloud secrets versions access latest --secret="python-docs-samples-test-env" \
+       --project="${PROJECT_ID}" \
        > testing/test-env.sh
 gcloud secrets versions access latest \
        --secret="python-docs-samples-service-account" \
+       --project="${PROJECT_ID}" \
        > testing/service-account.json
 gcloud secrets versions access latest \
        --secret="python-docs-samples-client-secrets" \
-       > testing/client-secrets.json
+       --project="${PROJECT_ID}" \
+       > testing/client-secrets.json

synth.metadata

@@ -19,14 +19,14 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "d91dd8aac77f7a9c5506c238038a26fa4f9e361e"
+        "sha": "d302f93d7f47e2852e585ac35ab2d15585717ec0"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "d91dd8aac77f7a9c5506c238038a26fa4f9e361e"
+        "sha": "d302f93d7f47e2852e585ac35ab2d15585717ec0"
       }
     }
   ],