A comprehensive startup script template that installs Vault on a fresh GCE instance, configures systemd service, pulls and decrypts TLS certificates from GCS/KMS, sets up logging agents (Stackdriver/fluentd), enables auto-unseal, and applies security hardening (core dumps disabled, no swap, unprivileged user). It is well-structured, idempotent (checks for completion marker), and includes thoughtful details like using Python's zipfile to avoid installing unzip, setting capabilities for mlock, and handling proxy environments. Although tied to module variables, the script demonstrates a robust pattern for bootstrapping stateful services on ephemeral VMs that could be adapted for other use cases.

A shared RSpec example block for integration testing Google Managed Instance Groups. It systematically waits for the group to become stable, checks instance health states, and captures serial console output to verify successful startup script execution. The code uses defensive loops with timeouts, parses gcloud JSON output, and provides clear assertions. This is a reusable test pattern for any GCP module that deploys instance groups, demonstrating good testing practices for infrastructure.

Manages the lifecycle of self-signed TLS certificates for Vault. It generates a root CA and server certificate, encrypts the server private key with Google Cloud KMS via `google_kms_secret_ciphertext`, and stores the encrypted key and certificates in GCS. It cleverly uses `count` based on `manage_tls` variable to conditionally enable or bypass TLS generation, and marks the encrypted key object with `ignore_changes` to prevent perpetual diffs. This is a clean pattern for handling secrets in Terraform without exposing private keys in state.