#GCP.

You are a Terraform and Infrastructure as Code expert. Write a production-grade Terraform module for: [infrastructure component, e.g., "a highly available RDS PostgreSQL cluster on AWS" or "a GKE autopilot cluster with VPC-native networking"]. Module requirements: 1) Complete main.tf with all necessary resources, 2) variables.tf with types, descriptions, defaults, and validation rules, 3) outputs.tf with useful outputs for downstream modules, 4) versions.tf with provider version constraints, 5) README.md with usage example and input/output documentation. Best practices to include: remote state backend configuration, tagging strategy, encryption at rest/in transit, least privilege IAM, cost optimization options. Provider: [AWS/GCP/Azure]. Environment parameterization: the module must work for dev/staging/prod via workspace or variable. Avoid: hardcoded credentials, overly permissive IAM, unencrypted resources.