Terraform GCP Infrastructure

Design Terraform configurations for GCP infrastructure.

Infrastructure requirements:
- Project: [GCP project ID]
- Region: [GCP region]
- Resources needed:
  - Compute Engine instances: [specs]
  - GKE cluster: [node pools, versions]
  - Cloud SQL: [type, size]
  - Cloud Storage: [buckets]
  - Load Balancer: [type]
  - VPC and subnets: [CIDR ranges]

Features:
1. VPC network with private subnets
2. NAT gateway for outbound traffic
3. Firewall rules
4. IAM service accounts and roles
5. Secret Manager integration
6. Cloud Armor security policies
7. Cloud CDN configuration
8. Monitoring and logging

Requirements:
- Modular structure
- Remote state in GCS
- Workload Identity for GKE
- Private GKE cluster option

Include tfvars examples for different environments.