GCP Shared VPC with Multiple Projects

Terraform configuration for setting up Google Cloud Shared VPC with separate production and development service projects.

What This Creates

• Host Project: Contains the shared VPC network
• Production Service Project: For production workloads
• Development Service Project: For development workloads
• Cloud Interconnect: Partner attachments for on-premises connectivity

Architecture Design

Prerequisites

1. Google Cloud account with billing enabled
2. Organization admin permissions
3. Terraform >= 1.0 installed
4. gcloud CLI installed

Quick Start

1. Clone Repository

git clone <repository-url>
cd gcp-sharedvpc-with-multiple-projects

2. Get Required Information

# Find your organization ID
gcloud organizations list

# Find your billing account
gcloud billing accounts list

3. Create terraform.tfvars

host_project_id         = "my-shared-vpc-host"
prod_service_project_id = "my-prod-service"
dev_service_project_id  = "my-dev-service"
organization_id         = "123456789012"
billing_account         = "ABCDEF-123456-ABCDEF"
default_region          = "us-central1"
secondary_region        = "us-east1"

4. Deploy

# Initialize Terraform
terraform init

# Review the plan
terraform plan

# Apply the configuration
terraform apply

Network Configuration

Environment	Subnet	Primary CIDR	Pods Range	Services Range
Production	prod-subnet-01	10.1.0.0/24	10.10.0.0/16	10.20.0.0/16
Production	prod-subnet-02	10.2.0.0/24	10.11.0.0/16	10.21.0.0/16
Development	dev-subnet-01	10.3.0.0/24	10.30.0.0/16	10.40.0.0/16
Development	dev-subnet-02	10.4.0.0/24	10.31.0.0/16	10.41.0.0/16

Files

• main.tf - Main infrastructure resources
• variables.tf - Input variables
• outputs.tf - Output values
• iam.tf - IAM permissions
• providers.tf - Provider configuration

Common Commands

# Check deployment status
terraform output

# Verify shared VPC
gcloud compute shared-vpc list-associated-projects <host-project-id>

# List subnets
gcloud compute networks subnets list --project=<host-project-id>

# Destroy everything
terraform destroy

Troubleshooting

Permission Issues: Ensure you have Organization Admin or Project Creator + Billing Account User roles.

API Errors: APIs are automatically enabled, but check if billing is active.

Project ID Conflicts: All project IDs must be globally unique in GCP.

Clean Up

terraform destroy

Warning: This will delete all projects and resources. Make sure you have backups of any important data.

Support

For issues, check the official GCP documentation or Terraform Google Provider docs.