terraform-module-library

Structure the module with main.tf for resources, variables.tf for inputs with validation blocks, outputs.tf for exported attributes, and versions.tf for provider pinning. Add an examples/ directory showing complete usage and tests/ with Terratest files to verify the module works.

A standard module contains main.tf, variables.tf, outputs.tf, versions.tf, a README.md, an examples/ directory with a complete usage example, and a tests/ directory. This layout makes modules composable, documented, and testable across teams.

Write a Go test using the terratest terraform package that points TerraformDir at your examples/complete directory, then run InitAndApply and assert on outputs like vpc_id. Always defer terraform.Destroy to clean up resources after the test finishes.

The module structure and best practices are consistent across providers, but resources are provider-specific. This Skill organizes modules per cloud (aws/, azure/, gcp/) with equivalent patterns like VPC/VNet, EKS/AKS/GKE, and RDS/Cloud SQL.

Use validation blocks inside variable definitions with condition expressions and error_message strings. For example, a CIDR block variable can be checked with a regex to ensure valid IPv4 CIDR notation before any resources are created.