# Terraform Modules > Design and implement reusable Terraform modules with proper interfaces, testing, and documentation. Use when creating or refactoring infrastructure modules. Use when this capability is needed. - Skill: `tomevault-io/terraform-modules-2` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/terraform-modules-2` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/terraform-modules-2/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: DevOps & Infra - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/terraform-modules-2 --- # Terraform Modules Activate this skill when designing or implementing Terraform modules. ## When to Use - Creating reusable infrastructure components - Refactoring inline resources into modules - Designing module interfaces (variables, outputs) - Testing infrastructure code - Publishing modules to registries ## Module Structure ``` modules// main.tf Primary resource definitions variables.tf Input variables with descriptions and validation outputs.tf Output values for consumers versions.tf Provider and Terraform version constraints README.md Usage documentation with examples examples/ Example configurations tests/ Terratest or terraform test files ``` ## Design Principles - Single responsibility: one module, one concern - Sensible defaults: work out of the box with minimal config - Explicit interfaces: all inputs documented with types and validation - Composable: modules should compose with other modules cleanly - Testable: include examples that can be used as integration tests ## Rules - Pin provider versions in versions.tf - Add validation blocks to variables where appropriate - Use `terraform fmt` before committing - Include at least one working example - Document all variables and outputs - Use data sources over hardcoded values - Never hardcode account IDs, regions, or environment names --- > Source: [ihatesea69/kiro-kit](https://github.com/ihatesea69/kiro-kit) — distributed by [TomeVault](https://tomevault.io).