terraform-modules

name	terraform-modules
description	Design and implement reusable Terraform modules with proper interfaces, testing, and documentation. Use when creating or refactoring infrastructure modules.

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/<module-name>/
  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