terraform-module - SKILL.md Agent Skill

name: terraform-module description: Scaffold a new Terraform module with the canonical file layout — terraform.tf, main.tf, variables.tf, outputs.tf, README.md — and house style. Use when creating a new Terraform module, adding a module under a modules/ directory, or restructuring an existing module to the standard layout. license: MIT

Scaffold a Terraform module

Creates a module with the canonical five-file layout. Apply the terraform-style skill's conventions while filling in real content, and finish with the terraform-validate workflow.

1. Name the module and pick providers

Directory: kebab-case, named for what the module manages (modules/ecr-registry, not modules/registry-stuff). One cohesive concern per module.
Decide which providers the module needs and their major-version constraints before writing resources — they go in terraform.tf on day one.

2. Create the five canonical files

Copy the skeletons from this skill's templates/ directory into the new module directory and replace the placeholder content:

File	Template shows
`terraform.tf`	`required_version` + `required_providers` with major-version pins
`main.tf`	a primary resource named `main`, plus naming-convention reminders
`variables.tf`	a required flat variable, an object variable with `optional()` defaults
`outputs.tf`	flat primary-attribute outputs and one grouped object output
`README.md`	title, purpose paragraph, Usage example, Inputs/Outputs tables

Every variable and output keeps a description — the linter enforces this.

3. Apply the house style

While implementing, follow the terraform-style skill. The rules that most often shape a new module's interface:

set(string) for unordered unique inputs; primary resource named main;
name_prefix (trailing -) for account-unique named resources;
boolean-gated resources via for_each = toset(var.x ? ["true"] : []);
outputs named for the attribute, cohesive facets grouped into one object;
optional strings default to null, never "".

Split cohesive resource families into domain files (iam-node.tf, signing.tf) once main.tf grows past a screenful — the five canonical files are the floor, not the ceiling.

4. Document and validate

Fill in the README's Usage example with a realistic call (module "x" { source = "../..." }) showing only the inputs a typical caller sets.
Run the terraform-validate workflow (fmt → init/validate → tflint) on the new module before committing.