ci: add terraform-docs workflow (#27)

* ci: add `terraform-docs` workflow

* terraform-docs: automated action

* ci: tweak `terraform-docs` commit message

* ci: add paths filter

* ci: fixup job names

* chore: update `git-commit-message`

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

.github/workflows/terraform-docs.yaml

@@ -0,0 +1,21 @@
+name: Terraform docs
+
+on:
+  pull_request:
+    paths:
+      - "infra/terraform/modules/**"
+
+jobs:
+  generate-terraform-docs:
+    name: Generate
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.ref }}
+
+      - uses: terraform-docs/gh-actions@main
+        with:
+          find-dir: "infra/terraform/modules"
+          git-commit-message: "docs: update Terraform docs"
+          git-push: true

.lintstagedrc.mjs

@@ -0,0 +1,27 @@
+import chalk from "chalk";
+import path from "path";
+import { execSync } from "child_process";
+
+const generateTerraformDocs = (filenames) => {
+  try {
+    execSync("terraform-docs --version", { stdio: "ignore" });
+  } catch (error) {
+    const message = `Warning: \`terraform-docs\` is not installed so cannot update Terraform module docs. Please install \`terraform-docs\`, see https://github.com/terraform-docs/terraform-docs/#installation.`;
+
+    console.warn(chalk.yellow(message));
+    return [];
+  }
+
+  const modules = [...new Set(filenames.map((filename) => path.dirname(filename)))];
+
+  return [
+    ...modules.map((module) => `terraform-docs markdown --output-file ${module}/README.md ${module}`),
+    "git add terraform/modules/**/README.md",
+  ];
+};
+
+export default {
+  "*": ["prettier --ignore-unknown --write"],
+  "*.{tf,tfvars}": ["terraform fmt"],
+  "terraform/modules/**/*": generateTerraformDocs,
+};

infra/terraform/modules/account/README.md

@@ -0,0 +1,25 @@
+<!-- BEGIN_TF_DOCS -->
+## Requirements
+
+No requirements.
+
+## Providers
+
+No providers.
+
+## Modules
+
+No modules.
+
+## Resources
+
+No resources.
+
+## Inputs
+
+No inputs.
+
+## Outputs
+
+No outputs.
+<!-- END_TF_DOCS -->

infra/terraform/modules/service/README.md

@@ -0,0 +1,25 @@
+<!-- BEGIN_TF_DOCS -->
+## Requirements
+
+No requirements.
+
+## Providers
+
+No providers.
+
+## Modules
+
+No modules.
+
+## Resources
+
+No resources.
+
+## Inputs
+
+No inputs.
+
+## Outputs
+
+No outputs.
+<!-- END_TF_DOCS -->