A GitHub Action that enforces Terraform formatting standards by running terraform fmt on all committed files. The workflow will fail if any files require reformatting.

• Automatically checks Terraform file formatting on each pull request.
• Posts detailed comments on pull requests highlighting formatting issues when the GITHUB_TOKEN is provided.
• Ensures consistency across Terraform codebases.

When the GITHUB_TOKEN is passed, the action posts a comment to the pull request. The comment includes:

• A list of files that require formatting.
• The specific differences introduced by running terraform fmt.

Example comment:

To accurately determine changed files, set the fetch-depth in the checkout step:

• Recommended: Use fetch-depth: 0 to fetch the full commit history.
• Minimum Requirement: Set fetch-depth to at least 3.

If changed files cannot be identified (e.g., shallow fetch), the action will default to checking all Terraform files, including unchanged files.

name: Enforce Terraform Format
on:
  pull_request:
    paths:
      - '**/*.tf'
      - '**/*.tfvars'

jobs:
  terraform-fmt:
    runs-on: ubuntu-latest
    permissions:
      contents: read
    steps:
      - name: Checkout the contents
        uses: actions/checkout@v4
        with:
          fetch-depth: '0' # Fetch full history for accurate file change detection

      - name: Enforce Terraform formatting
        uses: pvicol/enforce-terraform-fmt@v1.2.0
        with:
          terraform_version: '1.9.8'
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}