This is one of a suite of OpenTofu related actions - find them at dflook/terraform-github-actions.

Check for drift in OpenTofu managed resources. This action runs the tofu plan command, and fails the build if any changes are required. This is intended to run on a schedule to notify if manual changes to your infrastructure have been made.

• path

  Path to the OpenTofu root module to check

  • Type: string
  • Optional
  • Default: The action workspace

• workspace

  OpenTofu workspace to run the plan in

  • Type: string
  • Optional
  • Default: default

• variables

  Variables to set for the tofu plan. This should be valid OpenTofu syntax - like a variable definition file.

  Variables set here override any given in var_files.

  with:
    variables: |
      image_id = "${{ secrets.AMI_ID }}"
      availability_zone_names = [
        "us-east-1a",
        "us-west-1c",
      ]

  • Type: string
  • Optional

• var_file

  List of tfvars files to use, one per line. Paths should be relative to the GitHub Actions workspace

  with:
    var_file: |
      common.tfvars
      prod.tfvars

  • Type: string
  • Optional

• backend_config

  List of OpenTofu backend config values, one per line.

  with:
    backend_config: token=${{ secrets.BACKEND_TOKEN }}

  • Type: string
  • Optional

• backend_config_file

  List of OpenTofu backend config files to use, one per line. Paths should be relative to the GitHub Actions workspace

  with:
    backend_config_file: prod.backend.tfvars

  • Type: string
  • Optional

• parallelism

  Limit the number of concurrent operations

  • Type: number
  • Optional
  • Default: The OpenTofu default (10).

• failure-reason

  When the job outcome is failure because the there are outstanding changes to apply, this will be set to 'changes-to-apply'. If the job fails for any other reason this will not be set. This can be used with the Actions expression syntax to conditionally run a step when there are changes to apply.

  • Type: string

• GITHUB_DOT_COM_TOKEN

  This is used to specify a token for GitHub.com when the action is running on a GitHub Enterprise instance. This is only used for downloading OpenTofu binaries from GitHub.com. If this is not set, an unauthenticated request will be made to GitHub.com to download the binary, which may be rate limited.

  • Type: string
  • Optional

• TERRAFORM_CLOUD_TOKENS

  API tokens for cloud hosts, of the form <host>=<token>. Multiple tokens may be specified, one per line. These tokens may be used with the remote backend and for fetching required modules from the registry.

  e.g:

  env:
    TERRAFORM_CLOUD_TOKENS: app.terraform.io=${{ secrets.TF_CLOUD_TOKEN }}

  With other registries:

  env:
    TERRAFORM_CLOUD_TOKENS: |
      app.terraform.io=${{ secrets.TF_CLOUD_TOKEN }}
      tofu.example.com=${{ secrets.TF_REGISTRY_TOKEN }}

  • Type: string
  • Optional

• TERRAFORM_SSH_KEY

  A SSH private key that OpenTofu will use to fetch git/mercurial module sources.

  This should be in PEM format.

  For example:

  env:
    TERRAFORM_SSH_KEY: ${{ secrets.TERRAFORM_SSH_KEY }}

  • Type: string
  • Optional

• TERRAFORM_HTTP_CREDENTIALS

  Credentials that will be used for fetching modules sources with git::http://, git::https://, http:// & https:// schemes.

  Credentials have the format <host>=<username>:<password>. Multiple credentials may be specified, one per line.

  Each credential is evaluated in order, and the first matching credentials are used.

  Credentials that are used by git (git::http://, git::https://) allow a path after the hostname. Paths are ignored by http:// & https:// schemes. For git module sources, a credential matches if each mentioned path segment is an exact match.

  For example:

  env:
    TERRAFORM_HTTP_CREDENTIALS: |
      example.com=dflook:${{ secrets.HTTPS_PASSWORD }}
      github.com/dflook/terraform-github-actions.git=dflook-actions:${{ secrets.ACTIONS_PAT }}
      github.com/dflook=dflook:${{ secrets.DFLOOK_PAT }}
      github.com=graham:${{ secrets.GITHUB_PAT }}  

  • Type: string
  • Optional

• TERRAFORM_PRE_RUN

  A set of commands that will be ran prior to tofu init. This can be used to customise the environment before running OpenTofu.

  The runtime environment for these actions is subject to change in minor version releases. If using this environment variable, specify the minor version of the action to use.

  The runtime image is currently based on debian:bookworm, with the command run using bash -xeo pipefail.

  For example:

  env:
    TERRAFORM_PRE_RUN: |
      # Install latest Azure CLI
      curl -skL https://aka.ms/InstallAzureCLIDeb | bash
  
      # Install postgres client
      apt-get install -y --no-install-recommends postgresql-client

  • Type: string
  • Optional

This example workflow runs every morning and will fail if there has been unexpected changes to your infrastructure.

name: Check for infrastructure drift

on:
  schedule:
    - cron:  "0 8 * * *"

jobs:
  check_drift:
    runs-on: ubuntu-latest
    name: Check for drift of OpenTofu configuration
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Check
        uses: dflook/tofu-check@v2
        with:
          path: my-tofu-configuration

This example executes a run step only if there are changes to apply.

name: Check for infrastructure drift

on:
  schedule:
    - cron:  "0 8 * * *"

jobs:
  check_drift:
    runs-on: ubuntu-latest
    name: Check for drift of OpenTofu configuration
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Check
        uses: dflook/tofu-check@v2
        id: check
        with:
          path: my-tofu-configuration

      - name: Changes detected
        if: ${{ failure() && steps.check.outputs.failure-reason == 'changes-to-apply' }}
        run: echo "There are outstanding changes to apply"