terraform-apply action

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

This action applies a Terraform plan. The default behaviour is to apply the plan that has been added to a PR using the dflook/terraform-plan action.

If the plan is not found or has changed, then the apply action will fail. This is to ensure that the action only applies changes that have been reviewed by a human.

You can instead set auto_approve: true which will generate a plan and apply it immediately, without looking for a plan attached to a PR.

Demo

This a demo of the process for apply a Terraform change using the dflook/terraform-plan and dflook/terraform-apply actions.

GitHub

To make best use of this action, require that the plan is always reviewed before merging the PR to approve. You can enforce this in github by going to the branch settings for the repo and enable protection for the main branch:

1. Enable 'Require pull request reviews before merging'
2. Check 'Dismiss stale pull request approvals when new commits are pushed'
3. Enable 'Require status checks to pass before merging', and select the job that runs the plan.
4. Enable 'Require branches to be up to date before merging'

Inputs

These input values must be the same as any dflook/terraform-plan for the same configuration. (unless auto_approve: true)

• path

  Path to the Terraform root module to apply

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

• workspace

  Terraform workspace to run the apply in

  • Type: string
  • Optional
  • Default: default

• label

  A friendly name for the environment the Terraform configuration is for. This will be used in the PR comment for easy identification.

  It must be the same as the label used in the corresponding dflook/terraform-plan action.

  • Type: string
  • Optional

• variables

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

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

  Variables set here override any given in var_files.

  • 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 Terraform backend config values, one per line.

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

  • Type: string
  • Optional

• backend_config_file

  List of Terraform 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

• replace

  List of resources to replace, one per line.

  with:
    replace: |
      kubernetes_secret.tls_cert_public
      kubernetes_secret.tls_cert_private

  • Type: string
  • Optional

• target

  List of resources to apply, one per line. The apply operation will be limited to these resources and their dependencies.

  with:
    target: |
      kubernetes_secret.tls_cert_public
      kubernetes_secret.tls_cert_private

  • Type: string
  • Optional

• destroy

  Set to true to destroy all resources.

  This generates and applies a plan in destroy mode.

  • Type: boolean
  • Optional
  • Default: false

• plan_path

  Path to a plan file to apply. This would have been generated by a previous dflook/terraform-plan action.

  The default behaviour when this is not set is to generate a plan from the current configuration and compare it to the plan attached to the PR comment. If it is logically the same, the plan will be applied.

  When this is set to a plan file, the plan will not be generated again. If it is the exact same plan as the one attached to the PR comment, it will be applied. This will be faster than generating a new plan.

  There are downsides to applying a stored plan:

  • The plan may contain sensitive information so must be stored securely, possibly outside of GitHub.
  • It does not account for any changes that have occurred since it was generated, and may no longer be correct.
  • Plans must be generated and applied in strict order. Multiple open PRs will cause conflicts if they are applied out of order.
  • Plans are not portable between platforms.
  • Terraform and provider versions must match between the plan generation and apply.

  When auto_approve is set to true, the plan will be applied without checking if it is the same as the one attached to the PR comment.

  • Type: string
  • Optional

• auto_approve

  When set to true, plans are always applied.

  The default is false, which requires plans to have been added to a pull request comment.

  • Type: bool
  • Optional
  • Default: false

• parallelism

  Limit the number of concurrent operations

  • Type: number
  • Optional
  • Default: The terraform default (10)

Outputs

• json_plan_path

  This is the path to the generated plan in JSON Output Format The path is relative to the Actions workspace.

  This won't be set if the backend type is remote - Terraform does not support saving remote plans.

• text_plan_path

  This is the path to the generated plan in a human-readable format. The path is relative to the Actions workspace. This won't be set if auto_approve is true while using a remote backend.

• failure-reason

  When the job outcome is failure, this output may be set. The value may be one of:

  • apply-failed - The Terraform apply operation failed.
  • plan-changed - The approved plan is no longer accurate, so the apply will not be attempted.
  • state-locked - The Terraform state lock could not be obtained because it was already locked.

  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 steps.

• lock-info

  When the job outcome is failure and the failure-reason is state-locked, this output will be set.

  It is a json object containing any available state lock information and typically has the form:

  {
    "ID": "838fbfde-c5cd-297f-84a4-d7578b4a4880",
    "Path": "terraform-github-actions/test-unlock-state",
    "Operation": "OperationTypeApply",
    "Who": "root@e9d43b0c6478",
    "Version": "1.3.7",
    "Created": "2023-01-28 00:16:41.560904373 +0000 UTC",
    "Info": ""
  }

• run_id

  If the root module uses the remote or cloud backend in remote execution mode, this output will be set to the remote run id.

  • Type: string

• Terraform Outputs

  An action output will be created for each output of the Terraform configuration.

  For example, with the Terraform config:

  output "service_hostname" {
    value = "example.com"
  }

  Running this action will produce a service_hostname output with the same value. See terraform-output for details.

Environment Variables

• GITHUB_TOKEN

  The GitHub authorization token to use to fetch an approved plan from a PR. This must belong to the same user/app as the token used by the terraform-plan action. The token provided by GitHub Actions can be used - it can be passed by using the ${{ secrets.GITHUB_TOKEN }} expression, e.g.

  env:
    GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

  The token provided by GitHub Actions has default permissions at GitHub's whim. You can see what it is for your repo under the repo settings.

  The minimum permissions are pull-requests: write. It will also likely need contents: read so the job can checkout the repo.

  You can also use any other App token that has pull-requests: write permission.

  You can use a fine-grained Personal Access Token which has repository permissions:

  • Read access to metadata
  • Read and Write access to pull requests

  You can also use a classic Personal Access Token which has the repo scope.

  • Type: string
  • Optional

• TERRAFORM_ACTIONS_GITHUB_TOKEN

  When this is set it is used instead of GITHUB_TOKEN, with the same behaviour. The GitHub Terraform provider also uses the GITHUB_TOKEN so this can be used to make the github actions and the Terraform provider use different tokens.

  • Type: string
  • Optional

• 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=${{ secrets.TF_CLOUD_TOKEN }}
      terraform.example.com=${{ secrets.TF_REGISTRY_TOKEN }}

  • Type: string
  • Optional

• TERRAFORM_SSH_KEY

  A SSH private key that Terraform will use to fetch git module sources.

  This should be in PEM format.

  For example:

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

  • Type: string
  • Optional

• TERRAFORM_PRE_RUN

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

  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:bullseye, 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

• 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

Workflow events

When applying a plan from a PR comment (auto_approve is the default of false), the workflow can be triggered by the following events:

• pull_request
• pull_request_review_comment
• pull_request_target
• pull_request_review
• issue_comment, if the comment is on a PR (see below)
• push, if the pushed commit came from a PR (see below)
• repository_dispatch, if the client payload includes the pull_request url (see below)

When auto_approve is set to true, the workflow can be triggered by any event.

issue_comment

This event triggers workflows when a comment is made in a Issue or a Pull Request. Since running the action will only work in the context of a PR, the workflow should check that the comment is on a PR before running.

Also take care to checkout the PR ref.

jobs:
  apply:
    if: ${{ github.event.issue.pull_request }}
    runs-on: ubuntu-latest
    env:
      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          ref: refs/pull/${{ github.event.issue.number }}/merge

      - name: terraform apply
        uses: dflook/terraform-apply@v1
        with:
          path: my-terraform-config

push

The pushed commit must have come from a Pull Request. Typically this is used to trigger a workflow that runs on the main branch after a PR has been merged.

repository_dispatch

This event can be used to trigger a workflow from another workflow. The client payload must include the pull_request api url of where the plan PR comment can be found.

A minimal example payload looks like:

{
  "pull_request": {
    "url": "https://api.github.com/repos/dflook/terraform-github-actions/pulls/1"
  }
}

Example usage

Apply PR approved plans

This example workflow runs for every push to main. If the commit came from a PR that has been merged, applies the plan from the PR.

name: Apply

on:
  push:
    branches:
      - main

permissions:
  contents: read
  pull-requests: write

jobs:
  apply:
    runs-on: ubuntu-latest
    name: Apply approved plan
    env:
      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: terraform apply
        uses: dflook/terraform-apply@v1
        with:
          path: my-terraform-config

Always apply changes

This example workflow runs for every push to main. Changes are planned and applied.

name: Apply

on:
  push:
    branches:
      - main

jobs:
  apply:
    runs-on: ubuntu-latest
    name: Apply Terraform
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: terraform apply
        uses: dflook/terraform-apply@v1
        with:
          path: my-terraform-config
          auto_approve: true

Apply specific resources

This example workflow runs every morning and updates a TLS certificate if necessary.

name: Rotate certs

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

jobs:
  apply:
    runs-on: ubuntu-latest
    name: Rotate certs
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: terraform apply
        uses: dflook/terraform-apply@v1
        with:
          path: my-terraform-config
          auto_approve: true
          target: |
            kubernetes_secret.tls_cert_public
            kubernetes_secret.tls_cert_private

Applying a plan using a comment

This workflow applies a plan on demand, triggered by someone commenting terraform apply on the PR. The plan is taken from an existing comment generated by the dflook/terraform-plan action.

name: Terraform Apply

on: [issue_comment]

jobs:
  apply:
    if: ${{ github.event.issue.pull_request && contains(github.event.comment.body, 'terraform apply') }}
    runs-on: ubuntu-latest
    name: Apply Terraform plan
    env:
      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          ref: refs/pull/${{ github.event.issue.number }}/merge

      - name: Terraform apply
        uses: dflook/terraform-apply@v1
        with:
          path: my-terraform-config

This example retries the terraform apply operation if it fails.

name: Apply plan

on:
  push:
    branches:
      - main

permissions:
  contents: read
  pull-requests: write

jobs:
  plan:
    runs-on: ubuntu-latest
    name: Apply Terraform plan
    env:
      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: terraform apply
        uses: dflook/terraform-apply@v1
        continue-on-error: true
        id: first_try
        with:
          path: terraform

      - name: Retry failed apply
        uses: dflook/terraform-apply@v1
        if: ${{ steps.first_try.outputs.failure-reason == 'apply-failed' }}
        with:
          path: terraform
          auto_approve: true