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terraform-plan action

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

This actions generates a terraform plan. If the triggering event relates to a PR it will add a comment on the PR containing the generated plan.

The GITHUB_TOKEN environment variable is must be set for the PR comment to be added. The action can be run on other events, which prints the plan to the workflow log.

The dflook/terraform-apply action can be used to apply the generated plan.

Inputs

  • path

    Path to the terraform configuration

    • Type: string
    • Required

  • workspace

    Terraform workspace to run the plan for

    • Type: string
    • Optional
    • Default: default

  • label

    An 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 terraform-apply command.

    • 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.

    ⚠️ Secret values are not masked in the PR comment. Set a label to avoid revealing the variables in the PR.

    • Type: string
    • Optional

  • var

    ⚠️ Deprecated: Use the variables input instead.

    Comma separated list of terraform vars to set.

    This is deprecated due to the following limitations:

    • Only primitive types can be set with var - number, bool and string.
    • String values may not contain a comma.
    • Values set with var will be overridden by values contained in var_files

    You can change from var to variables by putting each variable on a separate line and ensuring each string value is quoted.

    For example:

    with:
  var: instance_type=m5.xlarge,nat_type=instance

    Becomes:

    with:
  variables: |
    instance_type="m5.xlarge"
    nat_type="instance"
    • Type: string
    • Optional

  • var_file

    Comma separated list of tfvars files to use. Paths should be relative to the GitHub Actions workspace

    • Type: string
    • Optional

  • backend_config

    Comma separated list of terraform backend config values.

    • Type: string
    • Optional

  • backend_config_file

    Comma separated list of terraform backend config files to use. Paths should be relative to the GitHub Actions workspace

    • Type: string
    • Optional

  • parallelism

    Limit the number of concurrent operations

    • Type: number
    • Optional
    • Default: 10

  • add_github_comment

    The default is true, which adds a comment to the PR with the generated plan. Set to false to disable the comment - the plan will still appear in the workflow log.

    • Type: bool
    • Optional
    • Default: true

Environment Variables

  • GITHUB_TOKEN

    The GitHub authorization token to use to create comments on a PR. 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 }}
    • Type: string
    • Optional

  • TERRAFORM_CLOUD_TOKENS

    API tokens for terraform 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 for terraform cloud:

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

    With Terraform Enterprise or 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

  • TF_PLAN_COLLAPSE_LENGTH

    When PR comments are enabled, the terraform output is included in a collapsable pane.

    If a terraform plan has fewer lines than this value, the pane is expanded by default when the comment is displayed.

    env:
  TF_PLAN_COLLAPSE_LENGTH: 30
    • Type: integer
    • Optional
    • Default: 10

Outputs

  • changes

    Set to 'true' if the plan would apply any changes, 'false' if it wouldn't.

    Note that with terraform <0.13 an apply may still be needed to update any outputs, even if no resources would change. With terraform >=0.13 this is correctly set to 'true' whenever an apply needs to be run.

Example usage

Automatically generating a plan

This example workflow runs on every push to an open pull request, and create or updates a comment with the terraform plan

name: PR Plan

on: [pull_request]

jobs:
  plan:
    runs-on: ubuntu-latest
    name: Create terraform plan
    env:
      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}            
    steps:
      - name: Checkout
        uses: actions/checkout@v2

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

A full example of inputs

This example workflow demonstrates most of the available inputs:

  • The environment variables are set at the workflow level.
  • The PR comment will be labelled production, and the plan will use the prod workspace.
  • Variables are read from env/prod.tfvars, with turbo_mode overridden to true.
  • The backend config is taken from env/prod.backend, and the token is set from a secret.
name: PR Plan

on: [pull_request]

env:
  GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
  TERRAFORM_CLOUD_TOKENS: terraform.example.com=${{ secrets.TF_REGISTRY_TOKEN }}
  TERRAFORM_SSH_KEY: ${{ secrets.TERRAFORM_SSH_KEY }}

jobs:
  plan:
    runs-on: ubuntu-latest
    name: Create terraform plan
    steps:
      - name: Checkout
        uses: actions/checkout@v2

      - name: terraform plan
        uses: dflook/terraform-plan@v1
        with:
          path: my-terraform-config
          label: production
          workspace: prod
          var_file: env/prod.tfvars
          variables:
            turbo_mode=true
          backend_config_file: env/prod.backend
          backend_config: token=${{ secrets.BACKEND_TOKEN }}

Generating a plan using a comment

This workflow generates a plan on demand, triggered by someone commenting terraform plan on the PR. The action will create or update a comment on the PR with the generated plan.

name: Terraform Plan

on: [issue_comment]

jobs:
  plan:
    if: github.event.issue.pull_request && contains(github.event.comment.body, 'terraform plan')
    runs-on: ubuntu-latest
    name: Create terraform plan
    env:
      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
    steps:
      - name: Checkout
        uses: actions/checkout@v2
        with:
          ref: refs/pull/${{ github.event.issue.number }}/merge

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