Terraform GitHub Actions with GCP

Terraform GitHub Actions allow you to execute Terraform commands within GitHub Actions.

The output of the actions can be viewed from the Actions tab in the main repository view. If the actions are executed on a pull request event, a comment may be posted on the pull request.

Terraform GitHub Actions are a single GitHub Action that executes different Terraform subcommands depending on the content of the GitHub Actions YAML file.

Success Criteria

An exit code of 0 is considered a successful execution.

Usage

The most common workflow is to run terraform fmt, terraform init, terraform validate, terraform plan, and terraform taint on all of the Terraform files in the root of the repository when a pull request is opened or updated. A comment will be posted to the pull request depending on the output of the Terraform subcommand being executed. This workflow can be configured by adding the following content to the GitHub Actions workflow YAML file.

name: 'Terraform GitHub Actions'
on:
  - pull_request
env:
  tf_version: 'latest'
  tf_working_dir: '.'
jobs:
  terraform:
    name: 'Terraform'
    runs-on: ubuntu-latest
    steps:
      - name: Set GCP environment
        id: set_gcp_env
        run: echo ::set-env name=BRANCH_NAME::$(echo ${GITHUB_BASE_REF#refs/heads/})

      - name: configure gcloud
        id: config_gcloud
        uses: GoogleCloudPlatform/github-actions/setup-gcloud@master
        with:
          version: "latest"
          service_account_email: ${{ secrets.GCP_SA_EMAIL }}
          service_account_key: ${{ secrets.GCP_SA_KEY }}

      - name: checkout
        id: checkout_code
        uses: actions/checkout@v2

      - name: set GCP project
        id: config_project
        run: gcloud config set project xxxx

      - name: "Decrypt key service account"
        id: decrypt_SA
        run: gcloud secrets versions access latest --secret=test-terraform-key --project="xxxx" 
        working-directory: "environments/${{ env.BRANCH_NAME }}"

      - name: "Terraform Init"
        id: terraform_init
        uses: ops18/terraform-github-actions@master
        with:
          tf_actions_version: ${{ env.TERRAFORM_VERSION }}
          tf_actions_comment: "false"
          tf_actions_working_dir: environments/${{ env.BRANCH_NAME }}
          tf_actions_subcommand: init
        env:
          GCP_SA_KEY: ${{ secrets.GCP_SA_KEY}}
      - name: "Terraform Validate"
        id: terraform_validate
        uses: ops18/terraform-github-actions@master
        with:
          tf_actions_version: ${{ env.TERRAFORM_VERSION }}
          tf_actions_comment: "false"
          tf_actions_working_dir: environments/${{ env.BRANCH_NAME }}
          tf_actions_subcommand: validate
        env:
          GCP_SA_KEY: ${{ secrets.GCP_SA_KEY}} 
      - name: "Terraform Plan"
        id: terraform_plan
        uses: ops18/terraform-github-actions@master
        with:
          tf_actions_version: ${{ env.TERRAFORM_VERSION }}
          tf_actions_comment: "false"
          tf_actions_working_dir: environments/${{ env.BRANCH_NAME }}
          tf_actions_subcommand: plan
        env:
          GCP_SA_KEY: ${{ secrets.GCP_SA_KEY}}
          
      - name: "Terraform Apply"
        uses: ops18/terraform-github-actions@master
        id: terraform_apply
        with:
          tf_actions_version: ${{ env.TERRAFORM_VERSION }}
          tf_actions_comment: "false"
          tf_actions_working_dir: environments/${{ env.BRANCH_NAME }}
          tf_actions_subcommand: apply
        env:
          GCP_SA_KEY: ${{ secrets.GCP_SA_KEY}}

This was a simplified example showing the basic features of these Terraform GitHub Actions. Please refer to the examples within the examples directory for other common workflows.

Inputs

Inputs configure Terraform GitHub Actions to perform different actions.

• tf_actions_subcommand - (Required) The Terraform subcommand to execute. Valid values are fmt, init, validate, plan, and apply.
• tf_actions_version - (Required) The Terraform version to install and execute. If set to latest, the latest stable version will be used.
• tf_actions_cli_credentials_hostname - (Optional) Hostname for the CLI credentials file. Defaults to app.terraform.io.
• tf_actions_cli_credentials_token - (Optional) Token for the CLI credentials file.
• tf_actions_comment - (Optional) Whether or not to comment on GitHub pull requests. Defaults to true.
• tf_actions_working_dir - (Optional) The working directory to change into before executing Terraform subcommands. Defaults to . which means use the root of the GitHub repository.
• tf_actions_fmt_write - (Optional) Whether or not to write fmt changes to source files. Defaults to false.

Outputs

Outputs are used to pass information to subsequent GitHub Actions steps.

• tf_actions_output - The Terraform outputs in (stringified) JSON format.
• tf_actions_plan_has_changes - 'true' if the Terraform plan contained changes, otherwise 'false'.
• tf_actions_plan_output - The Terraform plan output.
• tf_actions_fmt_written - Whether or not the Terraform formatting from fmt was written to source files.

Secrets

Secrets are similar to inputs except that they are encrypted and only used by GitHub Actions. It's a convenient way to keep sensitive data out of the GitHub Actions workflow YAML file.

• GITHUB_TOKEN - (Optional) The GitHub API token used to post comments to pull requests. Not required if the tf_actions_comment input is set to false.
• GCP_SA_KEY - (Optional) The Google SA Key used to grant permission no need to pass code in provider and repository.

WARNING: These secrets could be exposed if the action is executed on a malicious Terraform file. To avoid this, it is recommended not to use these Terraform GitHub Actions on repositories where untrusted users can submit pull requests.

Environment Variables

Environment variables are exported in the environment where the Terraform GitHub Actions are executed. This allows a user to modify the behavior of certain GitHub Actions.

The usual Terraform environment variables are supported. Here are a few of the more commonly used environment variables.

• TF_LOG
• TF_VAR_name
• TF_CLI_ARGS
• TF_CLI_ARGS_name
• TF_WORKSPACE

Other environment variables may be configured to pass data into Terraform. If the data is sensitive, consider using secrets instead.