terraform-output

terraform-output action

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

Retrieve the root-level outputs from a Terraform configuration.

Inputs

• path

  Path to the Terraform root module

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

• workspace

  Terraform workspace to get outputs from

  • Type: string
  • Optional
  • Default: default

• 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

Environment Variables

• 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_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
    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

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 value example.com.

Primitive types (string, number, bool)

The values for these types get cast to a string with boolean values being 'true' and 'false'.

Complex types (list/set/tuple & map/object)

The values for complex types are output as a JSON string. Terraform list, set & tuple types are cast to a JSON array, map and object types are cast to a JSON object.

These values can be used in a workflow expression by using the fromJSON function

Example usage

String

This example uses a Terraform string output to get a hostname:

on: [push]

jobs:
  show_hostname:
    runs-on: ubuntu-latest
    name: Show the hostname
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Get outputs
        uses: dflook/terraform-output@v1
        id: tf-outputs
        with:
          path: my-terraform-config

      - name: Print the hostname
        run: echo "The hostname is ${{ steps.tf-outputs.outputs.hostname }}"

Complex output

This example gets information from object and array(object) outputs.

With this Terraform config:

output "vpc" {
  value = aws_vpc.test
}
output "subnets" {
  value = [aws_subnet.a, aws_subnet.b, aws_subnet.c]
}

We can use the workflow:

jobs:
  output_example:
    runs-on: ubuntu-latest
    name: An example of workflow expressions with terraform output
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Get outputs
        uses: dflook/terraform-output@v1
        id: tf-outputs
        with:
          path: my-terraform-config

      - name: Print VPC
        run: |
          echo "The vpc-id is ${{ fromJson(steps.tf-outputs.outputs.vpc).id }}"
          echo "The subnet-ids are ${{ join(fromJson(steps.tf-outputs.outputs.subnets).*.id) }}"          

Which will print to the workflow log:

The vpc-id is vpc-01463b6b84e1454ce
The subnet-ids are subnet-053008016a2c1768c,subnet-07d4ce437c43eba2f,subnet-0a5f8c3a20023b8c0