action.yml

name: Self-Hosted GitHub Actions Runner on Google Cloud
description: A GitHub Action to automatically create Google Cloud VMs (GCE) and register them as self-hosted GitHub Actions runners.
author: Nils Knieling

branding:
  icon: 'server'
  color: 'blue'

inputs:
  delete_wait:
    description: >-
      Wait up to 'delete_wait' retries (10 sec each) to delete the Compute Engine VM via the gcloud CLI (default: 360 = 1 hour).
    required: false
    default: '360'
  disk_size:
    description: >-
      Boot disk size in GB for the Compute Engine VM.
    required: false
    default: '40'
  disk_type:
    description: >-
      Boot disk type for the Compute Engine VM (e.g. 'pd-standard', 'pd-balanced', 'pd-ssd').
    required: false
    default: 'pd-balanced'
  enable_external_ip:
    description: >-
      Attach an external (public) IPv4 address to the VM (true/false).
      Warning: The GitHub API requires outbound internet access. Without an external IP you must provide
      an alternative route to the internet (e.g. Cloud NAT). Default is true.
    required: false
    default: 'true'
  github_token:
    description: >-
      Fine-grained GitHub Personal Access Token (PAT) with 'Read and write' access to 'Administration' assigned.
    required: true
  image:
    description: >-
      Name of a specific Compute Engine image to create the VM from. If set, takes precedence over 'image_family'.
    required: false
    default: 'null'
  image_family:
    description: >-
      Image family to create the VM from (e.g. 'ubuntu-2404-lts-amd64').
    required: false
    default: 'ubuntu-2404-lts-amd64'
  image_project:
    description: >-
      Project against which 'image' or 'image_family' is resolved (e.g. 'ubuntu-os-cloud').
    required: false
    default: 'ubuntu-os-cloud'
  machine_type:
    description: >-
      Machine type the VM should be created with (e.g. 'e2-medium', 'n2-standard-4').
    required: false
    default: 'e2-medium'
  max_run_duration:
    description: >-
      Maximum run duration before the VM is automatically terminated.
      Accepts the gcloud duration format (e.g. '4h', '30m', '14400s') or a plain number of seconds.
      This is a safety limit to avoid orphaned VMs if 'delete' mode never runs.
    required: false
    default: '4h'
  mode:
    description: >-
      Choose either 'create' to create a new GitHub Actions Runner or 'delete' to delete a previously created one.
    required: true
  name:
    description: >-
      The name for the VM and label for the GitHub Actions Runner (must be unique within the project and conform to
      RFC1035: lowercase letters, digits and hyphens; must start with a letter).
    required: false
  network:
    description: >-
      Name of the VPC network the VM's network interface should be attached to.
    required: false
    default: 'default'
  pre_runner_script:
    description: >-
      Specifies bash commands to run before the GitHub Actions Runner starts.
      It's useful for installing dependencies with apt-get, dnf, zypper etc.
    required: false
  project:
    description: >-
      Google Cloud project ID in which the VM should be created or deleted.
      If omitted, the default project configured in the gcloud CLI is used.
    required: false
    default: 'null'
  runner_dir:
    description: >-
      GitHub Actions Runner installation directory (created automatically; no trailing slash).
    required: false
    default: '/actions-runner'
  runner_wait:
    description: >-
      Wait up to 'runner_wait' retries (10 sec each) for runner registration (default: 10 minutes).
    required: false
    default: '60'
  runner_version:
    description: >-
      GitHub Actions Runner version (omit 'v'; e.g., '2.321.0').
      'latest' will install the latest version.
      'skip' will skip the installation. A working installation is expected in the 'runner_dir'.
    required: false
    default: 'latest'
  service_account:
    description: >-
      Service account email to attach to the VM. If omitted the project default Compute Engine service account is used.
    required: false
    default: 'null'
  scopes:
    description: >-
      Comma separated list of access scopes for the attached service account.
    required: false
    default: 'cloud-platform'
  subnet:
    description: >-
      Name of the subnetwork the VM's network interface should be attached to.
    required: false
    default: 'null'
  tags:
    description: >-
      Comma separated list of network tags to apply to the VM (e.g. for firewall rules).
    required: false
    default: 'null'
  vm_wait:
    description: >-
      Wait up to 'vm_wait' retries (10 sec each) for the Compute Engine VM to start running (default: 30 = 5 min).
    required: false
    default: '30'
  zone:
    description: >-
      Compute Engine zone to create the VM in (e.g. 'europe-west1-b').
    required: false
    default: 'europe-west1-b'

outputs:
  label:
    description: >-
      This label uniquely identifies a GitHub Actions runner,
      used both to specify which runner a job should execute on via the `runs-on` property and to delete the runner when it's no longer needed.
    value: ${{ steps.gce-github-runner.outputs.label }}
  vm_name:
    description: >-
      This is the Compute Engine VM name of the runner, used to delete the VM when the runner is no longer required.
    value: ${{ steps.gce-github-runner.outputs.vm_name }}

runs:
  using: "composite"
  steps:
    - name: GitHub Actions Runner in Google Cloud
      id: gce-github-runner
      shell: bash
      working-directory: ${{ github.action_path }}
      run: bash action.sh
      env:
        INPUT_DELETE_WAIT: ${{ inputs.delete_wait }}
        INPUT_DISK_SIZE: ${{ inputs.disk_size }}
        INPUT_DISK_TYPE: ${{ inputs.disk_type }}
        INPUT_ENABLE_EXTERNAL_IP: ${{ inputs.enable_external_ip }}
        INPUT_GITHUB_TOKEN: ${{ inputs.github_token }}
        INPUT_IMAGE: ${{ inputs.image }}
        INPUT_IMAGE_FAMILY: ${{ inputs.image_family }}
        INPUT_IMAGE_PROJECT: ${{ inputs.image_project }}
        INPUT_MACHINE_TYPE: ${{ inputs.machine_type }}
        INPUT_MAX_RUN_DURATION: ${{ inputs.max_run_duration }}
        INPUT_MODE: ${{ inputs.mode }}
        INPUT_NAME: ${{ inputs.name }}
        INPUT_NETWORK: ${{ inputs.network }}
        INPUT_PRE_RUNNER_SCRIPT: ${{ inputs.pre_runner_script }}
        INPUT_PROJECT: ${{ inputs.project }}
        INPUT_RUNNER_DIR: ${{ inputs.runner_dir }}
        INPUT_RUNNER_VERSION: ${{ inputs.runner_version }}
        INPUT_RUNNER_WAIT: ${{ inputs.runner_wait }}
        INPUT_SERVICE_ACCOUNT: ${{ inputs.service_account }}
        INPUT_SCOPES: ${{ inputs.scopes }}
        INPUT_SUBNET: ${{ inputs.subnet }}
        INPUT_TAGS: ${{ inputs.tags }}
        INPUT_VM_WAIT: ${{ inputs.vm_wait }}
        INPUT_ZONE: ${{ inputs.zone }}