action.yml

---
name: Stop EC2 actions runner
description: Deregisters and terminates a self-hosted GitHub actions repository runner

inputs:
  aws-region:
    description: AWS region, e.g. eu-west-1
    required: true
  aws-access-key-id:
    description: AWS access key ID (pass via GitHub secret). Required only if **not** using OIDC
    required: false
  aws-secret-access-key:
    description: AWS secret access key (pass via GitHub secret). Required only if **not** using OIDC
    required: false
  aws-role-to-assume:
    description: AWS IAM role (ARN) to assume, for terminating the instance. Required if using OIDC (AssumeRoleWithWebIdentity)
    required: false
  github-token:
    description: GitHub auth token (PAT with repo scope, pass via GitHub secret). Optional if using ephemeral runners
    required: false
  github-repo:
    description: GitHub repository, e.g. ghost/example. Optional, defaults to the repository where the workflow is run
    default: ${{ github.repository }}
    required: false
  runner-id:
    description: GitHub repository runner ID, e.g. 53. Optional if using ephemeral runners
    required: false
  instance-id:
    description: EC2 instance id, e.g. i-0ab3a789090bd84c7
    required: true

runs:
  using: composite
  steps:

    - id: auth
      uses: aws-actions/configure-aws-credentials@v1
      with:
        aws-region: ${{ inputs.aws-region }}
        aws-access-key-id: ${{ inputs.aws-access-key-id }}
        aws-secret-access-key: ${{ inputs.aws-secret-access-key }}
        role-to-assume: ${{ inputs.aws-role-to-assume }}
        role-session-name: ec2-actions-runner-stop
        role-duration-seconds: 900

    - id: main
      shell: bash
      run: |
        # We do not fail the job on missing runner ID, because offline and ephemeral runners are automatically deregistered
        if [ -n "$RUNNER_ID" ]; then
            echo "Deregistering GitHub repository runner: $RUNNER_ID ..."
            gh api -X DELETE "repos/$GH_REPO/actions/runners/$RUNNER_ID" \
              || echo "WARN: Failed to deregister GitHub repository runner (GitHub API call failed)"
        fi
        
        # Failure to terminate the EC2 instance will incur unnecessary costs, so we fail the job to ensure the user notices
        if [ -z "$INSTANCE_ID" ]; then
            echo "ERROR: Unable to terminate EC2 instance (instance ID not available)"
            exit 1
        else
            echo "Terminating EC2 instance: $INSTANCE_ID ..."
            aws ec2 terminate-instances --instance-ids "$INSTANCE_ID" > /dev/null
            echo "Repository runner stopped"
        fi
      env:
        GH_TOKEN: ${{ inputs.github-token }}
        AWS_DEFAULT_REGION: ${{ inputs.aws-region }}
        RUNNER_ID: ${{ inputs.runner-id }}
        GH_REPO: ${{ inputs.github-repo }}
        INSTANCE_ID: ${{ inputs.instance-id }}