This action allows you to authenticate as an installation of a GitHub App in your workflow. This can be a more secure way to authenticate than using a personal access token that is tied to a user account.

One use case for this would be cloning a private repository in a GitHub organization outside of the repository where the workflow is running.

• app-id (Required) - The ID of the GitHub App that you want to authenticate as. This can be found in the settings of the GitHub App.
• private-key (Required) - The private key of the GitHub App that you want to authenticate as. This can be generated in the settings of the GitHub App. Learn more about private keys. It should start with -----BEGIN RSA PRIVATE KEY----- and end with -----END RSA PRIVATE KEY-----.
• installation-id (Optional) - The ID of the installation of the GitHub App that you want to authenticate as. Only required if multiple installations of the GitHub App exist.
• set-git-credentials (Optional) - If set to true, the action will configure the git credentials for GitHub URLs. This allows you to clone private repositories if the installation has access to them.

• access-token - The access token that was generated for the installation marked as a secret. I can be used in subsequent steps to authenticate as the GitHub App installation but will not be printed to the logs. The token expires after 10 minutes.

If you want to use this action to clone a private repository, you need to grant the installation read access to the repository. You can manage the access in the settings of the installation in your organization or profile settings.

name: GitHub Actions Demo
run-name: ${{ github.actor }} is testing out GitHub Actions 🚀
on:
  workflow_dispatch:
  push:
    branches:
      - main
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: timowilhelm/github-app-authentication@v1
        with:
          app-id: ${{ secrets.APP_ID }}
          private-key: ${{ secrets.APP_PRIVATE_KEY }}
          set-git-credentials: true
      - run: |
          git clone https://github.com/<ORG_NAME>/<PRIVATE_REPO_NAME>

Inspired by https://github.com/daspn/private-actions-checkout