Authentication in a workflow

About the GITHUB_TOKEN secret

GitHub automatically creates a GITHUB_TOKEN secret to use in your workflow. You can use the GITHUB_TOKEN to authenticate in a workflow run.

When you enable GitHub Actions, GitHub installs a App GitHub on your repository. The GITHUB_TOKEN secret is a App GitHub installation access token. You can use the installation access token to authenticate on behalf of the App GitHub installed on your repository. The token's permissions are limited to the repository that contains your workflow. For more information, see "Permissions for the GITHUB_TOKEN."

Before each job begins, GitHub fetches an installation access token for the job. The token expires when the job is finished.

The token is also available in the github.token context. For more information, see "Context and expression syntax for GitHub Actions."

Using the GITHUB_TOKEN in a workflow

You can use the GITHUB_TOKEN by using the standard syntax for referencing secrets: ${{ secrets.GITHUB_TOKEN }}. Examples of using the GITHUB_TOKEN include passing the token as an input to an action, or using it to make an authenticated GitHub API request.

Cuando utilizas el GITHUB_TOKEN del repositorio para realizar tareas por parte de la app de GitHub Actions, los eventos que GITHUB_TOKEN desencadena no crearán una ejecución de flujo de trabajo. Esto impide que crees ejecuciones de flujo de trabajo recursivas por accidente. Por ejemplo, si un flujo de trabajo sube código utilizando el GITHUB_TOKEN del repositorio, no se ejecutará un nuevo flujo de trabajo aún si el repositorio contiene alguno configurado para ejecutarse cuando ocurran eventos de subida de información.

Example 1: passing the GITHUB_TOKEN as an input

This example workflow uses the labeler action, which requires the GITHUB_TOKEN as the value for the repo-token input parameter:

name: Pull request labeler

on: [ pull_request_target ]

permissions:
  contents: read
  pull-requests: write

jobs:
  triage:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/labeler@v2
        with:
          repo-token: ${{ secrets.GITHUB_TOKEN }}

Example 2: calling the REST API

You can use the GITHUB_TOKEN to make authenticated API calls. This example workflow creates an issue using the GitHub REST API:

name: Create issue on commit

on: [ push ]

jobs:
  create_commit:
    runs-on: ubuntu-latest 
    permissions:
      issues: write 
    steps:
      - name: Create issue using REST API
        run: |
          curl --request POST \
          --url https://api.github.com/repos/${{ github.repository }}/issues \
          --header 'authorization: Bearer ${{ secrets.GITHUB_TOKEN }}' \
          --header 'content-type: application/json' \
          --data '{
            "title": "Automated issue for commit: ${{ github.sha }}",
            "body": "This issue was automatically created by the GitHub Action workflow **${{ github.workflow }}**. \n\n The commit hash was: _${{ github.sha }}_."
            }' \
          --fail

Permissions for the GITHUB_TOKEN

For information about the API endpoints GitHub Apps can access with each permission, see "App GitHub Permissions."

The following table shows the permissions granted to the GITHUB_TOKEN by default. People with admin permissions to an enterprise, organization, or repository can set the default permissions to be either permissive or restricted. For information on how to set the default permissions for the GITHUB_TOKEN for your enterprise, organization, or repository, see "Enforcing GitHub Actions policies in your enterprise account," "Disabling or limiting GitHub Actions for your organization," or "Disabling or limiting GitHub Actions for a repository."

Modifying the permissions for the GITHUB_TOKEN

You can modify the permissions for the GITHUB_TOKEN in individual workflow files. If the default permissions for the GITHUB_TOKEN are restrictive, you may have to elevate the permissions to allow some actions and commands to run successfully. If the default permissions are permissive, you can edit the workflow file to remove some permissions from the GITHUB_TOKEN. As a good security practice, you should grant the GITHUB_TOKEN the least required access.

You can see the permissions that GITHUB_TOKEN had for a specific job in the "Set up job" section of the workflow run log. For more information, see "Using workflow run logs."

You can use the permissions key in your workflow file to modify permissions for the GITHUB_TOKEN for an entire workflow or for individual jobs. This allows you to configure the minimum required permissions for a workflow or job. When the permissions key is used, all unspecified permissions are set to no access, with the exception of the metadata scope, which always gets read access.

You can use the permissions key to add and remove read permissions for forked repositories, but typically you can't grant write access. The exception to this behavior is where an admin user has selected the Send write tokens to workflows from pull requests option in the GitHub Actions settings. For more information, see "Disabling or limiting GitHub Actions for a repository."

The two workflow examples earlier in this article show the permissions key being used at the workflow level, and at the job level. In Example 1 the two permissions are specified for the entire workflow. In Example 2 write access is granted for one scope for a single job.

For full details of the permissions key, see "Workflow syntax for GitHub Actions."

How the permissions are calculated for a workflow job

The permissions for the GITHUB_TOKEN are initially set to the default setting for the enterprise, organization, or repository. If the default is set to the restricted permissions at any of these levels then this will apply to the relevant repositories. For example, if you choose the restricted default at the organization level then all repositories in that organization will use the restricted permissions as the default. The permissions are then adjusted based on any configuration within the workflow file, first at the workflow level and then at the job level. Finally, if the workflow was triggered by a pull request from a forked repository, and the Send write tokens to workflows from pull requests setting is not selected, the permissions are adjusted to change any write permissions to read only.

Granting additional permissions

If you need a token that requires permissions that aren't available in the GITHUB_TOKEN, you can create a personal access token and set it as a secret in your repository:

1. Use or create a token with the appropriate permissions for that repository. For more information, see "Creating a personal access token."
2. Add the token as a secret in your workflow's repository, and refer to it using the ${{ secrets.SECRET_NAME }} syntax. For more information, see "Creating and using encrypted secrets."