Troubleshooting Dependabot on GitHub Actions

Restrictions when Dependabot triggers events

Dependabot is able to trigger GitHub Actions workflows on its pull requests and comments; however, certain events are treated differently.

For workflows initiated by Dependabot (github.actor == 'dependabot[bot]') using the pull_request, pull_request_review, pull_request_review_comment, push, create, deployment, and deployment_status events, these restrictions apply:

• GITHUB_TOKEN has read-only permissions by default.
• Secrets are populated from Dependabot secrets. GitHub Actions secrets are not available.

For workflows initiated by Dependabot (github.actor == 'dependabot[bot]') using the pull_request_target event, if the base ref of the pull request was created by Dependabot (github.event.pull_request.user.login == 'dependabot[bot]'), the GITHUB_TOKEN will be read-only and secrets are not available.

These restrictions apply even if the workflow is re-run by a different actor.

For more information, see Keeping your GitHub Actions and workflows secure: Preventing pwn requests.

Troubleshooting failures when Dependabot triggers existing workflows

GitHub.comに対して Dependabot の更新プログラムを設定した後、Dependabot イベントによって既存のワークフローがトリガーされるとエラーが発生することがあります。

既定では、push、pull_request、pull_request_review、または pull_request_review_comment のイベントから Dependabot によってトリガーされる GitHub Actions ワークフローの実行は、リポジトリ フォークから開かれたかのように扱われます。 他のアクターによってトリガーされるワークフローとは異なり、これは読み取り専用の GITHUB_TOKEN を受け取り、通常使用できるシークレットにはアクセスできないことを意味します。 これにより、Dependabot によってトリガーされたときに、リポジトリへの書き込みを試みるワークフローが失敗します。

この問題を解決するには、次の 3 つの方法があります。

1. if: github.actor != 'dependabot[bot]' のような式を使用して、Dependabot によってトリガーされないようにワークフローを更新できます。 詳しくは、「ワークフローとアクションで式を評価する」を参照してください。
2. ワークフローを変更して、このような制限がない pull_request_target を含む 2 段階のプロセスを使用できます。 詳しくは、「GitHub ActionsでのDependabotの自動化」を参照してください。
3. Dependabot のアクセスによってトリガーされるワークフローをシークレットに提供し、permissions という用語で GITHUB_TOKEN の既定のスコープを広げることができます。

Some troubleshooting advice is provided in this article. You can also see GitHub Actions　のワークフロー構文.

Accessing secrets

When a Dependabot event triggers a workflow, the only secrets available to the workflow are Dependabot secrets. GitHub Actions secrets are not available. You must therefore store any secrets that are used by a workflow triggered by Dependabot events as Dependabot secrets. For more information, see Dependabot のプライベート レジストリへのアクセスの構成.

Dependabot secrets are added to the secrets context and referenced using exactly the same syntax as secrets for GitHub Actions. For more information, see GitHub Actions でのシークレットの使用.

If you have a workflow that will be triggered by Dependabot and also by other actors, the simplest solution is to store the token with the permissions required in an action and in a Dependabot secret with identical names. Then the workflow can include a single call to these secrets. If the secret for Dependabot has a different name, use conditions to specify the correct secrets for different actors to use.

For examples that use conditions, see GitHub ActionsでのDependabotの自動化.

To access a private container registry on AWS with a user name and password, a workflow must include a secret for username and password.

In this example, when Dependabot triggers the workflow, the Dependabot secrets with the names READONLY_AWS_ACCESS_KEY_ID and READONLY_AWS_ACCESS_KEY are used. If another actor triggers the workflow, the actions secrets with those names are used.

name: CI
on:
  pull_request:
    branches: [ main ]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Login to private container registry for dependencies
        uses: docker/login-action@3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c
        with:
          registry: https://1234567890.dkr.ecr.us-east-1.amazonaws.com
          username: ${{ secrets.READONLY_AWS_ACCESS_KEY_ID }}
          password: ${{ secrets.READONLY_AWS_ACCESS_KEY }}

      - name: Build the Docker image
        run: docker build . --file Dockerfile --tag my-image-name:$(date +%s)

name: CI
on:
  pull_request:
    branches: [ main ]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Login to private container registry for dependencies
        uses: docker/login-action@3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c
        with:
          registry: https://1234567890.dkr.ecr.us-east-1.amazonaws.com
          username: ${{ secrets.READONLY_AWS_ACCESS_KEY_ID }}
          password: ${{ secrets.READONLY_AWS_ACCESS_KEY }}

      - name: Build the Docker image
        run: docker build . --file Dockerfile --tag my-image-name:$(date +%s)

Changing GITHUB_TOKEN permissions

By default, GitHub Actions workflows triggered by Dependabot get a GITHUB_TOKEN with read-only permissions. You can use the permissions key in your workflow to increase the access for the token:

name: CI
on: pull_request

# Set the access for individual scopes, or use permissions: write-all
permissions:
  pull-requests: write
  issues: write
  repository-projects: write
  ...

jobs:
  ...

name: CI
on: pull_request

# Set the access for individual scopes, or use permissions: write-all
permissions:
  pull-requests: write
  issues: write
  repository-projects: write
  ...

jobs:
  ...

For more information, see 自動トークン認証.

Manually re-running a workflow

When you manually re-run a Dependabot workflow, it will run with the same privileges as before even if the user who initiated the rerun has different privileges. For more information, see ワークフローとジョブの再実行.