Configuring OpenID Connect in Azure

概要

OpenID Connect (OIDC) allows your GitHub Actions workflows to access resources in Azure, without needing to store the Azure credentials as long-lived GitHub secrets.

This guide gives an overview of how to configure Azure to trust GitHub's OIDC as a federated identity, and includes a workflow example for the azure/login action that uses tokens to authenticate to Azure and access resources.

必要な環境

• To learn the basic concepts of how GitHub uses OpenID Connect (OIDC), and its architecture and benefits, see "About security hardening with OpenID Connect."

• Before proceeding, you must plan your security strategy to ensure that access tokens are only allocated in a predictable way. To control how your cloud provider issues access tokens, you must define at least one condition, so that untrusted repositories can’t request access tokens for your cloud resources. For more information, see "Configuring the OIDC trust with the cloud."

Adding the Federated Credentials to Azure

GitHub's OIDC provider works with Azure's workload identity federation. For an overview, see Microsoft's documentation at "Workload identity federation."

To configure the OIDC identity provider in Azure, you will need to perform the following configuration. For instructions on making these changes, refer to the Azure documentation.

1. Create an Azure Active Directory application and a service principal.
2. Add federated credentials for the Azure Active Directory application.
3. Create GitHub secrets for storing Azure configuration.

Additional guidance for configuring the identity provider:

• For security hardening, make sure you've reviewed "Configuring the OIDC trust with the cloud". For an example, see "Configuring the subject in your cloud provider".
• For the audience setting, api://AzureADTokenExchange is the recommended value, but you can also specify other values here.

GitHub Actions ワークフローを更新する

To update your workflows for OIDC, you will need to make two changes to your YAML:

1. Add permissions settings for the token.
2. Use the azure/login action to exchange the OIDC token (JWT) for a cloud access token.

Adding permissions settings

 The job or workflow run requires a permissions setting with id-token: write. You won't be able to request the OIDC JWT ID token if the permissions setting for id-token is set to read or none.

The id-token: write setting allows the JWT to be requested from GitHub's OIDC provider using one of these approaches:

• Using environment variables on the runner (ACTIONS_ID_TOKEN_REQUEST_URL and ACTIONS_ID_TOKEN_REQUEST_TOKEN).
• Using getIDToken() from the Actions toolkit.

If you only need to fetch an OIDC token for a single job, then this permission can be set within that job. 例:

permissions:
  id-token: write

You may need to specify additional permissions here, depending on your workflow's requirements.

Requesting the access token

The azure/login action receives a JWT from the GitHub OIDC provider, and then requests an access token from Azure. For more information, see the azure/login documentation.

The following example exchanges an OIDC ID token with Azure to receive an access token, which can then be used to access cloud resources.

name: Run Azure Login with OIDC
on: [push]

permissions:
      id-token: write
      contents: read
jobs: 
  build-and-deploy:
    runs-on: ubuntu-latest
    steps:
      - name: 'Az CLI login'
        uses: azure/login@v1
        with:
          client-id: ${{ secrets.AZURE_CLIENT_ID }}
          tenant-id: ${{ secrets.AZURE_TENANT_ID }}
          subscription-id: ${{ secrets.AZURE_SUBSCRIPTION_ID }}

      - name: 'Run az commands'
        run: |
          az account show
          az group list