Note
GitHub-hosted runners are not currently supported on GitHub Enterprise Server. You can see more information about planned future support on the GitHub public roadmap.
Overview
OpenID Connect (OIDC) allows your GitHub Actions workflows to access resources in Google Cloud Platform (GCP), without needing to store the GCP credentials as long-lived GitHub secrets.
This guide gives an overview of how to configure GCP to trust GitHub's OIDC as a federated identity, and includes a workflow example for the google-github-actions/auth
action that uses tokens to authenticate to GCP and access resources.
Prerequisites
-
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 "About security hardening with OpenID Connect."
Adding a Google Cloud Workload Identity Provider
To configure the OIDC identity provider in GCP, you will need to perform the following configuration. For instructions on making these changes, refer to the GCP documentation.
- Create a new identity pool.
- Configure the mapping and add conditions.
- Connect the new pool to a service account.
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 service account to be available for configuration, it needs to be assigned to the
roles/iam.workloadIdentityUser
role. For more information, see the GCP documentation. - The Issuer URL to use:
https://HOSTNAME/_services/token
Updating your GitHub Actions workflow
To update your workflows for OIDC, you will need to make two changes to your YAML:
- Add permissions settings for the token.
- Use the
google-github-actions/auth
action to exchange the OIDC token (JWT) for a cloud access token.
Note
When environments are used in workflows or in OIDC policies, we recommend adding protection rules to the environment for additional security. For example, you can configure deployment rules on an environment to restrict which branches and tags can deploy to the environment or access environment secrets. For more information, see "Managing environments for deployment."
Adding permissions settings
The job or workflow run requires a permissions
setting with id-token: write
to allow GitHub's OIDC provider to create a JSON Web Token for every run. You won't be able to request the OIDC JWT ID token if the permissions
for id-token
is not set to write
, however this value doesn't imply granting write access to any resources, only being able to fetch and set the OIDC token for an action or step to enable authenticating with a short-lived access token. Any actual trust setting is defined using OIDC claims, for more information see "About security hardening with OpenID Connect."
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
andACTIONS_ID_TOKEN_REQUEST_TOKEN
). - Using
getIDToken()
from the Actions toolkit.
If you need to fetch an OIDC token for a workflow, then the permission can be set at the workflow level. For example:
permissions: id-token: write # This is required for requesting the JWT contents: read # This is required for actions/checkout
permissions:
id-token: write # This is required for requesting the JWT
contents: read # This is required for actions/checkout
If you only need to fetch an OIDC token for a single job, then this permission can be set within that job. For example:
permissions: id-token: write # This is required for requesting the JWT
permissions:
id-token: write # This is required for requesting the JWT
You may need to specify additional permissions here, depending on your workflow's requirements.
For reusable workflows that are owned by the same user, organization, or enterprise as the caller workflow, the OIDC token generated in the reusable workflow can be accessed from the caller's context.
For reusable workflows outside your enterprise or organization, the permissions
setting for id-token
should be explicitly set to write
at the caller workflow level or in the specific job that calls the reusable workflow.
This ensures that the OIDC token generated in the reusable workflow is only allowed to be consumed in the caller workflows when intended.
For more information, see "Reusing workflows."
Requesting the access token
The google-github-actions/auth
action receives a JWT from the GitHub OIDC provider, and then requests an access token from GCP. For more information, see the GCP documentation.
This example has a job called Get_OIDC_ID_token
that uses actions to request a list of services from GCP.
WORKLOAD-IDENTITY-PROVIDER
: Replace this with the path to your identity provider in GCP. For example,projects/example-project-id/locations/global/workloadIdentityPools/name-of-pool/providers/name-of-provider
SERVICE-ACCOUNT
: Replace this with the name of your service account in GCP.
This action exchanges a GitHub OIDC token for a Google Cloud access token, using Workload Identity Federation.
name: List services in GCP on: pull_request: branches: - main permissions: id-token: write jobs: Get_OIDC_ID_token: runs-on: ubuntu-latest steps: - id: 'auth' name: 'Authenticate to GCP' uses: 'google-github-actions/auth@f1e2d3c4b5a6f7e8d9c0b1a2c3d4e5f6a7b8c9d0' with: create_credentials_file: 'true' workload_identity_provider: 'WORKLOAD-IDENTITY-PROVIDER' service_account: 'SERVICE-ACCOUNT' - id: 'gcloud' name: 'gcloud' run: |- gcloud auth login --brief --cred-file="${{ steps.auth.outputs.credentials_file_path }}" gcloud services list
name: List services in GCP
on:
pull_request:
branches:
- main
permissions:
id-token: write
jobs:
Get_OIDC_ID_token:
runs-on: ubuntu-latest
steps:
- id: 'auth'
name: 'Authenticate to GCP'
uses: 'google-github-actions/auth@f1e2d3c4b5a6f7e8d9c0b1a2c3d4e5f6a7b8c9d0'
with:
create_credentials_file: 'true'
workload_identity_provider: 'WORKLOAD-IDENTITY-PROVIDER'
service_account: 'SERVICE-ACCOUNT'
- id: 'gcloud'
name: 'gcloud'
run: |-
gcloud auth login --brief --cred-file="${{ steps.auth.outputs.credentials_file_path }}"
gcloud services list