Create a Google Service Account: You create a dedicated Google service account specifically for your application's interaction with the private Cloud Storage bucket. This allows you to grant precise IAM permissions to this service account on the bucket (e.g., roles/storage.objectViewer or roles/storage.
objectCreator).
* Create a Kubernetes ServiceAccount: You create a Kubernetes ServiceAccount within your GKE cluster. This is the identity that your application Pods will assume within the cluster.
* Configure Workload Identity Federation: You establish a trust relationship between the Kubernetes ServiceAccount and the Google service account using Workload Identity Federation. This involves configuring IAM policies that allow the Kubernetes ServiceAccount to impersonate the Google service account.
* Annotate Pods with the Kubernetes ServiceAccount: You associate the created Kubernetes ServiceAccount with your application Pods. When the application in these Pods makes a call to the Cloud Storage API, the Workload Identity agent running on the GKE nodes automatically exchanges the Kubernetes ServiceAccount token for a short-lived Google Cloud access token for the associated Google service account.
This approach offers several security advantages and aligns with Google's recommended practices:
* Principle of Least Privilege: The Google service account is granted only the necessary permissions to access the specific Cloud Storage bucket.
* No Service Account Keys to Manage: You avoid the security risks associated with creating, storing, and rotating service account keys.
* Auditable Authentication: All API calls are attributed to the specific Google service account, providing better auditability.
* Simplified Management: Workload Identity Federation automates the credential management process for your application.
Google Cloud Documentation References:
* Workload Identity: https://cloud.google.com/kubernetes-engine/docs/how-to/workload-identity 1 - This is the primary documentation explaining how to use Workload Identity to allow applications in GKE to access Google Cloud services securely without using service account keys.