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Azure RBAC on Azure Arc-enabled Kubernetes clusters

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Kubernetes ClusterRoleBinding and RoleBinding object types help to define authorization in Kubernetes natively. With Azure role-based access control (Azure RBAC), you can use Microsoft Entra ID and role assignments in Azure to control authorization checks on the cluster. This allows the benefits of Azure role assignments, such as activity logs showing all Azure RBAC changes to an Azure resource, to be used with your Azure Arc-enabled Kubernetes cluster.

Architecture

Diagram showing Azure RBAC architecture.

In order to route all authorization access checks to the authorization service in Azure, a webhook server (guard) is deployed on the cluster.

The apiserver of the cluster is configured to use webhook token authentication and webhook authorization so that TokenAccessReview and SubjectAccessReview requests are routed to the guard webhook server. The TokenAccessReview and SubjectAccessReview requests are triggered by requests for Kubernetes resources sent to the apiserver.

Guard then makes a checkAccess call on the authorization service in Azure to see if the requesting Microsoft Entra entity has access to the resource of concern.

If that entity has a role that permits this access, an allowed response is sent from the authorization service to guard. Guard, in turn, sends an allowed response to the apiserver, enabling the calling entity to access the requested Kubernetes resource.

If the entity doesn't have a role that permits this access, a denied response is sent from the authorization service to guard. Guard sends a denied response to the apiserver, giving the calling entity a 403 forbidden error on the requested resource.

Next steps