Pod Info on Mount

Status

Overview

CSI avoids encoding Kubernetes specific information in to the specification, since it aims to support multiple orchestration systems (beyond just Kubernetes).

This can be problematic because some CSI drivers require information about the workload (e.g. which pod is referencing this volume), and CSI does not provide this information natively to drivers.

Pod Info on Mount with CSI Driver Object

The CSIDriver Object enables CSI Drivers to specify how Kubernetes should interact with it.

Specifically the podInfoOnMount field instructs Kubernetes that the CSI driver requires additional pod information (like podName, podUID, etc.) during mount operations.

For example, the existence of the following object would cause Kubernetes to add pod information at mount time to the NodePublishVolumeRequest.volume_context map.

apiVersion: storage.k8s.io/v1
kind: CSIDriver
metadata:
  name: testcsidriver.example.com
spec:
  podInfoOnMount: true

If the podInfoOnMount field is set to true, during mount, Kubelet will add the following key/values to the volume_context field in the CSI NodePublishVolumeRequest:

• csi.storage.k8s.io/pod.name: {pod.Name}
• csi.storage.k8s.io/pod.namespace: {pod.Namespace}
• csi.storage.k8s.io/pod.uid: {pod.UID}
• csi.storage.k8s.io/serviceAccount.name: {pod.Spec.ServiceAccountName}

The CSIDriver object should be manually included in the driver manifests.

Previously, the cluster-driver-registrar sidecar container could be used to create the object. Once the flags to this container are configured correctly, it will automatically create a CSIDriver Object when it starts with the correct fields set.

Alpha Functionality

In alpha, this feature was enabled by setting the podInfoOnMountVersion field in the CSIDriver Object CRD to v1.

apiVersion: csi.storage.k8s.io/v1alpha1
kind: CSIDriver
metadata:
  name: testcsidriver.example.com
spec:
  podInfoOnMountVersion: v1