[Solved] MountVolume.SetUp failed for volume

 Kubernetes Persistent Volume Claims (PVC) are used to abstract the underlying storage infrastructure, allowing developers to mount storage to a pod without knowing the details of the storage. However, sometimes the PVC may fail to mount, causing the applications to fail. In this article, we will discuss the steps to troubleshoot and resolve such issues.

Issue:

When trying to mount a PVC in a Kubernetes pod, the mount fails with the following error:

"MountVolume.SetUp failed for volume [volume name] : failed to fetch token: cannot get auth token"

Error:

The error message "MountVolume.SetUp failed for volume [volume name] : failed to fetch token: cannot get auth token" indicates that the pod was not able to authenticate to the storage provider and obtain the required credentials to mount the volume.

Resolution:

Follow the following steps to resolve the issue:

Step 1: Check the access mode set for the PVC in the persistent volume (PV) definition file.

The first step is to ensure that the access mode set for the PVC in the PV definition file matches the access mode required by the pod. For example, if the pod requires read-write access, but the PVC is set to read-only, the pod will fail to mount the PVC.

The access mode can be set to one of the following values:

ReadWriteOnce: Allows the volume to be mounted as read-write by a single node.

ReadOnlyMany: Allows the volume to be mounted as read-only by multiple nodes.

ReadWriteMany: Allows the volume to be mounted as read-write by many nodes.

Ensure that the access mode set for the PVC matches the access mode required by the pod.

Step 2: Check the credentials used to authenticate to the storage provider.

If the access mode is correct, check the credentials used to authenticate to the storage provider. Ensure that the credentials are correct and that the storage provider allows access from the Kubernetes cluster. If necessary, update the credentials or configure the storage provider to allow access from the Kubernetes cluster.

Here's an example YAML file defining a PVC with a secret object as the authentication method:

 apiVersion: v1  
 kind: PersistentVolumeClaim  
 metadata:  
  name: my-pvc  
 spec:  
  accessModes:  
   - ReadWriteOnce  
  resources:  
   requests:  
    storage: 1Gi  
  volumeMode: Filesystem  
  storageClassName: aws-ebs  
  volumeName: my-pv  
  volumeMode: Filesystem  
  dataSource:  
   kind: Secret  
   name: my-secret  

In this example, the PVC is using the "aws-ebs" storage class and the authentication is provided by a Kubernetes secret object named "my-secret". Ensure that the secret object contains the correct credentials to authenticate to the storage provider.

Step 3: Check the Storage Class used by the PVC

If the access mode and credentials are correct, check the Storage Class used by the PVC. Ensure that the Storage Class is correctly configured and supports the required access mode. If necessary, create a new Storage Class or update the existing one to support the required access mode.

Here's an example YAML file defining a Storage Class:

 apiVersion: storage.k8s.io/v1  
 kind: StorageClass  
 metadata:  
  name: fast  
 provisioner: kubernetes.io/aws-ebs  
 parameters:  
  type: gp2  
 reclaimPolicy: Retain  
 mountOptions:  
  - debug  

In this example, the Storage Class "fast" uses the provisioner "kubernetes.io/aws-ebs" to provision the storage, and supports the access mode "ReadWriteOnce". Ensure that the Storage Class used by the PVC is correctly configured