<p>I have an application running over a POD in Kubernetes.
I would like to store some output file logs on a persistent storage volume.</p>

<p>In order to do that, I created a volume over the NFS and bound it to the POD through the related volume claim.
When I try to write or accede the shared folder I got a "permission denied" message, since the NFS is apparently read-only.</p>

<p>The following is the json file I used to create the volume:</p>

<pre><code>{
      "kind": "PersistentVolume",
      "apiVersion": "v1",
      "metadata": {
        "name": "task-pv-test"
      },
      "spec": {
        "capacity": {
          "storage": "10Gi"
        },
        "nfs": {
          "server": &lt;IPAddress&gt;,
          "path": "/export"
        },
        "accessModes": [
          "ReadWriteMany"
        ],
        "persistentVolumeReclaimPolicy": "Delete",
        "storageClassName": "standard"
      }
    }
</code></pre>

<p>The following is the POD configuration file</p>

<pre><code>kind: Pod
apiVersion: v1
metadata:
    name: volume-test
spec:
    volumes:
        -   name: task-pv-test-storage
            persistentVolumeClaim:
                claimName: task-pv-test-claim
    containers:
        -   name: volume-test
            image: &lt;ImageName&gt;
            volumeMounts:
            -   mountPath: /home
                name: task-pv-test-storage
                readOnly: false
</code></pre>

<p>Is there a way to change permissions?</p>

<hr>

<p>UPDATE</p>

<p>Here are the PVC and NFS config:</p>

<p>PVC:</p>

<pre><code>kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: task-pv-test-claim
spec:
  storageClassName: standard
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 3Gi
</code></pre>

<p>NFS CONFIG</p>

<pre><code>{
  "kind": "Pod",
  "apiVersion": "v1",
  "metadata": {
    "name": "nfs-client-provisioner-557b575fbc-hkzfp",
    "generateName": "nfs-client-provisioner-557b575fbc-",
    "namespace": "default",
    "selfLink": "/api/v1/namespaces/default/pods/nfs-client-provisioner-557b575fbc-hkzfp",
    "uid": "918b1220-423a-11e8-8c62-8aaf7effe4a0",
    "resourceVersion": "27228",
    "creationTimestamp": "2018-04-17T12:26:35Z",
    "labels": {
      "app": "nfs-client-provisioner",
      "pod-template-hash": "1136131967"
    },
    "ownerReferences": [
      {
        "apiVersion": "extensions/v1beta1",
        "kind": "ReplicaSet",
        "name": "nfs-client-provisioner-557b575fbc",
        "uid": "3239b14a-4222-11e8-8c62-8aaf7effe4a0",
        "controller": true,
        "blockOwnerDeletion": true
      }
    ]
  },
  "spec": {
    "volumes": [
      {
        "name": "nfs-client-root",
        "nfs": {
          "server": &lt;IPAddress&gt;,
          "path": "/Kubernetes"
        }
      },
      {
        "name": "nfs-client-provisioner-token-fdd2c",
        "secret": {
          "secretName": "nfs-client-provisioner-token-fdd2c",
          "defaultMode": 420
        }
      }
    ],
    "containers": [
      {
        "name": "nfs-client-provisioner",
        "image": "quay.io/external_storage/nfs-client-provisioner:latest",
        "env": [
          {
            "name": "PROVISIONER_NAME",
            "value": "&lt;IPAddress&gt;/Kubernetes"
          },
          {
            "name": "NFS_SERVER",
            "value": &lt;IPAddress&gt;
          },
          {
            "name": "NFS_PATH",
            "value": "/Kubernetes"
          }
        ],
        "resources": {},
        "volumeMounts": [
          {
            "name": "nfs-client-root",
            "mountPath": "/persistentvolumes"
          },
          {
            "name": "nfs-client-provisioner-token-fdd2c",
            "readOnly": true,
            "mountPath": "/var/run/secrets/kubernetes.io/serviceaccount"
          }
        ],
        "terminationMessagePath": "/dev/termination-log",
        "terminationMessagePolicy": "File",
        "imagePullPolicy": "Always"
      }
    ],
    "restartPolicy": "Always",
    "terminationGracePeriodSeconds": 30,
    "dnsPolicy": "ClusterFirst",
    "serviceAccountName": "nfs-client-provisioner",
    "serviceAccount": "nfs-client-provisioner",
    "nodeName": "det-vkube-s02",
    "securityContext": {},
    "schedulerName": "default-scheduler",
    "tolerations": [
      {
        "key": "node.kubernetes.io/not-ready",
        "operator": "Exists",
        "effect": "NoExecute",
        "tolerationSeconds": 300
      },
      {
        "key": "node.kubernetes.io/unreachable",
        "operator": "Exists",
        "effect": "NoExecute",
        "tolerationSeconds": 300
      }
    ]
  },
  "status": {
    "phase": "Running",
    "hostIP": &lt;IPAddress&gt;,
    "podIP": "&lt;IPAddress&gt;,
    "startTime": "2018-04-17T12:26:35Z",
    "qosClass": "BestEffort"
  }
}
</code></pre>

<p>I have just removed some status information from the nfs config to make it shorter</p>

<p>If you set the proper <code>securityContext</code> for the pod configuration you can make sure the volume is mounted with proper permissions.</p>
<p>Example:</p>
<pre><code>apiVersion: v1
kind: Pod
metadata:
  name: demo
spec:
  securityContext:
    fsGroup: 2000 
  volumes:
    - name: task-pv-test-storage
      persistentVolumeClaim:
        claimName: task-pv-test-claim
  containers:
  - name: demo
    image: example-image
    volumeMounts:
    - name: task-pv-test-storage
      mountPath: /data/demo
</code></pre>
<p>In the above example the storage will be mounted at <code>/data/demo</code> with 2000 group id, which is set by <code>fsGroup</code>. By setting the fsGroup all processes of the container will also be part of the supplementary group ID 2000, thus you should have access to the mounted files.</p>
<p>You can read more about pod security context here: <a href="https://kubernetes.io/docs/tasks/configure-pod-container/security-context/" rel="noreferrer">https://kubernetes.io/docs/tasks/configure-pod-container/security-context/</a></p>
