title: Kubernetes mount volume on existing directory with files inside the container
body: <p>I am using k8s with version 1.11 and CephFS as storage.</p>
  
  <p>I am trying to mount the directory created on the CephFS in the pod. To achieve the same I have written the following volume and volume mount config
  in the deployment configuration</p>
  
  <p>Volume</p>
  
  <pre><code>{
    "name": "cephfs-0",
    "cephfs": {
      "monitors": [
        "10.0.1.165:6789",
        "10.0.1.103:6789",
        "10.0.1.222:6789"
      ],
      "user": "cfs",
      "secretRef": {
        "name": "ceph-secret"
      },
      "readOnly": false,
      "path": "/cfs/data/conf"
    }
  }
  </code></pre>
  
  <p>volumeMounts</p>
  
  <pre><code>{
    "mountPath": "/opt/myapplication/conf",
    "name": "cephfs-0",
    "readOnly": false
  } 
  </code></pre>
  
  <p>Mount is working properly. I can see the ceph directory i.e. /cfs/data/conf getting mounted on  /opt/myapplication/conf but following is my issue.</p>
  
  <p>I have configuration files already present as a part of docker image at the location /opt/myapplication/conf. When deployment tries to mount the ceph volume then all the files at the location /opt/myapplication/conf gets disappear. I know it's the behavior of the mount operation but is there any way by which I would be able to persist the already existing files in the container on the volume which I am mounting so that other pod which is mounting the same volume can access the configuration files. i.e. the files which are already there inside the pod at the location /opt/myapplication/conf should be accessible on the CephFS at location /cfs/data/conf.</p>
  
  <p>Is it possible?</p>
  
  <p>I went through the docker document and it mentions that </p>
  
  <blockquote>
    <p>Populate a volume using a container
    If you start a container which creates a new volume, as above, and the container has files or directories in the directory to be mounted (such as /app/ above), the directory’s contents are copied into the volume. The container then mounts and uses the volume, and other containers which use the volume also have access to the pre-populated content.</p>
  </blockquote>
  
  <p>This matches with my requirement but how to achieve it with k8s volumes?</p>