Standalone kubelet persistent disk mount on Google Cloud instance

I have a process that needs to run daily in a Docker container, syncing some data from a storage bucket to an external volume (Google Cloud persistent disk). So far, I managed to launch the process by creating a single-node container cluster.

Since the process completes in a couple of hours, I want to delete VM resources (except the persistent disk of course) once complete. Launching/deleting a single compute-VM (without the kubernetes cluster setup) seems simpler, so I was trying to get a single kubelet running on a container-optimized cloud instance. Persistent disk mounting is where this fails.

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  • My launch command:

    gcloud compute instances create cvm-name-0 \
        --image-family=cos-stable \
        --image-project=cos-cloud \
        --boot-disk-type pd-ssd \
        --boot-disk-size 10GB \
        --metadata-from-file \
        "google-container-manifest=containers.yaml,user-data=cloudinit.yaml" \
        --zone "$gzone" \
        --scopes default,storage-rw \
        --machine-type n1-highcpu-4
    

    Contents of container.yaml:

    apiVersion: v1
    kind: Pod
    metadata:
      name: container-name
    spec:
      containers:
        - name: container-name
          image: gcr.io/project-name/container-name
          imagePullPolicy: Always
          volumeMounts:
            - name: persistent-disk-name
              mountPath: /home/someuser/somedir
      volumes:
        - name: persistent-disk-name
          gcePersistentDisk:
            pdName: persistent-disk-name
            fsType: ext4
    

    Contents of cloudinit.yaml:

    #cloud-config
    bootcmd:
    - echo "KUBELET_OPTS=\"--cloud-provider=gce\"" > /etc/default/kubelet
    runcmd:
    - systemctl start kubelet.service
    

    While the --cloud-provider=gce option fixes the “Failed to get GCE Cloud Provider” error per this question, there is still some problem mounting the disk.

    A potentially relevant line from the container OS log says:

    EXT4-fs (dm-0): couldn’t mount as ext3 due to feature incompatibilities

    Any way to make this work on a single compute instance (without the kubernetes cluster)? Where else should I be looking for more informative error logs?

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  • One Solution collect form web for “Standalone kubelet persistent disk mount on Google Cloud instance”

    I’m not using kubernetes at the moment, but I am backing up to a cloud storage bucket.

    I have something like this in my cloud-config:

    users:
    - name: dockerrunner
      uid: 2000
      groups: docker
    write_files:
    - path: /home/dockerrunner/backup-hourly.sh
      permissions: 0755
      owner: dockerrunner
      content: |
        #!/bin/sh
        export HOME=/home/dockerrunner
        export USER=root
        toolbox --bind /mnt/disks/nfs:/mnt/disks/nfs \
          /google-cloud-sdk/bin/gsutil -m \
          rsync -r /mnt/disks/nfs gs://<bucket-name>/hourly
    - path: /etc/systemd/system/files-backup-hourly.service
      permissions: 0644
      owner: root
      content: |
        [Unit]
        Description=Shared Files Backup upload script - hourly
    
        [Service]
        Type=oneshot
        ExecStart=/bin/sh /home/dockerrunner/backup-hourly.sh
    
    - path: /etc/systemd/system/files-backup-hourly.timer
      permissions: 0644
      owner: root
      content: |
        [Unit]
        Description=Run Shared Files Backup create script every hour
    
        [Timer]
        OnCalendar=*-*-* *:00:00
    
        [Install]
        WantedBy=timers.target
    runcmd:
    - systemctl daemon-reload
    - systemctl start files-backup-hourly.service
    - systemctl start files-backup-hourly.timer
    
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