Documentation

    PLEASE NOTE: This document applies to an unreleased version of Rook. It is strongly recommended that you only use official releases of Rook, as unreleased versions are subject to changes and incompatibilities that will not be supported in the official releases.

    If you are using an official release version of Rook, you should refer to the documentation for your specific version.

    Documentation for other releases can be found by using the version selector in the bottom left of any doc page.

    Ceph CSI Drivers

    There are two CSI drivers integrated with Rook that will enable different scenarios:

    • RBD: This driver is optimized for RWO pod access where only one pod may access the storage
    • CephFS: This driver allows for RWX with one or more pods accessing the same storage

    The drivers are enabled automatically with the Rook operator. They will be started in the same namespace as the operator when the first CephCluster CR is created.

    For documentation on consuming the storage:

    The remainder of this topic is on the snapshotting feature of the RBD driver.

    RBD Snapshots

    Since this feature is still in alpha stage (k8s 1.12+), make sure to enable the VolumeSnapshotDataSource feature gate on your Kubernetes cluster API server.

    --feature-gates=VolumeSnapshotDataSource=true
    

    SnapshotClass

    You need to create the SnapshotClass. The purpose of a SnapshotClass is defined in the kubernetes documentation. In short, as the documentation describes it:

    Just like StorageClass provides a way for administrators to describe the “classes” of storage they offer when provisioning a volume, VolumeSnapshotClass provides a way to describe the “classes” of storage when provisioning a volume snapshot.

    In snapshotClass, the csi.storage.k8s.io/snapshotter-secret-name parameter should reference the name of the secret created for the rbdplugin and pool to reflect the Ceph pool name.

    Update the value of the clusterID field to match the namespace that rook is running in. When Ceph CSI is deployed by Rook, the operator will automatically maintain a config map whose contents will match this key. By default this is “rook-ceph”.

    kubectl create -f cluster/examples/kubernetes/ceph/csi/rbd/snapshotclass.yaml
    

    Volumesnapshot

    In snapshot, snapshotClassName should be the name of the VolumeSnapshotClass previously created. The source name should be the name of the PVC you created earlier.

    kubectl create -f cluster/examples/kubernetes/ceph/csi/rbd/snapshot.yaml
    

    Verify RBD Snapshot Creation

    $ kubectl get volumesnapshotclass
    NAME                      AGE
    csi-rbdplugin-snapclass   4s
    $ kubectl get volumesnapshot
    NAME               AGE
    rbd-pvc-snapshot   6s
    

    In the toolbox pod, run rbd snap ls [name-of-your-pvc]. The output should be similar to this:

    $ rbd snap ls pvc-c20495c0d5de11e8
    SNAPID NAME                                                                      SIZE TIMESTAMP
         4 csi-rbd-pvc-c20495c0d5de11e8-snap-4c0b455b-d5fe-11e8-bebb-525400123456 1024 MB Mon Oct 22 13:28:03 2018
    

    Restore the snapshot to a new PVC

    In pvc-restore, dataSource should be the name of the VolumeSnapshot previously created. The kind should be the VolumeSnapshot.

    Create a new PVC from the snapshot

    kubectl create -f cluster/examples/kubernetes/ceph/csi/rbd/pvc-restore.yaml
    

    Verify RBD Clone PVC Creation

    $ kubectl get pvc
    NAME              STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
    rbd-pvc           Bound    pvc-84294e34-577a-11e9-b34f-525400581048   1Gi        RWO            csi-rbd        34m
    rbd-pvc-restore   Bound    pvc-575537bf-577f-11e9-b34f-525400581048   1Gi        RWO            csi-rbd        8s
    

    RBD resource Cleanup

    To clean your cluster of the resources created by this example, run the following:

    if you have tested snapshot, delete snapshotclass, snapshot and pvc-restore created to test snapshot feature

    kubectl delete -f cluster/examples/kubernetes/ceph/csi/rbd/pvc-restore.yaml
    kubectl delete -f cluster/examples/kubernetes/ceph/csi/rbd/snapshot.yaml
    kubectl delete -f cluster/examples/kubernetes/ceph/csi/rbd/snapshotclass.yaml
    

    Liveness Sidecar

    All CSI pods are deployed with a sidecar container that provides a prometheus metric for tracking if the CSI plugin is alive and runnning. These metrics are meant to be collected by prometheus but can be acceses through a GET request to a specific node ip. for example curl -X get http://[pod ip]:[liveness-port][liveness-path] 2>/dev/null | grep csi the expected output should be

    $ curl -X GET http://10.109.65.142:9080/metrics 2>/dev/null | grep csi
    # HELP csi_liveness Liveness Probe
    # TYPE csi_liveness gauge
    csi_liveness 1
    

    Check the monitoring doc to see how to integrate CSI liveness and grpc metrics into ceph monitoring.