Example: Mounting a PersistentVolume for Dynamic Provisioning Using MapR Container Storage Interface (CSI) Storage Plugin

This example also uses a PersistentVolume. However, unlike the previous example, when you use the MapR dynamic provisioner, you do not need to create a PersistentVolume manually. The PersistentVolume is created automatically based on the parameters specified in the referenced StorageClass.

Dynamic provisioning is useful in cases where you do not want MapR and Kubernetes administrators to create storage manually to store the Pod storage state.

The following example uses a PersistentVolumeClaim that references a Storage Class. In this example, a Kubernetes Administrator has created a storage class called test-secure-sc for Pod creators to use when they want to create persistent storage for their Pods. In this example, it is important for the created Pod storage to survive the deletion of a Pod.

To dynamically provision a volume, you must do the following:

Generate a MapR service ticket and create and deploy a ticket secret on the Pod.
See maprlogin for information on generating a ticket and Configuring a Secret for information on creating and deploying a ticket secret.
Create the REST secret and deploy the secret on the Pod.
See Configuring a Secret for information on creating and deploying a ticket secret.

Create a StorageClass similar to the following:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: test-secure-sc
  namespace: test-csi
provisioner: com.mapr.csi-kdf
parameters:
    csiProvisionerSecretName: "mapr-provisioner-secrets"
    csiProvisionerSecretNamespace: "test-csi"
    csiNodePublishSecretName: "mapr-ticket-secret"
    csiNodePublishSecretNamespace: "test-csi"
    restServers: "10.10.10.210:8443"
    cldbHosts: "10.10.10.210:7222"
    cluster: "clusterA"
    securityType: "secure"
    namePrefix: "csi-pv"
    mountPrefix: "/csi"
    advisoryquota: "100M"

For more information, see Storage Classes. The following table shows the properties defined in the sample StorageClass:

Property	Description
`apiVersion`	The Kubernetes APi version for the StorageClass spec.
`kind`	The kind of object being created. This is a StorageClass.
`metadata: name`	The name of the StorageClass. Administrators should specify the name carefully because it will be used by Pod authors to help select the right StorageClass for their needs.
`metadata: namespace`	The namespace in which the StorageClass runs. This namespace can be different from the namespace used by the PVC and Pod, since the StorageClass namespace can be a cross-namespace resource.
`provisioner`	The provisioner being used. for the MapR provisioner, specify `mapr.com/maprfs`.
`csiNodePublishSecretName`	The name of the Secret that contains the ticket to use when mounting to the MapR cluster. See Configuring a Secret.
`csiNodePublishSecretNamespace`	The namespace that contains the Secret. Use the same namespace as the namespace used by the Pod.
`csiProvisionerSecretName` (deprecated) `csi.storage.k8s.io/provisioner-secret-name`	The name of the Kubernetes Secret that is used to store MapR administrative credentials (user, password, and ticket information for the MapR webserver). To use the provisioner, you must configure a Secret. See Configuring a Secret.
`csiProvisionerSecretNamespace` (deprecated) `csi.storage.k8s.io/provisioner-secret-namespace`	The namespace for the Secret containing the MapR administrative credentials (user name and password information for a MapR user that has the privileges to create MapR volumes). This namespace can be different from the namespace used by the Pod, since a Pod author or namespace admin might not be trusted to create administration Secrets for the MapR cluster.
`restServers`	A space-separated list of MapR webservers. Specify the hostname or IP address and port number of each REST server for the MapR cluster. For fault tolerance, providing multiple REST server hosts is recommended.
`cldbHosts`	The hostname or IP addresses of the CLDB hosts for the MapR cluster. You must provide at least one CLDB host. For fault-tolerance, providing multiple CLDB hosts is recommended. To specify multiple hosts, separate each name or IP address by a space.
`cluster`	The MapR cluster name.
`securityType`	A parameter that indicates whether MapR tickets are used or not used. If MapR tickets are used, specify `secure`. Otherwise, specify `unsecure`.
`namePrefix`	A prefix for the MapR volume to be created. For example, if you specify `PV` as the `namePrefix`, the first dynamically created volume might be named `PV.bevefsescr`. The provisioner generates random names using lower-case letters. If you do not specify a prefix, the provisioner uses `maprprovisioner` as a prefix.
`mountPrefix`	The parent path of the mount in MapR file system. If you do not specify a mount prefix, the provisioner mounts your volume under the MapR root.
`advisoryquota`	The advisory storage quota for the MapR volume. The `advisoryquota` is one of the MapR parameters that you can specify for dynamic provisioning. For more information, see Before You Begin.

Configure a PersistentVolumeClaim similar to the following:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: test-secure-pvc
  namespace: test-csi
spec:
  storageClassName: test-secure-sc
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5G

The following table shows the properties defined in the sample PersistentVolumeClaim:

Property	Description
`apiVersion`	The Kubernetes API version for the Pod spec.
`kind`	The kind of object being created. This is a PersistentVolumeClaim (PVC).
`metadata: name`	The PVC name.
`metadata: namespace`	The namespace in which the PVC runs. This should be the same namespace used by the Pod.
`storageClassName`	The name of the storage class requested by the PersistentVolumeClaim. For more information, see Dynamic Provisioning and Storage Classes.
`accessModes`	How the PersistentVolume is mounted on the host. For more information, see Access Modes.
`requests: storage`	The storage resources being requested, or that were requested and have been allocated. The Pod author can use this parameter to tell MapR how much quota is needed for the MapR volume. For the units, see Resource Model.

Create the Pod spec similar to the following:

apiVersion: v1
kind: Pod
metadata:
  name: test-secure-pod
  namespace: test-csi
spec:
  containers:
  - name: busybox
    image: busybox
    args:
    - sleep
    - "1000000"
    resources:
      requests:
        memory: "2Gi"
        cpu: "500m"
    volumeMounts:
    - mountPath: /mapr
      name: maprflex
  volumes:
    - name: maprflex
      persistentVolumeClaim:
        claimName: test-secure-pvc

The following table shows the properties defined in the sample Pod spec:

Property	Description
`apiVersion`	The Kubernetes API version for the Pod spec.
`kind`	The kind of object being created. For clarity, this example uses a naked Pod. Generally, it is better to use a Deployment, DaemonSet, or StatefulSet for high availability and ease of upgrade.
`metadata: name`	The Pod name.
`metadata: namespace`	The namespace in which the Pod runs. It should be the same namespace in which the PVC runs.
`volumeMounts: mountPath`	A directory inside the container that is designated as the mount path.
`volumeMounts: name`	A name that you assign to the Kubernetes `volumeMounts` resource. The value should match `Volumes: name`.
`Volumes: name`	A string to identify the name of the Kubernetes `volumes` resource. The value should match `volumeMounts: name`.
`persistentVolumeClaim: claimName`	The name of the PersistentVolumeClaim (PVC). For more information, see PersistentVolumeClaims.

Deploy the .yaml file on the pod by running the following command:

kubectl apply -f <filename>.yaml

For each Pod mount request, the POSIX client starts with the Pod's hostname and new generated hostid, which is tracked on the MapR cluster. You can run the node list command on the MapR cluster to determine the number of POSIX clients. For example:

# maprcli node list -clientsonly true
clienttype clienthealth hostname ip lasthb id
posixclientbasic Inactive 4f3d34fe-2007-11e9-8980-0cc47ab39644 10.10.102.94,172.17.0.1,192.168.28.0 11225 7407394893618656436
posixclientbasic Inactive 7906d011-200f-11e9-84c0-0cc47ab39644 10.10.102.94,172.17.0.1,192.168.28.0 8174 7544602061076655421
posixclientbasic Inactive 9ed61912-2004-11e9-8980-0cc47ab39644 10.10.102.92,172.17.0.1,192.168.184.128 11224 2540810767207593086
posixclientbasic Inactive c35ab639-2010-11e9-84c0-0cc47ab39644 10.10.102.94,172.17.0.1,192.168.28.0 7568 7947067275504513691
posixclientbasic Active e5dc10e8-2012-11e9-84c0-0cc47ab39644 10.10.102.94,172.17.0.1,192.168.28.0 18 5849529086453778130

Full example, which includes PV, PVC, and Pod configuration

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: test-secure-sc
  namespace: test-csi
provisioner: com.mapr.csi-kdf
parameters:
    csiProvisionerSecretName: "mapr-provisioner-secrets"
    csiProvisionerSecretNamespace: "test-csi"
    csiNodePublishSecretName: "mapr-ticket-secret"
    csiNodePublishSecretNamespace: "test-csi"
    restServers: "10.10.10.210"
    cldbHosts: "10.10.10.210"
    cluster: "clusterA"
    securityType: "secure"
    namePrefix: "csi-pv"
    mountPrefix: "/csi"
    advisoryquota: "100M"
--
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: test-secure-pvc
  namespace: test-csi
spec:
  storageClassName: test-secure-sc
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5G
--
apiVersion: v1
kind: Pod
metadata:
  name: test-secure-pod
  namespace: test-csi
spec:
  containers:
  - name: busybox
    image: busybox
    args:
    - sleep
    - "1000000"
    resources:
      requests:
        memory: "2Gi"
        cpu: "500m"
    volumeMounts:
    - mountPath: /mapr
      name: maprflex
  volumes:
    - name: maprflex
      persistentVolumeClaim:
        claimName: test-secure-pvc