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Pivotal Container Service v1.2

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Configuring PersistentVolumes

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This topic describes how to provision static and dynamic PersistentVolumes (PVs) for Pivotal Container Service (PKS) to run stateful apps.

For more information about the supported vSphere topologies for PV storage, see vSphere PersistentVolume Storage Options on vSphere.

For static PV provisioning, you do not need to specify a StorageClass. The PersistentVolumeClaim (PVC) does not need to reference a StorageClass. For dynamic PV provisioning, you must specify a StorageClass and define the PVC using a reference to that StorageClass.

Provision a Static PV

To provision a static PV, you manually create a Virtual Machine Disk (VMDK) file to use as a storage backend for the PV. When the PV is created, Kubernetes knows which volume instance is ready for use. When a PVC or volumeClaimTemplate is requested, Kubernetes chooses an available PV in the system and allocates it to the Deployment or StatefulSets workload.

Provision a Static PV for a Deployment Workload

To provision a static PV for a Deployment workload, the procedure is as follows:

1. Create VMDK files, replacing DATASTORE with your datastore directory name:

   [root@ESXi-1:~] cd /vmfs
   [root@ESXi-1:/vmfs] cd volumes/
   [root@ESXi-1:/vmfs/volumes] cd DATASTORE/
   [root@ESXi-1:/vmfs/volumes/DATASTORE] cd kubevols/
   [root@ESXi-1:/vmfs/volumes/DATASTORE/kubevols] vmkfstools -c 2G redis-master.vmdk
   

2. Define a PV using a YAML manifest file that contains a reference to the VMDK file. For example, create a file named redis-master-pv.yaml with the following contents:

   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: redis-master-pv
   spec:
     capacity:
       storage: 2Gi
     accessModes:
       - ReadWriteOnce
     persistentVolumeReclaimPolicy: Retain
     vsphereVolume:
       volumePath: "[DATASTORE] kubevols/redis-master"
       fsType: ext4
   

3. Define a PVC using a YAML manifest file. For example, create a file named redis-master-claim.yaml with the following contents:

   kind: PersistentVolumeClaim
   apiVersion: v1
   metadata:
     name: redis-master-claim
   spec:
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
       storage: 2Gi
   

4. Define a deployment using a YAML manifest file that references the PVC. For example, create a file named redis-master.yaml with the following contents:

   apiVersion: extensions/v1beta1
   kind: Deployment
   metadata:
     name: redis-master
   …
   spec:
     template:
       spec:
         volumes:
         - name: redis-master-data
         persistentVolumeClaim:
           claimName: redis-master-claim
   

Provision a Static PV for a StatefulSets Workload

To provision a static PV for a StatefulSets workload with three replicas, the procedure is as follows:

1. Create VMDK files, replacing DATASTORE with your datastore directory name:

   [root@ESXi-1:~] cd /vmfs
   [root@ESXi-1:/vmfs] cd volumes/
   [root@ESXi-1:/vmfs/volumes] cd DATASTORE/
   [root@ESXi-1:/vmfs/volumes/DATASTORE] cd kubevols/
   [root@ESXi-1:/vmfs/volumes/DATASTORE/kubevols] vmkfstools -c 10G mysql-pv-1.vmdk
   [root@ESXi-1:/vmfs/volumes/DATASTORE/kubevols] vmkfstools -c 10G mysql-pv-2.vmdk
   [root@ESXi-1:/vmfs/volumes/DATASTORE/kubevols] vmkfstools -c 10G mysql-pv-3.vmdk
   

2. Define a PV for the first replica using a YAML manifest file that contains a reference to the VMDK file. For example, create a file named mysql-pv-1.yaml with the following contents:

   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: mysql-pv-1
   spec:
     capacity:
       storage: 10Gi
     accessModes:
       - ReadWriteOnce
     persistentVolumeReclaimPolicy: Retain
     vsphereVolume:
       volumePath: "[DATASTORE] kubevols/mysql-pv-1"
       fsType: ext4
   

3. Define a PV for the second replica using a YAML manifest file that contains a reference to the VMDK file. For example, create a file named mysql-pv-2.yaml with the following contents:

   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: mysql-pv-2
   spec:
     capacity:
       storage: 10Gi
     accessModes:
       - ReadWriteOnce
     persistentVolumeReclaimPolicy: Retain
     vsphereVolume:
       volumePath: "[DATASTORE] kubevols/mysql-pv-2"
       fsType: ext4
   

4. Define a PV for the third replica using a YAML manifest file that contains a reference to the VMDK file. For example, create a file named mysql-pv-3.yaml with the following contents:

   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: mysql-pv-3
   spec:
     capacity:
       storage: 10Gi
     accessModes:
       - ReadWriteOnce
     persistentVolumeReclaimPolicy: Retain
     vsphereVolume:
       volumePath: "[DATASTORE] kubevols/mysql-pv-3"
       fsType: ext4
   

5. Define a StatefultSets object using a YAML manifest file. For example, create a file named mysql-statefulsets.yaml with the following contents:

   piVersion: apps/v1
   kind: StatefulSet
   metadata:
     name: mysql
   spec:
     selector:
       matchLabels:
         app: mysql
     serviceName: mysql
     replicas: 3
   ...
   volumeClaimTemplates:
     - metadata:
       name: data
       spec:
       accessModes: ["ReadWriteOnce"]
       resources:
           requests:
           storage: 10Gi
   

   Note: In previous steps you created a total of three PVs. The spec.replicas: 3 field defines three replicas. Each replica is attached to one PV.

   Note: In the volumeClaimTemplates section, you must specify the required storage size for each replica. Do not to refer to a StorageClass.

Provision a Dynamic PV

For dynamic PV provisioning, the procedure is to define and create a PVC that automatically triggers the creation of the PV and its backend VMDK file. When the PV is created, Kubernetes knows which volume instance is available for use. When a PVC or volumeClaimTemplate is requested, Kubernetes chooses an available PV and allocates it to the Deployment or StatefulSets workload.

For usage instructions, see Using Dynamic PersistentVolumes.

Provision a Dynamic PV for Deployment Workloads

For the Deployment workload with dynamic PV provisioning, the procedure is as follows:

1. Define a StorageClass using a YAML manifest file. For example, create a file named redis-sc.yaml with the following contents:

   kind: StorageClass
   apiVersion: storage.k8s.io/v1
   metadata:
     name: thin-disk
   provisioner: kubernetes.io/vsphere-volume
   parameters:
       datastore: Datastore-NFS-VM
       diskformat: thin
       fstype: ext3
   

2. Define a PVC using a YAML manifest file that references the StorageClass. For example, create a file named redis-master-claim.yaml with the following contents:

   kind: PersistentVolumeClaim
   apiVersion: v1
   metadata:
     name: redis-master-claim
     annotations:
       volume.beta.kubernetes.io/storage-class: thin-disk
   spec:
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
       storage: 2Gi
   

   Note: When you deploy the PVC, the vSphere Cloud Provider plugin automatically creates the PV and associated VMDK file.

3. Define a Deployment using a YAML manifest file that references the PVC. For example, create a file named redis-master.yaml with the following contents:

   apiVersion: extensions/v1beta1
   kind: Deployment
   metadata:
     name: redis-master
   …
   spec:
     template:
       spec:
         volumes:
         - name: redis-master-data
           persistentVolumeClaim:
           claimName: redis-master-claim
   

Provision a Dynamic PV for StatefulSets Workloads

To provision a static PV for a StatefulSets workload with three replicas, the procedure is as follows:

1. Define a StorageClass using a YAML manifest file. For example, create a file named mysql-sc.yaml with the following contents:

   kind: StorageClass
   apiVersion: storage.k8s.io/v1
   metadata:
     name: my-storage-class
   provisioner: kubernetes.io/vsphere-volume
   parameters:
       datastore: Datastore-NFS-VM
       diskformat: thin
       fstype: ext3
   

2. Define a StatefultSets object using a YAML manifest file that references the StorageClass. For example, create a file named mysql-statefulsets.yaml with the following contents:

   apiVersion: apps/v1
   kind: StatefulSet
   metadata:
     name: mysql
   spec:
   ...
   volumeClaimTemplates:
     - metadata:
       name: data
       spec:
       accessModes: ["ReadWriteOnce"]
         storageClassName: "my-storage-class"
       resources:
           requests:
           storage: 10Gi
   

   Note: In the volumeClaimTemplates, specify the required storage size for each replica. Unlike static provisioning, you must explicitly refer to the desired StorageClass when you use dynamic PV provisioning.