Portworx with CSI

CSI, or Container Storage Interface, is a model for integrating storage system service with Kubernetes and other orchestration systems. Kubernetes has supported CSI since 1.10 as beta.

With CSI, Kubernetes gives storage drivers the opportunity to release on their schedule. This allows storage vendors to upgrade, update, and enhance their drivers without the need to update Kubernetes, maintaining a consistent, dependable, orchestration system.

Using Portworx with CSI, you can perform the following operations:

• Create and use CSI-enabled persistent volumes
• Secure your CSI-enabled volumes with token authorization and encryption defined at the StorageClass or the PVC level
• Take snapshots of CSI-enabled volumes
• Create shared CSI-enabled volumes

Supported features

The following table shows the features supported by the different versions of Kubernetes and Portworx:

Prerequisites

Before you install and use Portworx with CSI, ensure you meet the prerequisistes:

• Openshift users must use Openshift 4.1 or higher
• Kubernetes users must use 1.13 or higher

Install

Enable CSI during Portworx installation. You can do this in one of two ways:

• If you’re generating specs using the Portworx Kubernetes spec generator, generate the Portworx specs with the Portworx spec generator in PX-Central appropriate for your cluster. In the Customize tab, under Advanced Settings, select CSI. This will add the CSI components to the Portworx DaemonSet.

• If you are using cURL to fetch the Portworx spec, add csi=true to the parameter list to include CSI specs in the generated file.

oc adm policy add-scc-to-user privileged system:serviceaccount:kube-system:px-csi-account

Create and use persistent volumes

To enable CSI for a StorageClass, set the provisioner value to pxd.portworx.com:

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: portworx-csi-sc
provisioner: pxd.portworx.com
parameters:
  repl: "1"

To create a PersistentVolumeClaim based on your CSI-enabled StorageClass, reference the StorageClass you created above with the storageClassName parameter:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
   name: px-mysql-pvc
spec:
   storageClassName: portworx-csi-sc
   accessModes:
     - ReadWriteOnce
   resources:
     requests:
       storage: 2Gi

Once you’ve created a storage class and PVC, you can create a volume as part of a deployment by referencing the PVC. This example creates a MySQL deployment referencing the px-mysql-pvc PVC you created in the step above:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
    type: RollingUpdate
  replicas: 1
  template:
    metadata:
      labels:
        app: mysql
        version: "1"
    spec:
      containers:
      - image: mysql:5.6
        name: mysql
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: password
        ports:
        - containerPort: 3306
        volumeMounts:
        - name: mysql-persistent-storage
          mountPath: /var/lib/mysql
      volumes:
      - name: mysql-persistent-storage
        persistentVolumeClaim:
          claimName: px-mysql-pvc

Secure your volumes

You can secure your CSI-enabled volumes with token-based authorization. In using token-based authorization, you create secrets containing your token credentials and specify them in your StorageClass in one of two ways:

• Using hardcoded values
• Using template values

You can also mix these two methods to form your own hybrid approach.

Using hardcoded values

This example secures a storage class by specifying hardcoded values for the token and namespace. Users who create PVCs based on this StorageClass will always have their PVCs use the px-secret StorageClass under the portworx namespace.

1. enter the kubectl create secret command to create a token:

   kubectl create secret generic px-secret -n portworx --from-literal=auth-token=$token

2. Modify the storageClass, adding the following parameters:

   kind: StorageClass
   apiVersion: storage.k8s.io/v1
   metadata:
     name: portworx-csi-sc
   provisioner: pxd.portworx.com
   parameters:
     repl: "1"
     csi.storage.k8s.io/provisioner-secret-name: px-secret
     csi.storage.k8s.io/provisioner-secret-namespace: portworx
     csi.storage.k8s.io/node-publish-secret-name: px-secret
     csi.storage.k8s.io/node-publish-secret-namespace: portworx

Using template values

This example secures a storage class by hardcoding the token and namespace. Users who create PVCs based on this StorageClass can have have their PVCs use the StorageClass they specified in the annotation of their PVC, and the namespace they specified in their PVC.

1. Modify the storageClass, adding the following parameters:

   • csi.storage.k8s.io/provisioner-secret-name: ${pvc.name}
   • csi.storage.k8s.io/provisioner-secret-namespace: ${pvc.namespace}
   • csi.storage.k8s.io/node-publish-secret-name: ${pvc.name}
   • csi.storage.k8s.io/node-publish-secret-namespace: ${pvc.namespace}

   kind: StorageClass
   apiVersion: storage.k8s.io/v1
   metadata:
     name: portworx-csi-sc
   provisioner: pxd.portworx.com
   parameters:
     repl: "1"
     csi.storage.k8s.io/provisioner-secret-name: ${pvc.name}
     csi.storage.k8s.io/provisioner-secret-namespace: ${pvc.namespace}
     csi.storage.k8s.io/node-publish-secret-name: ${pvc.name}
     csi.storage.k8s.io/node-publish-secret-namespace: ${pvc.namespace}

2. Make sure your user also creates a secret in their PVC’s namespace with the same name as the PVC. For example, a PVC named “px-mysql-pvc” must have an associated secret named “px-mysql-pvc”. Enter the following command to create the secret:

   kubectl create secret generic px-mysql-pvc -n portworx --from-literal=auth-token=$token

Take snapshots of CSI-enabled volumes

For Kubernetes 1.17+, CSI Snapshotting is in beta is supported by the Portworx CSI Driver.

Given you already have a CSI PVC and StorageClass, complete the following steps to create and restore a CSI VolumeSnapshot.

1. Create a VolumeSnapshotClass, specifying the following:

   • The snapshot.storage.kubernetes.io/is-default-class: "true" annotation
   • The csi.storage.k8s.io/snapshotter-secret-name parameter with your encryption and/or authorization secret
   • The csi.storage.k8s.io/snapshotter-secret-namespace parameter with the namespace your secret is in

     apiVersion: snapshot.storage.k8s.io/v1beta1
     kind: VolumeSnapshotClass
     metadata:
       name: px-csi-snapclass
       annotations:
         snapshot.storage.kubernetes.io/is-default-class: "true"
     driver: pxd.portworx.com
     deletionPolicy: Delete
     parameters:
       csi.storage.k8s.io/snapshotter-secret-name: px-secret
       csi.storage.k8s.io/snapshotter-secret-namespace: portworx

2. Create a VolumeSnapshot:

     apiVersion: snapshot.storage.k8s.io/v1beta1
     kind: VolumeSnapshot
     metadata:
       name: px-csi-snapshot
     spec:
       volumeSnapshotClassName: px-csi-snapclass
       source:
         persistentVolumeClaimName: px-mysql-pvc

3. Restore from a VolumeSnapshot:

     apiVersion: v1
     kind: PersistentVolumeClaim
     metadata:
       name: px-csi-pvc-restored 
     spec:
       storageClassName: portworx-csi-sc
       dataSource:
         name: px-csi-snapshot
         kind: VolumeSnapshot
         apiGroup: snapshot.storage.k8s.io
       accessModes:
         - ReadWriteOnce
       resources:
         requests:
           storage: 1Gi

See the Kubernetes-CSI snapshotting documentation for more examples and documentation.

Snapshotting alpha

CSI volume snapshotting is alpha from Kubernetes 1.12 until 1.16. In order to take snapshots of CSI-enabled volumes for these versions, you must enable the VolumeSnapshotDataSource feature gate:

  --feature-gates=VolumeSnapshotDataSource=true

In addition, you must use a 1.x release of the external snapshotter that will create and understand the nessesary alpha APIs.

Create shared CSI-enabled volumes

You can create shared CSI-enabled volumes using one of two methods:

• Using a PVC’s AccessMode parameter
• Using StorageClass parameters

PVC AccessMode

In your PVC, if you use ReadWriteMany, Portworx defaults to a Sharedv4 volume type.

StorageClass parameters

• In your SC, if you use the parameter Shared=true and ReadWriteMany in your PVC, Portworx uses the Shared volume type.
• In your SC, if you use the parameter Sharedv4=true and ReadWriteMany in your PVC, Portworx uses the Sharedv4 volume type.

Encryption with CSI

For information about how to encrypt PVCs on CSI using Kubernetes secrets, see the Encrypting PVCs on CSI with Kubernetes Secrets section of the Portworx documentation.

Upgrade

Currently upgrades are not supported. You will need to deploy using CSI onto a new Kubernetes cluster. The Kubernetes community is working very hard to make this possible in the near future.

Contribute

Portworx, Inc. welcomes contributions to its CSI implementation, which is open-source and repository is at OpenStorage.