Kubernetes CSI features with Pure service orchestrator

The Pure Service Orchestrator 5.2.0 release now supports the kubernetes container storage interface 1.2.0 specification (in addition to 1.0.and 1.1). It brings new and exciting functionality: volume resize, snapshot and import amongst others.

For those or you asking ‘what is the pure service orchestrator’ refer to this blog to find out more.

In this article, I will go over an automated ansible script that showcases the pure storage service orchestrators integration with these CSI capabilities.

The ansible code can be found on my gitlab site here:

• ansible playbook for Flasharray based demo
• ansible playbook for Flashblade based demo

The playbook requires a kubernetes cluster, in this example I will be using a one node master/worker. This k8s cluster has iSCSI access to a Flasharray and NFS access to a Flashblade as well as the latest 5.2.0 pure storage orchestrator installed and configured for both storage platforms. In this run of the demo we will be using the Flasharray.

The ansible playbook starts by requesting information about the target kubernetes cluster (ip and sudo password) and based on that it creates a host entry that is used in the main demo section. This makes the playbook more portable as it does not rely on a hardcoded hosts definition file but one that is created during its execution.

This is accomplished using the below ansible task:

tasks:
 — name: add_host
   add_host:
     hostname: “{{ k8s_node }}”
     groups: k8s_target

The playbook proceeds with a few verification steps such as validating the pure service orchestrator version or iSCSI / NFS connectivity.

It creates a volume with some data and a snapshot leveraging the purestorage ansible modules, this is all done at the host layer so no kubernetes yet. The playbook will be using this snapshot of our physical hosts volume as the source to be imported into kubernetes. Here is the preliminary step in action:

Now for some kubernetes and the CSI features I mentioned:

1. Import of an existing volume

To import our ‘existing’ volume I use the following persistent volume and persistent volume claim definitions, (ansible variables replaced):

apiVersion: v1
kind: PersistentVolume
metadata:
  annotations:
    pv.kubernetes.io/provisioned-by: pure-csi
  name: volume-2-import-k8s-pv
spec:
  accessModes:
  - ReadWriteOnce
  capacity:
    storage: 4Gi
  claimRef:
    apiVersion: v1
    kind: PersistentVolumeClaim
    name: volume-2-import-k8s-pvc
    namespace: default
  csi:
    driver: pure-csi
    volumeHandle: volume-2-import
    volumeAttributes:
      backend: block
persistentVolumeReclaimPolicy: Delete
storageClassName: pure-block
volumeMode: Filesystem
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: volume-2-import-k8s-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 4Gi
  volumeName: volume-2-import-k8s-pv

2) Snapshot of a PVC and restore to a new PVC

The volume snapshot is created using the following definition example:

apiVersion: snapshot.storage.k8s.io/v1alpha1
kind: VolumeSnapshot
metadata:
   name: source-pvc-snap
spec:
   snapshotClassName: pure-snapshotclass
   source:
     name: source-pvc
     kind: PersistentVolumeClaim

Once deployed the volumesnapshot creates via the Pure Service Orchestrator CSI implementation a snapshot on the source volume within our Flasharray. I can now leverage this snapshot to create, for example, a pvc for a test dev deployment:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: restore-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
       storage: 1Gi
    storageClassName: pure-block
    dataSource:
      kind: VolumeSnapshot
      name: source-pvc-snap
      apiGroup: snapshot.storage.k8s.io

3) Resize of a PVC

The resize operation is initiated by editing / patching our persistent volume claim:

kubectl patch pvc {{ prefix }}-k8s-pvc-restore -p='{"spec": {"resources": {"requests": {"storage": "20Gi"}}}}'

The backend Flasharray volume as well as the persistent volume are resized immediately, but for the new space to be visible at the pvc and pod layers it requires the pod be restarted.

CSI features are maturing, and as shown Pure Storage provides up to date and simple integration to leverage these. This enables your end users to get access to the latest functionality without compromise or administration complexity.

Further documentation is available here.