Snapshotting on google cloud/Kubernetes when using storageClass persistent volumes - kubernetes

Question

StorageClasses are the new method of specifying dynamic persistent volume claim (PVC) dependencies within Kubernetes. This avoids the need to explicitly provision one directly with the cloud provider (in my case Google Container Engine (GKE)).
Definition for the StorageClasses (GKE already has a default for standard class)
---
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: fast
provisioner: kubernetes.io/gce-pd
parameters:
type: pd-ssd
zone: europe-west1-b
Definition for the actual PVC
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: nfs-server-pvc
namespace: staging
spec:
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 100Gi
storageClassName: "standard"
Here is the result of kubernetes get storageclass:
NAME TYPE
fast kubernetes.io/gce-pd
standard (default) kubernetes.io/gce-pd
Here is the result of kubernetes get pvc:
NAME STATUS VOLUME CAPACITY ACCESSMODES STORAGECLASS AGE
nfs-pvc Bound nfs 1Mi RWX 119d
nfs-server-pvc Bound pvc-905a810b-3f13-11e7-82f9-42010a840072 100Gi RWO standard 81d
I would like to continue taking snapshots of the volumes but the dynamic nature of the volume names created (in this case pvc-905a810b-3f13-11e7-82f9-42010a840072), mean i cannot continue with the following command that i had been using via cron (note the "nfs" name is now incorrect):
gcloud compute --project "XXX-XXX" disks snapshot "nfs" --zone "europe-west1-b" --snapshot-names "nfs-${DATE}"
I guess this boils down to Kubernetes allowing explicit naming through StorageClass-based PVC. The docs don't seem to allow this. Any ideas?

Answer 1

One approach is to manually create the PV and give it a stable name that you can use in your scripts. You can use gcloud commands to create the underlying PD disks. When you create the PV, give it a label:
apiVersion: "v1"
kind: "PersistentVolume"
metadata:
name: my-pv-0
labels:
pdName: my-pv-0
spec:
capacity:
storage: "10Gi"
accessModes:
- "ReadWriteOnce"
storageClassName: fast
gcePersistentDisk:
fsType: "ext4"
pdName: "my-pd-0"
Then attach it to the PVC using a selector:
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: my-pvc-0
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
storageClassName: fast
selector:
matchLabels:
pdName: my-pv-0