How to rename persistence volume claim? - kubernetes

Question

Is is possible to rename a PVC? I can't seem to find an evidence it is possible.
I'm trying mitigate an "No space left of device" issue I just stumbled upon. Essentially my plan requires me to resize the volume, on which my service persists its data.
Unfortunately I'm still on Kubernetes 1.8.6 on GKE. It does not have the PersistentVolumeClaimResize admission plugin enabled:
1.9.1: config-default.sh#L254#1.9.1
1.8.6: config-default.sh#L254#1.8.6
Therefor I have to try and save the data manually. I made the following plan:
create a new, bigger volume PVC,
create a temp container with attached "victim" pvc and a new bigger pvc,
copy the data,
drop "victim" PVC,
rename new bigger pvc to take place of "victim".
The PVC in question is attached to StatefulSet, so the old and new names must match (as StatefulSet expects follows the volume naming convention).
But I don't understand how to rename persistent volume claims.

Answer 1

The answer of your question is NO. There is no way to change any meta name in Kubernetes.
But, there is a way to fulfill your requirement.
You want to claim your new bigger PersistentVolume by old PersistentVolumeClaim.
Lets say, old PVC named victim and new PVC named bigger. You want to claim PV created for bigger by victim PVC. Because your application is already using victim PVC.
Follow these steps to do the hack.
Step 1: Delete your old PVC victim.
Step 2: Make PV of bigger Available.
$ kubectl get pvc bigger
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
bigger Bound pvc-8badc3c2-08c5-11e8-b07a-080027b3e1a6 10Gi RWO standard 30s
Edit PV pvc-8badc3c2-08c5-11e8-b07a-080027b3e1a6 to set persistentVolumeReclaimPolicy to Retain. So that deleting PVC will not delete PV.
Now, delete PVC bigger.
$ kubectl delete pvc bigger
$ kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-8badc3c2-08c5-11e8-b07a-080027b3e1a6 10Gi RWO Retain Released default/bigger standard 3m
See the status, PV is Released.
Now, make this PV available to be claimed by another PVC, our victim.
Edit PV again to remove claimRef
$ kubectl edit pv pvc-8badc3c2-08c5-11e8-b07a-080027b3e1a6
$ kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-8badc3c2-08c5-11e8-b07a-080027b3e1a6 10Gi RWO Retain Available standard 6m
Now the status of PV is Available.
Step 3: Claim bigger PV by victim PVC
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: victim
spec:
accessModes:
- ReadWriteOnce
volumeName: pvc-8badc3c2-08c5-11e8-b07a-080027b3e1a6
resources:
requests:
storage: 10Gi
Use volumeName pvc-8badc3c2-08c5-11e8-b07a-080027b3e1a6
kubectl get pvc,pv
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
pvc/victim Bound pvc-8badc3c2-08c5-11e8-b07a-080027b3e1a6 10Gi RWO standard 9s
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pv/pvc-8badc3c2-08c5-11e8-b07a-080027b3e1a6 10Gi RWO Retain Bound default/victim standard 9m
Finally: Set persistentVolumeReclaimPolicy to Delete
This is how, your PVC victim has had bigger PV.

Answer 2

With Kubernetes 1.11+ you can perform on-demand resizing by simply modifying the PVC's storage request (https://kubernetes.io/blog/2018/07/12/resizing-persistent-volumes-using-kubernetes/).
GKE supports this (I've used it several times my self) and it's pretty straightforward and without the drama.

Answer 3

I cannot validate this however I am fairly certain that for GKE you can go to disks in the Google Cloud Console and find the one that the PV uses and resize it there. Once you've done that you should be able to log into the node which its attached and run resize2fs on the device. This is dirty, but fairly certain this has worked for me once in the past.
You don't have to unmount or copy to do this, which can save you if the disk is live or large.