pvc-autoresizer

pvc-autoresizer

pvc-autoresizer resizes PersistentVolumeClaims (PVCs) when the free amount of storage is below the threshold. It queries the volume usage metrics from Prometheus that collects metrics from kubelet.

Status: beta

Target CSI Drivers

pvc-autoresizer supports CSI Drivers that meet the following requirements:

• implement Volume Expansion.
• implement NodeGetVolumeStats

Prepare

pvc-autoresizer behaves based on the metrics that prometheus collects from kubelet.

Please refer to the following pages to set up Prometheus:

• Installation | Prometheus

In addition, configure scraping as follows:

• Monitoring with Prometheus | TopoLVM

Installation

Specify the Prometheus URL to pvc-autoresizer argument as --prometheus-url.

pvc-autoresizer can be deployed to a Kubernetes cluster via kustomize and kubectl:

kustomize build ./config/default | kubectl apply -f -

How to use

To allow auto volume expansion, the StorageClass of PVC need to allow volume expansion and have resize.topolvm.io/enabled: "true" annotation. The annotation may be omitted if you give --no-annotation-check command-line flag to pvc-autoresizer executable.

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: topolvm-provisioner
  annotations:
    resize.topolvm.io/enabled: "true"
provisioner: topolvm.cybozu.com
allowVolumeExpansion: true

To allow auto volume expansion, the PVC to be resized need to specify the upper limit of volume size with the annotation resize.topolvm.io/storage_limit or the PVC spec .spec.resources.limits.storage (if both are present, the annotation takes precedence). The PVC must have volumeMode: Filesystem too.

The PVC can optionally have resize.topolvm.io/threshold and resize.topolvm.io/increase annotations. (If they are not given, the default value is 10%.)

When the amount of free space of the volume is below resize.topolvm.io/threshold, .spec.resources.requests.storage is increased by resize.topolvm.io/increase.

If resize.topolvm.io/increase is given as a percentage, the value is calculated as the current spec.resources.requests.storage value multiplied by the annotation value.

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: topolvm-pvc
  namespace: default
  annotations:
    resize.topolvm.io/threshold: 20%
    resize.topolvm.io/increase: 20Gi
spec:
  accessModes:
  - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 30Gi
    limits:
      storage: 100Gi
  storageClassName: topolvm-provisioner

Container images

Container images are available on Quay.io