Kubernetes kind : StorageClass - Dynamic Provisioning İçindir

Dynamic Volume Nedir?

Açıklaması şöyle

... in a managed environment it is highly recommended to have a facility where we can create volumes on-demand. Kubernetes provides Dynamic Volumes which eliminate the need to pre-provision volumes. To enable Dynamic Volumes we have to use a Kubernetes resource known as StorageClass . This object specifies which storage provisioner is to be used and the associated parameters.

Kullanım

StorageClass tipi PersistentVolume ile birlikte kullanılır. 

- provisioner mutlaka belirtilir.

- metadata.name ile belirtilen isim PersistentVolumeClaim tipinde storageClassName olarak kullanılır

Parametreler

Açıklaması şöyle

Each StorageClass contains the fields provisioner, parameters, and reclaimPolicy, which are used when a Persistent Volume belonging to the class needs to be dynamically provisioned.

Bir başka açıklama şöyle

provisioner: A StorageClass object contains a provisioner , that decides which volume plugin will be used to provision a PV. Kubernetes provides internal and external provisioners. Internal provisioners are also called “In-tree” volume plugins, which means their code is part of the core Kubernetes code and imported with the core Kubernetes binaries. We can also specify and run an external provisioner, which is also defined as Container Storage Interface(CSI).

parameters: Indicate properties of the underlying storage system.

reclaimPolicy: Can be either Delete​or Retain . Default is Delete

volumeBindingMode: Can be either Immediate or WaitForFirstConsumer

  Immediate — Immediately provisions PV after PVC is created.

  WaitForFirstConsumer— will delay the provisioning of a PV until a Pod using the PVC is created.

allowVolumeExpansion

Açıklaması şöyle

Resizing a Persistent Volume (PV) was very difficult prior to Kubernetes v1.11. It was an entirely manual process that involved a long list of steps, and required the creation of a new volume from a snapshot. You couldn’t just go and modify the PVC object to change the claim size.

Persistent volume expansion feature was promoted to beta in Kubernetes v1.11. This feature allows users to easily resize an existing volume by editing the PersistentVolumeClaim object. Users no longer have to manually interact with the storage backend or delete and recreate PV and PVC objects to increase the size of a volume. Shrinking persistent volumes is not supported though. You can find more information, including a list of volume types supported, here.

Although the feature is enabled by default, a cluster admin has to make the feature available to users by setting the allowVolumeExpansion field to true in their StorageClass object(s). Only PVCs created from a StorageClass with this setting will be allowed to trigger volume expansion.

Any PVC created from this StorageClass can be edited to request more space. Kubernetes will interpret a change to the storage field as a request for more space, and will trigger an automatic volume resizing.

Örnek

Şöyle yaparız

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
  name: gp2
parameters:
  fsType: ext4
  type: gp2
allowVolumeExpansion: true
provisioner: kubernetes.io/aws-ebs
reclaimPolicy: Delete
volumeBindingMode: Immediate

minikube Kullanımı

Örnek

minikube ile şöyle yaparız

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: fast
provisioner: k8s.io/minikube-hostpath
parameters:
  type: pd-ssd

Örnek

Şöyle yaparız

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: local-storage
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true
reclaimPolicy: Delete

Google Kullanımı

Örnek

Şöyle yaparız. Burada provisioner belirtiliyor ayrıca name olarak SSD olduğundan fast deniliyor

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast
provisioner: kubernetes.io/gce-pd
parameters:
  type: pd-ssd

Örnek

Açıklaması şöyle

For example, to use a SSD disk provided by Google Kubernetes Engine, create the following  StorageClass:

Örnek

Bir StorageClass yaratırız. Şöyle yaparız. Burada provisioner belirtiliyor.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: my-class
provisioner: kubernetes.io/gce-pd
parameters:
  type: pd-ssd

PersistentVolumeClaim   yaratırız. Şöyle yaparız

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: my-class
  resources:
    requests:
      storage: 30Gi

AWS EBS Kullanımı

Açıklaması şöyle

... for AWS EBS, there are various types of EBS volumes (gp2 , gp3 , io1 , io2 , etc). And also various configurations can be done, for example — enabling encryption, specifying minimum IOPS, and minimum throughput for an EBS volume.

Örnek

Şöyle yaparız

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: gp2
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp2
  fsType: ext4

Örnek

Şöyle yaparız

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: gp2-standard
provisioner: kubernetes.io/aws-ebs   # Internal-provisioner
parameters:
  type: gp2
reclaimPolicy: Retain
volumeBindingMode: Immediate

Örnek

Şöyle yaparız

---
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: gp2-standard
provisioner: ebs.csi.aws.com
parameters:
  type: gp2
volumeBindingMode: Immediate
reclaimPolicy: Retain
---
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: io2-encrypted
provisioner: ebs.csi.aws.com   
parameters:
  type: io2
  iopsPerGB: "3000"
  encrypted: "true"
volumeBindingMode: WaitForFirstConsumer
reclaimPolicy: Delete