[k8s] Storage Class
============
###### tags: `kubernetes`

:::warning
+ A storageclass is a Kubernetes object that ***<span style="color: red">stores information about creating a persistent volume</span>*** for your pod.
+ With a storageclass, you **do not need to create a persistent volume** separately before claiming it.
:::

## how to work

## types of provisioner

### example




## dynamic provisioning (pv)
> [color=violet]PersistentVolumes that are dynamically created by a StorageClass


# sc-definition.yaml
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: google-storage
provisioner: kubernetes.io/gce-pd
parameters:
  type: pd-standard [ pd-standard | pd-ssd ]
  replication-type: none [ none | regional-pd]

# pvc-definition.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: myclaim
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: google-storage
  resources:
    requests:
      storage: 500Mi

# pod-definition.yaml
apiVersion: v1
kind: Pod
metadata:
  name: random-number-generator
spec:
  containers:
  - image: alpine
    name: alpine
    command: ["/bin/sh", "-c"]
    args: ["shuf -i 0-100 -n 1 >> /opt/number.out;"]
    volumeMounts:
    - mountPath: /opt
      name: data-volume 
  volumes:
  - name: data-volume
    persistentVolumeClaim:
      claimName: myclaim

### parameters
+ <kbd>volumeBindingMode</kbd>
+ `WaitForFirstConsumer` - This will ***delay the binding and provisioning*** of a PersistentVolume **until** a Pod using the PersistentVolumeClaim is created.
+ `Immediate`
## static provisioning
> [color=skyblue] storageClass描述了dynamic provision 的規範，但在static provision 中也可以使用。

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

即使你要手动配置 persistent volume，你仍然可以定義一個 storageClass 来为它们提供参数和配置。这样做有以下好處：

1. **集中管理配置**：静态存储类允许你将所有静态持久卷的配置集中在一个地方。这样，你可以更容易地修改、管理和维护这些卷的配置。
2. **规范化参数**：通过存储类，你可以定义参数并确保静态卷的一致性。这在多个持久卷之间尤其有用。
3. **可重用性**：存储类可以在多个静态卷之间共享，使得你可以轻松地创建具有相似配置的静态卷。

因此，虽然存储类主要用于动态供给，但也可以为静态供给提供一种标准化和集中化的配置方式。通过使用存储类，你可以更方便地管理和配置你的静态持久卷。