一、使用helm安装redis

执行以下命令添加redis的repo

helm repo add bitnami https://charts.bitnami.com/bitnami

创建的master和replica pod的默认size是8Gi，如果k8s的node没有足够的空间，会抛出如下错误：default-scheduler  0/3 nodes are available: pod has unbound immediate PersistentVolumeClaims. preemption: 0/3 nodes are available: 3 No preemption victims found for incoming pod为此，我们可以扩大node的size，或在安装时重新设置pod的size，设置方法如下：

helm install --set replica.persistence.size=2Gi --set master.persistence.size=2Gi my-redis bitnami/redis

 其他参数请参见redis 17.11.6 · bitnami/bitnami

二、创建并部署storageclass

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

三、创建并部署PV (persistent volumes)

apiVersion: v1
kind: PersistentVolume
metadata:
  name: $pv_name
spec:
  storageClassName: manual
  capacity:
    storage: 2Gi
  accessModes:
  - ReadWriteOnce
  hostPath:
    path: $data_path

pv的storageClassName指向先前创建的storageclass (manual)。此外，还需要指定data的存放路径 hostPath，这要求在k8s的各node上创建该路径，并修改路径权限；

chmod 777 $data_path

否则pod会抛出如下错误: Can't open or create append-only dir appendonlydir: Permission denied

四、修改pvc

修改redis下master & replica pod使用的pvc，使其指向步骤3中创建的pv

metadata:
  annotations:
    pv.kubernetes.io/bind-completed: "yes"
    pv.kubernetes.io/bound-by-controller: "yes"
  creationTimestamp: "2023-06-29T11:18:24Z"
  finalizers:
  - kubernetes.io/pvc-protection
  labels:
    app.kubernetes.io/component: master
    app.kubernetes.io/instance: my-redis
    app.kubernetes.io/name: redis
  name: redis-data-my-redis-master-0
  namespace: default
  resourceVersion: "2608115"
  uid: 4f1b0e39-8078-4fdc-8aff-388437ab9922
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi
  storageClassName: $storage_name #指定storage name
  volumeMode: Filesystem
  volumeName: $pv_name #指定pv
status:
  accessModes:
  - ReadWriteOnce
  capacity:
    storage: 2Gi
  phase: Bound
~              

五、重要参考文献

1. storage、pv、pvc的关联关系及配置方法
kubernetes - Error "no persistent volumes available for this claim and no storage class is set" - Stack Overflow

 2. 详细的安装过程

iDeploying Redis Cluster on Kubernetes | AirplaneiyIn this guide, learn how to run Redis on Kubernetes and explore tips for improving performance, security, and more.https://www.airplane.dev/blog/deploy-redis-cluster-on-kubernetes

 六、相关知识点

 通过层层的关联关系实现了host上的path与container上path的绑定（mount），进而实现在container销毁的情况下，其在mountpath下内容会存储在hostpath中。

volume

On-disk files in a container are ephemeral, which presents some problems for non-trivial applications when running in containers. One problem occurs when a container crashes or is stopped. Container state is not saved so all of the files that were created or modified during the lifetime of the container are lost. During a crash, kubelet restarts the container with a clean state. Another problem occurs when multiple containers are running in a Pod and need to share files. It can be challenging to setup and access a shared filesystem across all of the containers. The Kubernetes volume abstraction solves both of these problems. Familiarity with Pods is suggested.

 a volume is a directory, possibly with some data in it, which is accessible to the containers in a pod. How that directory comes to be, the medium that backs it, and the contents of it are determined by the particular volume type used.

 Ephemeral volume types have a lifetime of a pod, but persistent volumes exist beyond the lifetime of a pod. When a pod ceases to exist, Kubernetes destroys ephemeral volumes; however, Kubernetes does not destroy persistent volumes. For any kind of volume in a given pod, data is preserved across container restarts.