使用StorageClass动态创建pv

rook-ceph安装部署到位后，就可以开始来尝试使用StorageClass来动态创建pv了。

有状态的中间件在kubernetes上落地基本上都会用到StorageClass来动态创建pv（对于云上应用没有那么多烦恼，云硬盘很好用，但是对于自己学习和练习来说还是Ceph更加靠谱），这里小试一试动态创建pv的威力，为后续用它来玩转redis、zookeeper、elasticsearch做准备。

1、创建 StorageClass和存储池

kubectl create -f rook/deploy/examples/csi/rbd/storageclass.yaml

查看创建的cephblockpool和StorageClass

kubectl get cephblockpool -n rook-ceph
kubectl get sc

结果如下：

rook/deploy/examples/csi/rbd/storageclass.yaml内容如下：

apiVersion: ceph.rook.io/v1
kind: CephBlockPool
metadata:
  name: replicapool
  namespace: rook-ceph # namespace:cluster
spec:
  failureDomain: host
  replicated:
    size: 2
    # Disallow setting pool with replica 1, this could lead to data loss without recovery.
    # Make sure you're *ABSOLUTELY CERTAIN* that is what you want
    requireSafeReplicaSize: true
    # gives a hint (%) to Ceph in terms of expected consumption of the total cluster capacity of a given pool
    # for more info: https://docs.ceph.com/docs/master/rados/operations/placement-groups/#specifying-expected-pool-size
    #targetSizeRatio: .5
---
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: rook-ceph-block
# Change "rook-ceph" provisioner prefix to match the operator namespace if needed
provisioner: rook-ceph.rbd.csi.ceph.com
parameters:
  # clusterID is the namespace where the rook cluster is running
  # If you change this namespace, also change the namespace below where the secret namespaces are defined
  clusterID: rook-ceph # namespace:cluster

  # If you want to use erasure coded pool with RBD, you need to create
  # two pools. one erasure coded and one replicated.
  # You need to specify the replicated pool here in the `pool` parameter, it is
  # used for the metadata of the images.
  # The erasure coded pool must be set as the `dataPool` parameter below.
  #dataPool: ec-data-pool
  pool: replicapool

  # (optional) mapOptions is a comma-separated list of map options.
  # For krbd options refer
  # https://docs.ceph.com/docs/master/man/8/rbd/#kernel-rbd-krbd-options
  # For nbd options refer
  # https://docs.ceph.com/docs/master/man/8/rbd-nbd/#options
  # mapOptions: lock_on_read,queue_depth=1024

  # (optional) unmapOptions is a comma-separated list of unmap options.
  # For krbd options refer
  # https://docs.ceph.com/docs/master/man/8/rbd/#kernel-rbd-krbd-options
  # For nbd options refer
  # https://docs.ceph.com/docs/master/man/8/rbd-nbd/#options
  # unmapOptions: force

   # (optional) Set it to true to encrypt each volume with encryption keys
   # from a key management system (KMS)
   # encrypted: "true"

   # (optional) Use external key management system (KMS) for encryption key by
   # specifying a unique ID matching a KMS ConfigMap. The ID is only used for
   # correlation to configmap entry.
   # encryptionKMSID: 

  # RBD image format. Defaults to "2".
  imageFormat: "2"

  # RBD image features
  # Available for imageFormat: "2". Older releases of CSI RBD
  # support only the `layering` feature. The Linux kernel (KRBD) supports the
  # full complement of features as of 5.4
  # `layering` alone corresponds to Ceph's bitfield value of "2" ;
  # `layering` + `fast-diff` + `object-map` + `deep-flatten` + `exclusive-lock` together
  # correspond to Ceph's OR'd bitfield value of "63". Here we use
  # a symbolic, comma-separated format:
  # For 5.4 or later kernels:
  #imageFeatures: layering,fast-diff,object-map,deep-flatten,exclusive-lock
  # For 5.3 or earlier kernels:
  imageFeatures: layering

  # The secrets contain Ceph admin credentials. These are generated automatically by the operator
  # in the same namespace as the cluster.
  csi.storage.k8s.io/provisioner-secret-name: rook-csi-rbd-provisioner
  csi.storage.k8s.io/provisioner-secret-namespace: rook-ceph # namespace:cluster
  csi.storage.k8s.io/controller-expand-secret-name: rook-csi-rbd-provisioner
  csi.storage.k8s.io/controller-expand-secret-namespace: rook-ceph # namespace:cluster
  csi.storage.k8s.io/node-stage-secret-name: rook-csi-rbd-node
  csi.storage.k8s.io/node-stage-secret-namespace: rook-ceph # namespace:cluster
  # Specify the filesystem type of the volume. If not specified, csi-provisioner
  # will set default as `ext4`. Note that `xfs` is not recommended due to potential deadlock
  # in hyperconverged settings where the volume is mounted on the same node as the osds.
  csi.storage.k8s.io/fstype: ext4
# uncomment the following to use rbd-nbd as mounter on supported nodes
# **IMPORTANT**: CephCSI v3.4.0 onwards a volume healer functionality is added to reattach
# the PVC to application pod if nodeplugin pod restart.
# Its still in Alpha support. Therefore, this option is not recommended for production use.
#mounter: rbd-nbd
allowVolumeExpansion: true
reclaimPolicy: Delete

2、创nginx的StatefulSet，通过storageclass来动态创建pv绑定到 /usr/share/nginx/html    有状态的Pod,每个Pod都要有自己的pv。    对于redis、zookeeper、elasticsearch来说都会使用到storageClass来动态创建pv。

 kubectl apply -f test_volumnClainTemplates.yaml 

  查看命令如下：

kubectl get po -l app=nginx
kubectl get pvc

   结果如下：

   test_volumnClainTemplates.yaml的内容如下：

apiVersion: v1
kind: Service
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  selector:
    matchLabels:
      app: nginx
  serviceName: "nginx"
  replicas: 2  
  template:
    metadata: 
      labels:
        app: nginx
    spec:
      terminationGracePeriodSeconds: 10 
      containers:
      - name: nginx 
        image: nginx 
        ports:
        - containerPort: 80 
          name: web
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: www 
    spec:
      accessModes: [ "ReadWriteOnce" ] 
      storageClassName: "rook-ceph-block"
      resources:
        requests:
          storage: 200M