k8s集成cephfs(StorageClass方式)

k8s 中 pv 有以下三种访问模式(Access Mode)：

• ReadWriteOnce：只可被一个Node挂载，这个Node对PV拥有读写权限
• ReadOnlyMany: 可以被多个Node挂载，这些Node对PV只有只读权限
• ReadWriteMany: 可以被多个Node挂载，这些Node对PV拥有读写权限

ceph rbd 模式是不支持 ReadWriteMany，而 cephfs 是支持的，详见官方文档 Persistent Volumes | Kubernetes

还有一点，当创建 ceph rbd 的 storageclass 时，k8s 官方集成了 provisioner 的，只需指定 provisioner: kubernetes.io/rbd 即可；

而 cephfs 的 provisioner 当前是并未集成的，所以需要额外自行安装 cephfs-provisioner，具体方法如下：

1. ceph 集群创建 cephfs

   ceph-deploy mds create ceph01
   ceph-deploy mds create ceph02
   ceph-deploy mds create ceph03
   ceph osd pool create cephfs_data 64
   ceph osd pool create cephfs_metadata 64
   ceph fs new cephfs cephfs_metadata cephfs_data
   ceph fs ls
   

2. 获取 key

   $ ceph auth get-key client.admin | base64
   QVFEMjVxVmhiVUNJRHhBQUxwdmVHbUdNTWtXZjB6VXovbWlBY3c9PQ==
   

3. k8s 集群节点安装 ceph-common，版本需和 ceph 集群一致

   rpm -ivh http://download.ceph.com/rpm-luminous/el7/noarch/ceph-release-1-1.el7.noarch.rpm
   sed -i 's#download.ceph.com#mirrors.aliyun.com/ceph#g' /etc/yum.repos.d/ceph.repo
   yum install epel-release -y
   yum install -y ceph-common
   

4. 安装 cephfs-provisioner

   git clone https://github.com/kubernetes-retired/external-storage.git
   cd external-storage/ceph/cephfs/deploy
   kubectl create namespace cephfs
   kubectl -n cephfs apply -f ./rbac/
   

5. 编辑 storageclass yaml 文件

   $ vi ceph-sc.yaml
   apiVersion: v1
   kind: Secret
   metadata:
     name: cephfs-storageclass-secret
     namespace: cephfs
   data:
     key: QVFEMjVxVmhiVUNJRHhBQUxwdmVHbUdNTWtXZjB6VXovbWlBY3c9PQ==
   ---
   apiVersion: storage.k8s.io/v1
   kind: StorageClass
   metadata:
     name: cephfs-leffss
     annotations:
       storageclass.kubernetes.io/is-default-class: "false"
   provisioner: ceph.com/cephfs
   parameters:
     monitors: 10.10.10.51:6789,10.10.10.53:6789,10.10.10.53:6789
     # 不能使用主机名方式，因为前面安装的 cephfs-provisioner 的 pod 是无法访问的
     #monitors: ceph01:6789,ceph02:6789,ceph03:6789
     adminId: admin
     adminSecretName: cephfs-storageclass-secret
     adminSecretNamespace: cephfs
     claimRoot: /k8s-volumes
   

   测试 yaml：

   kind: PersistentVolumeClaim
   apiVersion: v1
   metadata:
     name: ceph-pvc-test1
     namespace: default
     annotations:
       volume.beta.kubernetes.io/storage-class: cephfs-leffss
   spec:
     accessModes:
       - ReadWriteMany
     resources:
       requests:
         storage: 1Gi
   ---
   kind: Pod
   apiVersion: v1
   metadata:
     name: test-pod-1
   spec:
     containers:
     - name: test-pod-1
       image: hub.leffss.com/library/busybox:v1.29.2
       command:
         - "/bin/sh"
       args:
         - "-c"
         - "touch /mnt/SUCCESS-ceph-pvc-test1 && exit 0 || exit 1"
       volumeMounts:
         - name: pvc
           mountPath: "/mnt"
     restartPolicy: "Never"
     volumes:
       - name: pvc
         persistentVolumeClaim:
           claimName: ceph-pvc-test1
           
   
   kind: PersistentVolumeClaim
   apiVersion: v1
   metadata:
     name: ceph-pvc-test2
     namespace: default
   spec:
     storageClassName: cephfs-leffss
     accessModes:
       - ReadWriteMany
     resources:
       requests:
         storage: 1Gi
   ---
   kind: Pod
   apiVersion: v1
   metadata:
     name: test-pod-2
   spec:
     containers:
     - name: test-pod-2
       image: hub.leffss.com/library/busybox:v1.29.2
       command:
         - "/bin/sh"
       args:
         - "-c"
         - "touch /mnt/SUCCESS-ceph-pvc-test2 && exit 0 || exit 1"
       volumeMounts:
         - name: pvc
           mountPath: "/mnt"
     restartPolicy: "Never"
     volumes:
       - name: pvc
         persistentVolumeClaim:
           claimName: ceph-pvc-test2
   

6. 验证

   $ ceph auth get-key client.admin
   AQD25qVhbUCIDxAALpveGmGMMkWf0zUz/miAcw==
   
   $ mkdir /mycephfs
   $ mount -t ceph ceph01:6789,ceph02:6789,ceph03:6789:/ /mycephfs -o name=admin,secret=AQD25qVhbUCIDxAALpveGmGMMkWf0zUz/miAcw==
   
   $ tree /mycephfs
   /mycephfs
   └── k8s-volumes
       ├── kubernetes
       │   ├── kubernetes-dynamic-pvc-59ea31d4-52a4-11ec-962a-567006a2be7a
       │   │   └── SUCCESS-ceph-pvc-test1
       │   └── kubernetes-dynamic-pvc-6553ea70-52a4-11ec-962a-567006a2be7a
       │       └── SUCCESS-ceph-pvc-test2
       ├── _kubernetes:kubernetes-dynamic-pvc-59ea31d4-52a4-11ec-962a-567006a2be7a.meta
       └── _kubernetes:kubernetes-dynamic-pvc-6553ea70-52a4-11ec-962a-567006a2be7a.meta
   
   4 directories, 4 filess
   

最后说一点：cephfs 不太稳定，建议生产不要使用，我在测试环境都会遇到使用 cephfs 后导致 ceph 集群异常的情况