1、創建ceph-secret這個k8s secret對象，這個secret對象用于k8s volume插件訪問ceph集群，獲取client.admin的keyring值，并用base64編碼，在master1-admin（ceph管理節點）操作

[root@master1-admin ~]# ceph auth get-key client.admin | base64 QVFDOWF4eGhPM0UzTlJBQUJZZnVCMlZISVJGREFCZHN0UGhMc3c9PQ==

?2.創建ceph的secret，在k8s的控制節點操作：

[root@master ceph]# cat ceph-secret.yaml apiVersion: v1 kind: Secret metadata:name: ceph-secret data:key: QVFDOWF4eGhPM0UzTlJBQUJZZnVCMlZISVJGREFCZHN0UGhMc3c9PQ== [root@master ceph]# kubectl apply -f ceph-secret.yaml secret/ceph-secret created

3.回到ceph 管理節點創建pool池，然后再創建一個塊設備

[root@master1-admin ~]# ceph osd pool create k8stest 56 pool 'k8stest' created You have new mail in /var/spool/mail/root [root@master1-admin ~]# rbd create rbda -s 1024 -p k8stest [root@master1-admin ~]# rbd feature disable k8stest/rbda object-map fast-diff deep-flatten [root@master1-admin ~]# ceph osd pool ls rbd cephfs_data cephfs_metadata k8srbd1 k8stest

?4、創建pv

[root@master ceph]# cat pv.yaml apiVersion: v1 kind: PersistentVolume metadata: name: ceph-pv spec: capacity: storage: 1Gi accessModes: - ReadWriteOnce rbd: monitors: - '192.168.0.5:6789'- '192.168.0.6:6789'- '192.168.0.7:6789' pool: k8stest image: rbda user: admin secretRef: name: ceph-secret fsType: xfs readOnly: false persistentVolumeReclaimPolicy: Recycle[root@master ceph]# vim pv.yaml [root@master ceph]# kubectl apply -f pv.yaml persistentvolume/ceph-pv created[root@master ceph]# kubectl get pv NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM ceph-pv 1Gi RWO Recycle Available [root@master ceph]# cat pvc.yaml kind: PersistentVolumeClaim apiVersion: v1 metadata: name: ceph-pvc spec: accessModes: - ReadWriteOnce resources: requests: storage: 1Gi[root@master ceph]# kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE ceph-pvc Bound ceph-pv 1Gi RWO 4s[root@master ceph]# kubectl get pv NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE ceph-pv 1Gi RWO Recycle Bound default/ceph-pvc 5h23m [root@master ceph]# cat pod-2.yaml apiVersion: apps/v1 kind: Deployment metadata:name: nginx-deployment spec:selector:matchLabels:app: nginxreplicas: 2 # tells deployment to run 2 pods matching the templatetemplate: # create pods using pod definition in this templatemetadata:labels:app: nginxspec:containers:- name: nginximage: nginximagePullPolicy: IfNotPresentports:- containerPort: 80volumeMounts:- mountPath: "/ceph-data"name: ceph-datavolumes:- name: ceph-datapersistentVolumeClaim:claimName: ceph-pvc[root@master ceph]# kubectl apply -f pod-2.yaml deployment.apps/nginx-deployment created[root@master ceph]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nginx-deployment-d9f89fd7c-v8rxb 1/1 Running 0 12s 10.233.90.179 node1 <none> <none> nginx-deployment-d9f89fd7c-zfwzj 1/1 Running 0 12s 10.233.90.178 node1 <none> <none>

通過上面可以發現pod是可以以ReadWriteOnce共享掛載相同的pvc的?

注意：ceph?rbd塊存儲的特點

• ?ceph rbd塊存儲能在同一個node上跨pod以ReadWriteOnce共享掛載
• ceph rbd塊存儲能在同一個node上同一個pod多個容器中以ReadWriteOnce共享掛載
• ceph rbd塊存儲不能跨node以ReadWriteOnce共享掛載
• 如果一個使用ceph rdb的pod所在的node掛掉，這個pod雖然會被調度到其它node，但是由于rbd不能跨node多次掛載和掛掉的pod不能自動解綁pv的問題，這個新pod不會正常運行

#將之前所在的節點關閉，可以看到不能使用pvc[root@master ceph]# kubectl get pod NAME READY STATUS RESTARTS AGE nfs-client-provisioner-867b44bd69-nhh4m 1/1 Running 0 9m30s nfs-client-provisioner-867b44bd69-xscs6 1/1 Terminating 2 18d nginx-deployment-d9f89fd7c-4rzjh 1/1 Terminating 0 15m nginx-deployment-d9f89fd7c-79ncq 1/1 Terminating 0 15m nginx-deployment-d9f89fd7c-p54p9 0/1 ContainerCreating 0 9m30s nginx-deployment-d9f89fd7c-prgt5 0/1 ContainerCreating 0 9m30sEvents:Type Reason Age From Message---- ------ ---- ---- -------Normal Scheduled 11m default-scheduler Successfully assigned default/nginx-deployment-d9f89fd7c-p54p9 to node2Warning FailedAttachVolume 11m attachdetach-controller Multi-Attach error for volume "ceph-pv" Volume is already used by pod(s) nginx-deployment-d9f89fd7c-79ncq, nginx-deployment-d9f89fd7c-4rzjhWarning FailedMount 25s (x5 over 9m26s) kubelet, node2 Unable to attach or mount volumes: unmounted volumes=[ceph-data], unattached volumes=[ceph-data default-token-cwbdx]: timed out waiting for the condition

?

Deployment更新特性：

deployment觸發更新的時候，它確保至少所需 Pods 75% 處于運行狀態（最大不可用比例為 25%）。故像一個pod的情況，肯定是新創建一個新的pod，新pod運行正常之后，再關閉老的pod。

默認情況下，它可確保啟動的 Pod 個數比期望個數最多多出 25%

問題：

結合ceph rbd共享掛載的特性和deployment更新的特性，我們發現原因如下：

由于deployment觸發更新，為了保證服務的可用性，deployment要先創建一個pod并運行正常之后，再去刪除老pod。而如果新創建的pod和老pod不在一個node，就會導致此故障。

解決辦法：

1，使用能支持跨node和pod之間掛載的共享存儲，例如cephfs，GlusterFS等

2，給node添加label，只允許deployment所管理的pod調度到一個固定的node上。（不建議，這個node掛掉的話，服務就故障了）

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