Kubernetes使用Ceph动态卷部署应用

Kubernetes使用Ceph动态卷部署应用

1. 环境准备

可用的kubernetes，版本1.11.1
可用的Ceph集群，版本luminous
Ceph monitor节点：lab1、lab2、lab3

# k8s
192.168.105.92 lab1 # master1
192.168.105.93 lab2 # master2
192.168.105.94 lab3 # master3
192.168.105.95 lab4 # node4
192.168.105.96 lab5 # node5
192.168.105.97 lab6 # node6
192.168.105.98 lab7 # node7

GO语言环境和kubernetes-incubator/external-storage源码

yum install -y golang
mkdir -p $HOME/go/src/github.com/kubernetes-incubator
cat >>$HOME/.bash_profile<export GOROOT=/usr/lib/golang
export GOPATH=\$HOME/go
EOF
cd $HOME/go/src/github.com/kubernetes-incubator
git clone https://github.com/kubernetes-incubator/external-storage.git

私有docker仓库Harbor帐户生成secret添加至k8s

kubectl create secret docker-registry 97registrykey --docker-server=192.168.105.97 --docker-username=k8s --docker-password='PWD'
docker login 192.168.105.97  # 提前登录，避免后续docker push失败

2. CephFS方式创建pvc

2.1 编译并上传docker image

cd $HOME/go/src/github.com/kubernetes-incubator/external-storage/ceph/cephfs

准备docker image的yum源文件：

vim epel-7.repo

[epel]
name=Extra Packages for Enterprise Linux 7 - $basearch
baseurl=http://mirrors.aliyun.com/epel/7/$basearch
failovermethod=priority
enabled=1
gpgcheck=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

[epel-debuginfo]
name=Extra Packages for Enterprise Linux 7 - $basearch - Debug
baseurl=http://mirrors.aliyun.com/epel/7/$basearch/debug
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
gpgcheck=0

[epel-source]
name=Extra Packages for Enterprise Linux 7 - $basearch - Source
baseurl=http://mirrors.aliyun.com/epel/7/SRPMS
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
gpgcheck=0

vim ceph.repo

[Ceph]
name=Ceph packages for $basearch
baseurl=https://mirrors.aliyun.com/ceph/rpm-luminous/el7/$basearch
enabled=1
gpgcheck=1
type=rpm-md
gpgkey=https://mirrors.aliyun.com/ceph/keys/release.asc

[Ceph-noarch]
name=Ceph noarch packages
baseurl=https://mirrors.aliyun.com/ceph/rpm-luminous/el7/noarch
enabled=1
gpgcheck=1
type=rpm-md
gpgkey=https://mirrors.aliyun.com/ceph/keys/release.asc

[ceph-source]
name=Ceph source packages
baseurl=https://mirrors.aliyun.com/ceph/rpm-luminous/el7/SRPMS
enabled=1
gpgcheck=1
type=rpm-md
gpgkey=https://mirrors.aliyun.com/ceph/keys/release.asc

修改Makefile中的docker仓库地址

vim Makefile修改内容：

ifeq ($(REGISTRY),)
        REGISTRY = 192.168.105.97/pub/
endif

vim Dockerfile修改内容：

FROM centos:7

ENV CEPH_VERSION "luminous"  # 修改成ceph版本
COPY epel-7.repo /etc/yum.repos.d/  # 前面准备的yum源文件
COPY ceph.repo /etc/yum.repos.d/
RUN rpm --import 'https://mirrors.aliyun.com/ceph/keys/release.asc' && \
  yum install -y ceph-common python-cephfs && \
  yum clean all

编译并上传image至docker仓库

make  # 编译生成provisioner
make push  # 生成docker image并上传至docker仓库

2.2 创建Ceph admin secret

# 方法一
ceph auth get-key client.admin > /tmp/secret
kubectl create namespace ceph
kubectl create secret generic ceph-admin-secret --from-file=/tmp/secret --namespace=kube-system

2.2 启动CephFS provisioner

修改image地址：

cd $HOME/go/src/github.com/kubernetes-incubator/external-storage/ceph/cephfs/deploy
vim rbac/deployment.yaml 

    spec:
      imagePullSecrets:  # 添加k8s使用docker pull时的secret
        - name: 97registrykey
      containers:
      - name: cephfs-provisioner
        image: "192.168.105.97/pub/cephfs-provisioner:latest"  # 替换成私有image

部署启动

NAMESPACE=ceph # change this if you want to deploy it in another namespace
sed -r -i "s/namespace: [^ ]+/namespace: $NAMESPACE/g" ./rbac/*.yaml
kubectl -n $NAMESPACE apply -f ./rbac

2.3 创建动态卷和应用

cd /tmp

修改Ceph集群的monitor节点的IP，我的环境修改如下：

vim cephfs-class.yaml

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: cephfs
provisioner: ceph.com/cephfs
parameters:
    monitors: 192.168.105.92:6789,192.168.105.93:6789,192.168.105.94:6789
    adminId: admin
    adminSecretName: ceph-admin-secret
    adminSecretNamespace: "kube-system"
    claimRoot: /volumes/kubernetes

vim cephfs-claim.yaml

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: cephfs-pv-claim2
  annotations:
    volume.beta.kubernetes.io/storage-class: "cephfs"
spec:
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 2Gi

vim cephfs-nginx-dy.yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx-cephfs-dy
spec:
  replicas: 1
  template:
    metadata:
      labels:
        name: nginx
    spec:
      containers:
        - name: nginx
          image: nginx
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 80
          volumeMounts:
            - name: ceph-cephfs-volume
              mountPath: "/usr/share/nginx/html"
      volumes:
      - name: ceph-cephfs-volume
        persistentVolumeClaim:
          claimName: cephfs-pv-claim2

kubectl create -f cephfs-class.yaml
kubectl create -f cephfs-claim.yaml
# kubectl logs -f cephfs-provisioner-968b56c67-vgln7 -n ceph
# 等待上面日志出现成功结果再执行
# 成功日志类似：ProvisioningSucceeded' Successfully provisioned volume
kubectl create -f cephfs-nginx-dy.yaml                                          

验证结果：

[root@lab1 example]# kubectl get pvc
NAME               STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
cephfs-pv-claim1   Bound     cephfs-pv1                                 1Gi        RWX                           19h
cephfs-pv-claim2   Bound     pvc-b535d9b6-a5b7-11e8-b4fa-000c2931d938   2Gi        RWX            cephfs         33m
rbd-pv-claim1      Bound     rbd-pv1                                    2Gi        RWO                           17h
[root@lab1 example]# kubectl get pod
NAME                                READY     STATUS    RESTARTS   AGE
curl-87b54756-zkp68                 1/1       Running   0          17h
nginx-cephfs-7777495b9b-wshjh       1/1       Running   0          17h
nginx-cephfs-dy-86bdbfd977-zwqrb    1/1       Running   0          53s
nginx-deployment-7f46fc97b9-qmttl   1/1       Running   2          1d
nginx-deployment-7f46fc97b9-wg76n   1/1       Running   0          17h
nginx-rbd-6b555f58c9-nhnmh          1/1       Running   0          17h
rbd-provisioner-6cd6577964-cbn6v    1/1       Running   0          20h
[root@lab1 example]# kubectl exec -it nginx-cephfs-dy-86bdbfd977-zwqrb -- df -h|grep nginx
192.168.105.92:6789,192.168.105.93:6789,192.168.105.94:6789:/volumes/kubernetes/kubernetes/kubernetes-dynamic-pvc-24ba8f39-a5bc-11e8-a66c-0a580af4058e  1.6T   19G  1.6T   2% /usr/share/nginx/html

3. RBD方式创建pvc

3.1 编译并上传docker image

同上文，略

3.2 创建Ceph admin secret

# 方法二
ceph auth get client.admin 2>&1 |grep "key = " |awk '{print  $3'} |xargs echo -n > /tmp/secret
kubectl create secret generic ceph-admin-secret --from-file=/tmp/secret --namespace=kube-system

3.3 创建Ceph pool 和user secret

ceph osd pool create kube 128 128
ceph auth add client.kube mon 'allow r' osd 'allow rwx pool=kube'
ceph auth get-key client.kube > /tmp/kube.secret
kubectl create secret generic ceph-secret --from-file=/tmp/kube.secret --namespace=kube-system

2.2 启动Ceph rbd provisioner

修改image地址：

cd $HOME/go/src/github.com/kubernetes-incubator/external-storage/ceph/rbd/deploy
vim rbac/deployment.yaml 

    spec:
      imagePullSecrets:  # 添加k8s使用docker pull时的secret
        - name: 97registrykey
      containers:
      - name: cephfs-provisioner
        image: "192.168.105.97/pub/rbd-provisioner:latest"  # 替换成私有image

部署启动

cd $HOME/go/src/github.com/kubernetes-incubator/external-storage/ceph/rbd/deploy
NAMESPACE=ceph # change this if you want to deploy it in another namespace
sed -r -i "s/namespace: [^ ]+/namespace: $NAMESPACE/g" ./rbac/clusterrolebinding.yaml ./rbac/rolebinding.yaml
kubectl -n $NAMESPACE apply -f ./rbac

3.4 创建动态卷和应用

cd /tmp

vim rbd-class.yaml

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: ceph-rbd
provisioner: ceph.com/rbd
#provisioner: kubernetes.io/rbd
parameters:
  #monitors: 192.168.105.92:6789,192.168.105.93:6789,192.168.105.94:6789
  monitors: ceph-mon-1.ceph.svc.cluster.local.:6789,ceph-mon-2.ceph.svc.cluster.local.:6789,ceph-mon-3.ceph.svc.cluster.local.:6789  # 为什么使用这个域名，请看下文4.2
  pool: kube
  adminId: admin
  #adminSecretNamespace: kube-system
  adminSecretName: ceph-admin-secret
  userId: kube
  userSecretNamespace: kube-system
  userSecretName: ceph-secret
  fsType: ext4
  imageFormat: "2"
  imageFeatures: layering

vim rbd-claim.yaml

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: rbd-pv-claim2
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: ceph-rbd
  resources:
    requests:
      storage: 1Gi

vim rbd-nginx-dy.yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx-rbd-dy
spec:
  replicas: 1
  template:
    metadata:
      labels:
        name: nginx
    spec:
      containers:
        - name: nginx
          image: nginx
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 80
          volumeMounts:
            - name: ceph-cephfs-volume
              mountPath: "/usr/share/nginx/html"
      volumes:
      - name: ceph-cephfs-volume
        persistentVolumeClaim:
          claimName: rbd-pv-claim2

kubectl create -f rbd-class.yaml
kubectl create -f rbd-claim.yaml
kubectl create -f rbd-nginx-dy.yaml                                         

结果验证：

[root@lab1 examples]# kubectl get pvc
NAME               STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
cephfs-pv-claim1   Bound     cephfs-pv1                                 1Gi        RWX                           1d
cephfs-pv-claim2   Bound     pvc-b535d9b6-a5b7-11e8-b4fa-000c2931d938   2Gi        RWX            cephfs         23h
rbd-pv-claim1      Bound     rbd-pv1                                    2Gi        RWO                           1d
rbd-pv-claim2      Bound     pvc-3780c9bb-a67e-11e8-a720-000c293d66a5   1Gi        RWO            ceph-rbd       1m
[root@lab1 examples]# kubectl get pod
NAME                                READY     STATUS    RESTARTS   AGE
curl-87b54756-zkp68                 1/1       Running   0          1d
nginx-cephfs-7777495b9b-wshjh       1/1       Running   0          1d
nginx-cephfs-dy-86bdbfd977-zwqrb    1/1       Running   0          23h
nginx-deployment-7f46fc97b9-qmttl   1/1       Running   2          2d
nginx-deployment-7f46fc97b9-wg76n   1/1       Running   0          1d
nginx-rbd-6b555f58c9-nhnmh          1/1       Running   0          1d
nginx-rbd-dy-5fdb49fc9b-8jdkh       1/1       Running   0          1m
[root@lab1 examples]# kubectl exec -it nginx-rbd-dy-5fdb49fc9b-8jdkh -- df -h|grep nginx
/dev/rbd1            976M  2.6M  958M   1% /usr/share/nginx/html

4. 踩坑解决

上文是官方文档操作的正常步骤和结果。但是过程中，踩了几个坑，花了我不少时间。

4.1 cannot get secrets in the namespace “kube-system”

secret和provisioner不在同一个namespace中的话，获取secret权限不够。

问题记录：
https://github.com/kubernetes-incubator/external-storage/issues/942

使用cephfs和RBD的rbac都报了这个错。

E0820 09:41:25.984983       1 controller.go:722] error syncing claim "default/claim2": failed to provision volume with StorageClass "rbd": failed to get admin secret from ["kube-system"/"ceph-admin-secret"]: secrets "ceph-admin-secret" is forbidden: User "system:serviceaccount:default:rbd-provisioner" cannot get secrets in the namespace "kube-system"
I0820 09:41:25.984999       1 event.go:221] Event(v1.ObjectReference{Kind:"PersistentVolumeClaim", Namespace:"default", Name:"claim2", UID:"4a136790-a45a-11e8-ba76-000c29ea3e30", APIVersion:"v1", ResourceVersion:"4557080", FieldPath:""}): type: 'Warning' reason: 'ProvisioningFailed' failed to provision volume with StorageClass "rbd": failed to get admin secret from ["kube-system"/"ceph-admin-secret"]: secrets "ceph-admin-secret" is forbidden: User "system:serviceaccount:default:rbd-provisioner" cannot get secrets in the namespace "kube-system"

解决之道：

以下文件添加secrets的权限：

external-storage/ceph/cephfs/deploy/rbac/clusterrole.yaml
external-storage/ceph/rbd/deploy/rbac/clusterrole.yaml

  - apiGroups: [""]
    resources: ["secrets"]
    verbs: ["get", "create", "delete"]

4.2 rbd-provisioner: missing Ceph monitors

问题记录：
https://github.com/kubernetes-incubator/external-storage/issues/778

源码中，monitors需要k8s dns解析，我这里使用外部ceph，肯定没有相关解析。所以手动添加解析。而且storageclass配置默认不支持直接修改（只能删除再添加），维护解析比维护storageclass配置要好些。

vim rbd-monitor-dns.yaml

kind: Service
apiVersion: v1
metadata:
  name: ceph-mon-1
  namespace: ceph
spec:
  type: ExternalName
  externalName: 192.168.105.92.xip.io
---
kind: Service
apiVersion: v1
metadata:
  name: ceph-mon-2
  namespace: ceph
spec:
  type: ExternalName
  externalName: 192.168.105.93.xip.io
---
kind: Service
apiVersion: v1
metadata:
  name: ceph-mon-3
  namespace: ceph
spec:
  type: ExternalName
  externalName: 192.168.105.94.xip.io

kubectl create -f rbd-monitor-dns.yaml

[root@lab1 ~]# kubectl get svc -n ceph
NAME         TYPE           CLUSTER-IP   EXTERNAL-IP             PORT(S)   AGE
ceph-mon-1   ExternalName   <none>       192.168.105.92.xip.io   <none>    5h
ceph-mon-2   ExternalName   <none>       192.168.105.93.xip.io   <none>    5h
ceph-mon-3   ExternalName   <none>       192.168.105.94.xip.io   <none>    5h

5. 小结

CephFS支持ReadWriteOnce、ReadOnlyMany和ReadWriteMany，可以允许多POD同时读写，适用于数据共享场景；Ceph RBD 只支持ReadWriteOnce和ReadOnlyMany，允许多POD同时读，适用于状态应用资源隔离场景。

参考资料：
[1] https://github.com/kubernetes-incubator/external-storage/tree/master/ceph
[2] https://kubernetes.io/docs/concepts/storage/storage-classes/
[3] https://kubernetes.io/docs/concepts/storage/persistent-volumes/