k8s pv 和 PVC 为何绑定不上
使用statefuset 部署有状态应用，应用总是处于pending 状态,在开始之前先介绍什么是statefuset, 在 k8s 中一般用 deployment 管理无状态应用，statefuset 用来管理有状态应用，如 redis 、mysql 、zookper 等分布式应用，这些应用的启动停止都会有严格的顺序
一、statefulset
headless (无头服务),没有cluserIP, 资源标识符，用于生成可解析的dns 记录
StatefulSet 用于pod 资源的管理
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volumeClaimTemplates 提供存储
二、statefulset 部署
使用nfs 做网络存储
搭建nfs
配置共享存储目录
创建pv
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编排 yaml
搭建nfs
yum install nfs-utils -y
mkdir -p /usr/local/k8s/redis/pv{7..12} # 创建挂载目录
cat /etc/exports /usr/local/k8s/redis/pv7 172.16.0.0/16(rw,sync,no_root_squash) /usr/local/k8s/redis/pv8 172.16.0.0/16(rw,sync,no_root_squash) /usr/local/k8s/redis/pv9 172.16.0.0/16(rw,sync,no_root_squash) /usr/local/k8s/redis/pv10 172.16.0.0/16(rw,sync,no_root_squash) /usr/local/k8s/redis/pv11 172.16.0.0/16(rw,sync,no_root_squash exportfs -avr
创建pv
cat nfs_pv2.yaml
apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv7 spec: capacity: storage: 500M accessModes: - ReadWriteMany persistentVolumeReclaimPolicy: Retain storageClassName: slow nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv7" --- apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv8 spec: capacity: storage: 500M accessModes: - ReadWriteMany storageClassName: slow persistentVolumeReclaimPolicy: Retain nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv8" --- apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv9 spec: capacity: storage: 500M accessModes: - ReadWriteMany storageClassName: slow persistentVolumeReclaimPolicy: Retain nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv9" --- apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv10 spec: capacity: storage: 500M accessModes: - ReadWriteMany storageClassName: slow persistentVolumeReclaimPolicy: Retain nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv10" --- apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv11 spec: capacity: storage: 500M accessModes: - ReadWriteMany storageClassName: slow persistentVolumeReclaimPolicy: Retain nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv11" --- apiVersion: v1 kind: PersistentVolume metadata: name: nfs-pv12 spec: capacity: storage: 500M accessModes: - ReadWriteMany storageClassName: slow persistentVolumeReclaimPolicy: Retain nfs: server: 172.16.0.59 path: "/usr/local/k8s/redis/pv12"
kubectl apply -f nfs_pv2.yaml
查看 # 创建成功
编写yaml 编排应用
apiVersion: v1 kind: Service metadata: name: myapp labels: app: myapp spec: ports: - port: 80 name: web clusterIP: None selector: app: myapp-pod --- apiVersion: apps/v1 kind: StatefulSet metadata: name: myapp spec: serviceName: myapp replicas: 3 selector: matchLabels: app: myapp-pod template: metadata: labels: app: myapp-pod spec: containers: - name: myapp image: ikubernetes/myapp:v1 resources: requests: cpu: "500m" memory: "500Mi" ports: - containerPort: 80 name: web volumeMounts: - name: myappdata mountPath: /usr/share/nginx/html volumeClaimTemplates: - metadata: name: myappdata spec: accessModes: ["ReadWriteOnce"] storageClassName: "slow" resources: requests: storage: 400Mi
kubectl create -f new-stateful.yaml
查看headless 创建成功
查看pod 是否创建成功
查看pvc 是否创建成功
pod 启动没有成功，依赖于pvc ，查看pvc 的日志,没有找到对应的pvc,明明写了啊
查看 关联信息，有下面这个属性
storageClassName: "slow"
三、statefulset 排障
pvc 无法创建，导致pod 无法正常启动，yaml 文件重新检查了几遍，
思考的方向：pvc 如何绑定pv ，通过storageClassName 去关联，pv 也创建成功了，也存在storageClassName: slow 这个属性，结果愣是找不到
。。。。
。。。。
后面检查pv 和pvc 的权限是否一直
发现pv 设置的权限
volumeClaimTemplates: 声明的pvc 权限
两边的权限不一致，
操作
删除 pvc kubectl delete pvc myappdata-myapp-0 -n daemon
删除 yaml 文件， kubectl delete -f new-stateful.yaml -n daemon
尝试修改 accessModes: ["ReadWriteMany"]
再次查看
提示：pv 和PVC 设定权限注
四、statefulset 测试，域名解析
kubectl exec -it myapp-0 sh -n daemon
nslookup myapp-0.myapp.daemon.svc.cluster.local
解析的规则 如下
myapp-0 myapp daemon
FQDN： $(podname).(headless server name).namespace.svc.cluster.local
容器里面如没有nsllokup ,需要安装对应的包，busybox 可以提供类似的功能
提供yaml 文件
apiVersion: v1 kind: Pod metadata: name: busybox namespace: daemon spec: containers: - name: busybox image: busybox:1.28.4 command: - sleep - "7600" resources: requests: memory: "200Mi" cpu: "250m" imagePullPolicy: IfNotPresent restartPolicy: Never
五、statefulset 的扩缩容
扩容：
Statefulset 资源的扩缩容与Deployment 资源相似，即通过修改副本数,Statefulset 资源的拓展过程，与创建过程类似，应用名称的索引号，依次增加
可使用 kubectl scale
kubectl patch
实践：kubectl scale statefulset myapp --replicas=4
缩容：
缩容只需要将pod 副本数调小
kubectl patch statefulset myapp -p '{"spec":{"replicas":3}}' -n daemon
提示：资源扩缩容，需要动态创建pv 与pvc 的绑定关系，这里使用的是nfs 做持久化存储，pv 的多少是预先创建的
六、statefulset 的滚动更新
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滚动更新
金丝雀发布
滚动更新
滚动更新 是从索引pod 号最大的开始的，终止完一个资源，在进行开始下一个pod ，滚动更新是 statefulset 默认的更新策略
kubectl set image statefulset/myapp myapp=ikubernetes/myapp:v2 -n daemon
升级过程
查看pod 状态
kubectl get pods -n daemon
查看升级后镜像是否更新
kubectl describe pod myapp-0 -n daemon