k8s实践18:statefulset学习配置记录

Posted 2022-05-12

1.
基础概念

statefulset,可以翻译成有状态的设定.

和deployment的对比

deployment部署创建的pod是无状态的,重新调度pod,pod名字hostname,启动pod顺序删除pod顺序都是随机的.deployment使用的是共享存储,所有pod共用一个存储卷.

statefulset部署创建的pod是有状态的,重新调度pod,pod名字hostname保持固定不变,启动pod顺序删除pod顺序都可以根据定义的顺序有序执行操作,有序的动态更新,statefulset使用的存储,不是共用一个存储卷,一个pod对应一个存储卷(pv).pod重新创建调度挂载的存储卷保持不变.

2.
statefulset实现用到的技术概念

headless service
headless service不需要配置clusterIP,对应的每一个pod都会有相应的dns域名.因此可以为每个pod生成可解析的dns记录.

statefulset
statefulset 用来部署管理pod资源

volumeClaimTemplates
实现每个pod对应一个pv存储卷

3.
测试环境准备

kubernets集群必须部署dns,能正常解析.
kubernetes集群必须配置storageclass,能够实现动态创建pv.
我这里用的是nfs存储环境.

4.
headless service和service解析对比

service

[root@k8s-master1 ~]# kubectl get svc
NAME? ? ? ?? TYPE? ? ? ? CLUSTER-IP? ? ? EXTERNAL-IP?? PORT(S)? ? ?? AGE
httpd-svc? ? NodePort? ? 10.254.33.250?? <none>? ? ? ? 80:8768/TCP?? 92d
kubernetes?? ClusterIP?? 10.254.0.1? ? ? <none>? ? ? ? 443/TCP? ? ?? 92d

注意下面解析用到dns的ip

[root@k8s-master1 ~]# kubectl get svc -n kube-system
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TYPE? ? ? ? CLUSTER-IP? ? ?? EXTERNAL-IP?? PORT(S)? ? ? ? ? ? ? ? ?? AGE
kube-dns? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ClusterIP?? 10.254.0.2? ? ?? <none>? ? ? ? 53/UDP,53/TCP? ? ? ? ? ?? 92d

[root@k8s-master1 ~]# kubectl describe svc httpd-svc
Name:? ? ? ? ? ? ? ? ? ?? httpd-svc
Namespace:? ? ? ? ? ? ? ? default
Labels:? ? ? ? ? ? ? ? ?? <none>
Annotations:? ? ? ? ? ? ? kubectl.kubernetes.io/last-applied-configuration="apiVersion":"v1","kind":"Service","metadata":"annotations":,"name":"httpd-svc","namespace":"default","spec":"ports":["port":80],"selector":"a...
Selector:? ? ? ? ? ? ? ?? app=httpd-app
Type:? ? ? ? ? ? ? ? ? ?? NodePort
IP:? ? ? ? ? ? ? ? ? ? ?? 10.254.33.250
Port:? ? ? ? ? ? ? ? ? ?? <unset>? 80/TCP
TargetPort:? ? ? ? ? ? ?? 80/TCP
NodePort:? ? ? ? ? ? ? ?? <unset>? 8768/TCP
Endpoints:? ? ? ? ? ? ? ? 172.30.37.7:80
Session Affinity:? ? ? ?? None
External Traffic Policy:? Cluster
Events:? ? ? ? ? ? ? ? ?? <none>
[root@k8s-master1 ~]#

随便进个namespace是default的pod用nslookup解析

[root@k8s-master1 ~]# kubectl exec -it nfs-client-provisioner-65bf6bd464-qdzcj nslookup httpd-svc.default.svc.cluster.local 10.254.0.2
Server:? ? 10.254.0.2
Address 1: 10.254.0.2 kube-dns.kube-system.svc.cluster.local

Name:? ? ? httpd-svc.default.svc.cluster.local
Address 1: 10.254.33.250 httpd-svc.default.svc.cluster.local
[root@k8s-master1 ~]#

headless service

[root@k8s-master1 test]# cat headless-svc-test.yaml
apiVersion: v1
kind: Service
metadata:
? name: headless-svc
? labels:
? ? app: headless-svc
spec:
? ports:
? - port: 80
? ? name: myweb
? selector:
? ? app: headless-pod
? clusterIP: None

---
apiVersion: apps/v1
kind: Deployment
metadata:
? name: headless-test
spec:
? replicas: 3
? selector:
? ? matchLabels:
? ? ? app: headless-pod
? template:
? ? metadata:
? ? ? labels:
? ? ? ? app: headless-pod
? ? spec:
? ? ? containers:
? ? ? - image: httpd
? ? ? ? name: myhttpd
? ? ? ? ports:
? ? ? ? - containerPort: 80
[root@k8s-master1 test]#

[root@k8s-master1 test]# kubectl describe svc headless-svc
Name:? ? ? ? ? ? ? headless-svc
Namespace:? ? ? ?? default
Labels:? ? ? ? ? ? app=headless-svc
Annotations:? ? ?? kubectl.kubernetes.io/last-applied-configuration="apiVersion":"v1","kind":"Service","metadata":"annotations":,"labels":"app":"headless-svc","name":"headless-svc","namespace":"default","spec":"...
Selector:? ? ? ? ? app=headless-pod
Type:? ? ? ? ? ? ? ClusterIP
IP:? ? ? ? ? ? ? ? None
Port:? ? ? ? ? ? ? myweb? 80/TCP
TargetPort:? ? ? ? 80/TCP
Endpoints:? ? ? ?? 172.30.65.4:80,172.30.65.5:80,172.30.81.6:80
Session Affinity:? None
Events:? ? ? ? ? ? <none>
[root@k8s-master1 test]#

随便进个namespace是default的pod用nslookup解析

[root@k8s-master1 test]# kubectl exec -it nfs-client-provisioner-65bf6bd464-qdzcj nslookup headless-svc.default.svc.cluster.local 10.254.0.2
Server:? ? 10.254.0.2
Address 1: 10.254.0.2 kube-dns.kube-system.svc.cluster.local

Name:? ? ? headless-svc.default.svc.cluster.local
Address 1: 172.30.65.5 172-30-65-5.headless-svc.default.svc.cluster.local
Address 2: 172.30.65.4 172-30-65-4.headless-svc.default.svc.cluster.local
Address 3: 172.30.81.6 172-30-81-6.headless-svc.default.svc.cluster.local
[root@k8s-master1 test]#

对比可知:
配置headless service 和service的区别只是加一个clusterIP: None

dns解析的不同
service 解析返回svc的ip和dns域名
headless service 解析返回pod的ip和dns域名

headless service解析能够返回pod的hostname.
statefulset需要固定pod name,hostname,必须要能解析pod的hostname.因此使用headless service.

5.
statefulset配置测试

[root@k8s-master1 test]# cat statefulset-test.yaml
apiVersion: v1
kind: Service
metadata:
? name: headless-svc
? labels:
? ? app: headless-svc
spec:
? ports:
? - port: 80
? ? name: myweb
? selector:
? ? app: headless-pod
? clusterIP: None

---
apiVersion: apps/v1
kind: StatefulSet
metadata:
? name: statefulset-test
spec:
? serviceName: headless-svc
? replicas: 3
? selector:
? ? matchLabels:
? ? ? app: headless-pod
? template:
? ? metadata:
? ? ? labels:
? ? ? ? app: headless-pod
? ? spec:
? ? ? containers:
? ? ? - image: httpd
? ? ? ? name: myhttpd
? ? ? ? ports:
? ? ? ? - containerPort: 80
? ? ? ? ? name: httpd
[root@k8s-master1 test]#

[root@k8s-master1 test]# kubectl describe svc headless-svc
Name:? ? ? ? ? ? ? headless-svc
Namespace:? ? ? ?? default
Labels:? ? ? ? ? ? app=headless-svc
Annotations:? ? ?? kubectl.kubernetes.io/last-applied-configuration="apiVersion":"v1","kind":"Service","metadata":"annotations":,"labels":"app":"headless-svc","name":"headless-svc","namespace":"default","spec":"...
Selector:? ? ? ? ? app=headless-pod
Type:? ? ? ? ? ? ? ClusterIP
IP:? ? ? ? ? ? ? ? None
Port:? ? ? ? ? ? ? myweb? 80/TCP
TargetPort:? ? ? ? 80/TCP
Endpoints:? ? ? ?? 172.30.65.4:80,172.30.65.5:80,172.30.81.6:80
Session Affinity:? None
Events:? ? ? ? ? ? <none>

[root@k8s-master1 test]# kubectl get pod -o wide
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ?? STATUS? ? RESTARTS?? AGE? ? ?? IP? ? ? ? ? ? NODE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running?? 0? ? ? ? ? 4m? ? ? ? 172.30.65.4?? k8s-master3
statefulset-test-1? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running?? 0? ? ? ? ? 4m? ? ? ? 172.30.81.6?? k8s-master2
statefulset-test-2? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running?? 0? ? ? ? ? 4m? ? ? ? 172.30.65.5?? k8s-master3

hostname
[root@k8s-master1 test]# kubectl exec -it statefulset-test-0 hostname
statefulset-test-0
[root@k8s-master1 test]# kubectl exec -it statefulset-test-1 hostname
statefulset-test-1
[root@k8s-master1 test]# kubectl exec -it statefulset-test-2 hostname
statefulset-test-2

解析

[root@k8s-master1 test]# kubectl exec -it nfs-client-provisioner-65bf6bd464-qdzcj nslookup headless-svc.default.svc.cluster.local 10.254.0.2
Server:? ? 10.254.0.2
Address 1: 10.254.0.2 kube-dns.kube-system.svc.cluster.local

Name:? ? ? headless-svc.default.svc.cluster.local
Address 1: 172.30.65.5 statefulset-test-2.headless-svc.default.svc.cluster.local
Address 2: 172.30.65.4 statefulset-test-0.headless-svc.default.svc.cluster.local
Address 3: 172.30.81.6 statefulset-test-1.headless-svc.default.svc.cluster.local
[root@k8s-master1 test]#

statefulset部署和上面的head services使用deployment部署对比
pod名字是按照顺序生成,从0开始每次+1命名pod
创建pod,也是按照顺序一个一个创建,没有像deployment部署那样批量一次性全部创建.

测试

删除pod

[root@k8s-master1 test]# kubectl delete pod statefulset-test-0
pod "statefulset-test-0" deleted

[root@k8s-master1 test]# kubectl get pod
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ?? STATUS? ? ? ? RESTARTS?? AGE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 0/1? ? ?? Terminating?? 0? ? ? ? ? 19m
statefulset-test-1? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running? ? ?? 0? ? ? ? ? 19m
statefulset-test-2? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running? ? ?? 0? ? ? ? ? 19m

重新自动创建pod

[root@k8s-master1 test]# kubectl get pod
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ?? STATUS? ? ? ? ? ? ? RESTARTS?? AGE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 0/1? ? ?? ContainerCreating?? 0? ? ? ? ? 0s
statefulset-test-1? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running? ? ? ? ? ?? 0? ? ? ? ? 19m
statefulset-test-2? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running? ? ? ? ? ?? 0? ? ? ? ? 19m

[root@k8s-master1 test]# kubectl get pod
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ?? STATUS? ? RESTARTS?? AGE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running?? 0? ? ? ? ? 4s
statefulset-test-1? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running?? 0? ? ? ? ? 20m
statefulset-test-2? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running?? 0? ? ? ? ? 19m

[root@k8s-master1 test]# kubectl exec -it? statefulset-test-0 hostname
statefulset-test-0
[root@k8s-master1 test]#

可见重新创建pod,pod的名字和hostname没有改变.

把replicas改成1

[root@k8s-master1 test]# kubectl apply -f statefulset-test.yaml
service "headless-svc" unchanged
statefulset.apps "statefulset-test" configured
[root@k8s-master1 test]# kubectl get pod
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ?? STATUS? ? ? ? RESTARTS?? AGE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running? ? ?? 0? ? ? ? ? 4m
statefulset-test-1? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running? ? ?? 0? ? ? ? ? 24m
statefulset-test-2? ? ? ? ? ? ? ? ? ? ? ? 0/1? ? ?? Terminating?? 0? ? ? ? ? 24m
[root@k8s-master1 test]# kubectl get pod
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ?? STATUS? ? ? ? RESTARTS?? AGE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running? ? ?? 0? ? ? ? ? 4m
statefulset-test-1? ? ? ? ? ? ? ? ? ? ? ? 0/1? ? ?? Terminating?? 0? ? ? ? ? 24m
[root@k8s-master1 test]# kubectl get pod
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ?? STATUS? ? RESTARTS?? AGE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running?? 0? ? ? ? ? 5m

pod按照顺序一个一个删除

把replicas改回3

[root@k8s-master1 test]# kubectl apply -f statefulset-test.yaml
service "headless-svc" unchanged
statefulset.apps "statefulset-test" configured
[root@k8s-master1 test]# kubectl get pod
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ?? STATUS? ? ? ? ? ? ? RESTARTS?? AGE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running? ? ? ? ? ?? 0? ? ? ? ? 6m
statefulset-test-1? ? ? ? ? ? ? ? ? ? ? ? 0/1? ? ?? ContainerCreating?? 0? ? ? ? ? 4s
[root@k8s-master1 test]# kubectl get pod
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ?? STATUS? ? ? ? ? ? ? RESTARTS?? AGE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running? ? ? ? ? ?? 0? ? ? ? ? 6m
statefulset-test-1? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running? ? ? ? ? ?? 0? ? ? ? ? 8s
statefulset-test-2? ? ? ? ? ? ? ? ? ? ? ? 0/1? ? ?? ContainerCreating?? 0? ? ? ? ? 1s
[root@k8s-master1 test]# kubectl get pod
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ?? STATUS? ? RESTARTS?? AGE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running?? 0? ? ? ? ? 6m
statefulset-test-1? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running?? 0? ? ? ? ? 14s
statefulset-test-2? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ?? Running?? 0? ? ? ? ? 7s
[root@k8s-master1 test]#
[root@k8s-master1 test]# kubectl exec -it statefulset-test-2 hostname
statefulset-test-2
[root@k8s-master1 test]#

pod按照顺序顺序一个一个创建,并且pod名字和hostname没有改变

6.
statefulset结合volumeClaimTemplates测试

[root@k8s-master1 test]# cat statefulset-test.yaml
apiVersion: v1
kind: Service
metadata:
? name: headless-svc
? labels:
? ? app: headless-svc
spec:
? ports:
? - port: 80
? ? name: myweb
? selector:
? ? app: headless-pod
? clusterIP: None

---
apiVersion: apps/v1
kind: StatefulSet
metadata:
? name: statefulset-test
spec:
? serviceName: headless-svc
? replicas: 3
? selector:
? ? matchLabels:
? ? ? app: headless-pod
? template:
? ? metadata:
? ? ? labels:
? ? ? ? app: headless-pod
? ? spec:
? ? ? containers:
? ? ? - image: httpd
? ? ? ? name: myhttpd
? ? ? ? ports:
? ? ? ? - containerPort: 80
? ? ? ? ? name: httpd
? ? ? ? volumeMounts:
? ? ? ? - mountPath: /mnt
? ? ? ? ? name: test
? volumeClaimTemplates:
? - metadata:
? ? ? name: test
? ? ? annotations:
? ? ? ? volume.beta.kubernetes.io/storage-class: managed-nfs-storage
? ? spec:
? ? ? accessModes: [ "ReadWriteOnce" ]
? ? ? resources:
? ? ? ? requests:
? ? ? ? ? storage: 100Mi

注意格式,多个空格少个空格都会失败.

annotations:
? ? ? ? volume.beta.kubernetes.io/storage-class: managed-nfs-storage

这是指定storageclass

[root@k8s-master1 test]# kubectl get pv,pvc
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? CAPACITY? ACCESS MODES? RECLAIM POLICY? STATUS? ? CLAIM? ? ? ? ? ? ? ? ? ? ? ? ? ? STORAGECLASS? ? ? ? ? REASON? ? AGE
persistentvolume/pvc-a1c6928d-aebc-11e9-8580-000c291d7023? 100Mi? ? ? RWO? ? ? ? ? ? Delete? ? ? ? ? Bound? ? default/test-statefulset-test-0? managed-nfs-storage? ? ? ? ? ? 1m
persistentvolume/pvc-a94813df-aebc-11e9-8580-000c291d7023? 100Mi? ? ? RWO? ? ? ? ? ? Delete? ? ? ? ? Bound? ? default/test-statefulset-test-1? managed-nfs-storage? ? ? ? ? ? 1m
persistentvolume/pvc-b234f5a7-aebc-11e9-8580-000c291d7023? 100Mi? ? ? RWO? ? ? ? ? ? Delete? ? ? ? ? Bound? ? default/test-statefulset-test-2? managed-nfs-storage? ? ? ? ? ? 49s

NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? STATUS? ? VOLUME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? CAPACITY? ACCESS MODES? STORAGECLASS? ? ? ? ? AGE
persistentvolumeclaim/test-statefulset-test-0? Bound? ? pvc-a1c6928d-aebc-11e9-8580-000c291d7023? 100Mi? ? ? RWO? ? ? ? ? ? managed-nfs-storage? 1m
persistentvolumeclaim/test-statefulset-test-1? Bound? ? pvc-a94813df-aebc-11e9-8580-000c291d7023? 100Mi? ? ? RWO? ? ? ? ? ? managed-nfs-storage? 1m
persistentvolumeclaim/test-statefulset-test-2? Bound? ? pvc-b234f5a7-aebc-11e9-8580-000c291d7023? 100Mi? ? ? RWO? ? ? ? ? ? managed-nfs-storage? 1m
[root@k8s-master1 test]#

检索pod对应的pv卷,截取volumes部分对比

[root@k8s-master1 test]# kubectl describe pod statefulset-test-0
Name:? ? ? ? ? ? ? statefulset-test-0
Namespace:? ? ? ? ? default
Volumes:
? test:
? ? Type:? ? ? PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
? ? ClaimName:? test-statefulset-test-0
? ? ReadOnly:? false

[root@k8s-master1 test]# kubectl describe pod statefulset-test-1
Name:? ? ? ? ? ? ? statefulset-test-1
Namespace:? ? ? ? ? default
Volumes:
? test:
? ? Type:? ? ? PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
? ? ClaimName:? test-statefulset-test-1
? ? ReadOnly:? false

[root@k8s-master1 test]# kubectl describe pod statefulset-test-2
Name:? ? ? ? ? ? ? statefulset-test-2
Namespace:? ? ? ? ? default
Volumes:
? test:
? ? Type:? ? ? PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
? ? ClaimName:? test-statefulset-test-2
? ? ReadOnly:? false

可以看到一个pod对应使用了一个pv卷.

检索nfs server存取目录,可以看到新建的pvc目录

[root@k8s-master3 k8s]# ls
default-test-statefulset-test-0-pvc-a1c6928d-aebc-11e9-8580-000c291d7023
default-test-statefulset-test-1-pvc-a94813df-aebc-11e9-8580-000c291d7023
default-test-statefulset-test-2-pvc-b234f5a7-aebc-11e9-8580-000c291d7023
[root@k8s-master3 k8s]#

测试

删除pod,看看能重新对应原来的pvc卷吗？

[root@k8s-master1 test]# kubectl get pod
NAME? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? READY? ? STATUS? ? RESTARTS? AGE
statefulset-test-0? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ? Running? 0? ? ? ? ? 12m
statefulset-test-1? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ? Running? 0? ? ? ? ? 11m
statefulset-test-2? ? ? ? ? ? ? ? ? ? ? ? 1/1? ? ? Running? 0? ? ? ? ? 11m

在statefulset-test-1和statefulset-test-2? 新建个文件存储在pvc

[root@k8s-master1 test]# kubectl exec -it statefulset-test-1 touch /mnt/t1
[root@k8s-master1 test]# kubectl exec -it statefulset-test-2 touch /mnt/t2

检索pvc卷

[root@k8s-master3 k8s]# cd default-test-statefulset-test-1-pvc-a94813df-aebc-11e9-8580-000c291d7023/
[root@k8s-master3 default-test-statefulset-test-1-pvc-a94813df-aebc-11e9-8580-000c291d7023]# ls
t1
[root@k8s-master3 default-test-statefulset-test-1-pvc-a94813df-aebc-11e9-8580-000c291d7023]# cd ..
[root@k8s-master3 k8s]# cd default-test-statefulset-test-2-pvc-b234f5a7-aebc-11e9-8580-000c291d7023/
[root@k8s-master3 default-test-statefulset-test-2-pvc-b234f5a7-aebc-11e9-8580-000c291d7023]# ls
t2

删除这两个pod

[root@k8s-master1 test]# kubectl delete pod statefulset-test-1 statefulset-test-2
pod "statefulset-test-1" deleted
pod "statefulset-test-2" deleted

删除后,pod自动创建创建
再检索重新创建的pod

[root@k8s-master1 test]# kubectl describe pod statefulset-test-1
Name:? ? ? ? ? ? ? statefulset-test-1
Namespace:? ? ? ? ? default
Volumes:
? test:
? ? Type:? ? ? PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
? ? ClaimName:? test-statefulset-test-1
? ? ReadOnly:? false

[root@k8s-master1 test]# kubectl describe pod statefulset-test-2
Name:? ? ? ? ? ? ? statefulset-test-2
Namespace:? ? ? ? ? default
Volumes:
? test:
? ? Type:? ? ? PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
? ? ClaimName:? test-statefulset-test-2
? ? ReadOnly:? false

可以看到pod命令hostname和存储卷全部都和删除前保持一样.

[root@k8s-master1 test]# kubectl exec -it statefulset-test-1 ls /mnt
t1
[root@k8s-master1 test]# kubectl exec -it statefulset-test-2 ls /mnt
t2
[root@k8s-master1 test]#

前面创建的保存在存储卷的文件也保持不变.

7.
留下的一个疑问:
deployment部署,svc通过kube-proxy结合ipvs和iptables实现访问后端pod.
statefulset部署,svc是如何实现访问后端pod呢?规则是什么?