kubernetes-控制器statefulset和Job（十三）
时间:2022-07-26
本文章向大家介绍kubernetes-控制器statefulset和Job（十三），主要内容包括其使用实例、应用技巧、基本知识点总结和需要注意事项，具有一定的参考价值，需要的朋友可以参考一下。
从前面的学习我们知道使用Deployment创建的pod是无状态的，当挂载了Volume之后，如果该pod挂了，Replication Controller会再启动一个pod来保证可用性，但是由于pod是无状态的，pod挂了就会和之前的Volume的关系断开，新创建的Pod无法找到之前的Pod。但是对于用户而言，他们对底层的Pod挂了是没有感知的，但是当Pod挂了之后就无法再使用之前挂载的存储卷。 为了解决这一问题，就引入了StatefulSet用于保留Pod的状态信息。 StatefulSet是为了解决有状态服务的问题（对应Deployments和ReplicaSets是为无状态服务而设计），其应用场景包括：
- 1、稳定的持久化存储，即Pod重新调度后还是能访问到相同的持久化数据，基于PVC来实现
- 2、稳定的网络标志，即Pod重新调度后其PodName和HostName不变，基于Headless Service（即没有Cluster IP的Service）来实现
- 3、有序部署，有序扩展，即Pod是有顺序的，在部署或者扩展的时候要依据定义的顺序依次依次进行（即从0到N-1，在下一个Pod运行之前所有之前的Pod必须都是Running和Ready状态），基于init containers来实现
- 4、有序收缩，有序删除（即从N-1到0）
- 5、有序的滚动更新
参考：https://kubernetes.io/docs/tutorials/stateful-application/basic-stateful-set/
创建statefulSet示例
[root@k8s-master1 volume]# cat nginx-demo.yaml
apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
app: nginx
spec:
ports:
- port: 80
name: web
clusterIP: None
selector:
app: nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: web
spec:
selector:
matchLabels:
app: nginx
serviceName: "nginx"
replicas: 3
template:
metadata:
labels:
app: nginx
spec:
terminationGracePeriodSeconds: 10
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
name: web
volumeMounts:
- name: www
mountPath: /usr/share/nginx/html
volumeClaimTemplates:
- metadata:
name: www
spec:
accessModes: [ "ReadWriteOnce" ]
storageClassName: "managed-nfs-storage"
resources:
requests:
storage: 1Gi
[root@k8s-master1 volume]# kubectl apply -f nginx-demo.yaml
service/nginx created
statefulset.apps/web created
[root@k8s-master1 volume]# kubectl get svc,sts #查看无头服务，svc的CLUSTER—IP为None
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 9d
service/nginx ClusterIP None <none> 80/TCP 13s
NAME READY AGE
statefulset.apps/web 1/3 13s
[root@k8s-master1 volume]# kubectl get pv,pvc #查看pv动态供给
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
persistentvolume/default-www-web-0-pvc-7fe5d833-0a44-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-0 managed-nfs-storage 18s
persistentvolume/default-www-web-1-pvc-85d17f15-0a44-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-1 managed-nfs-storage 14s
persistentvolume/default-www-web-2-pvc-8aa41937-0a44-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-2 managed-nfs-storage 6s
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
persistentvolumeclaim/www-web-0 Bound default-www-web-0-pvc-7fe5d833-0a44-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 24s
persistentvolumeclaim/www-web-1 Bound default-www-web-1-pvc-85d17f15-0a44-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 14s
persistentvolumeclaim/www-web-2 Bound default-www-web-2-pvc-8aa41937-0a44-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 6s
[root@k8s-master1 volume]# kubectl get pod #查看pod
NAME READY STATUS RESTARTS AGE
nfs-client-provisioner-f69cd5cf-rfbdb 1/1 Running 0 2m16s
web-0 1/1 Running 0 33s
web-1 1/1 Running 0 23s
web-2 1/1 Running 0 15s删除statefulSet，PVC依旧存在的，再重新创建pod时，依旧会重新去绑定原来的pvc
[root@k8s-master1 volume]# kubectl delete -f nginx-demo.yaml
service "nginx" deleted
statefulset.apps "web" deleted
[root@k8s-master1 volume]# kubectl get pods -w
NAME READY STATUS RESTARTS AGE
nfs-client-provisioner-f69cd5cf-rfbdb 1/1 Running 0 7m58s
web-0 0/1 Terminating 0 6m15s
web-1 0/1 Terminating 0 6m5s
web-2 0/1 Terminating 0 5m57s
web-0 0/1 Terminating 0 6m17s
web-0 0/1 Terminating 0 6m17s
web-2 0/1 Terminating 0 5m59s
web-2 0/1 Terminating 0 5m59s
web-1 0/1 Terminating 0 6m11s
web-1 0/1 Terminating 0 6m11s
[root@k8s-master1 volume]# kubectl apply -f nginx-demo.yaml
service/nginx created
statefulset.apps/web created
[root@k8s-master1 volume]# kubectl get pv,pvc
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
persistentvolume/default-www-web-0-pvc-7fe5d833-0a44-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-0 managed-nfs-storage 9m34s
persistentvolume/default-www-web-1-pvc-85d17f15-0a44-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-1 managed-nfs-storage 9m30s
persistentvolume/default-www-web-2-pvc-8aa41937-0a44-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-2 managed-nfs-storage 9m22s
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
persistentvolumeclaim/www-web-0 Bound default-www-web-0-pvc-7fe5d833-0a44-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 9m40s
persistentvolumeclaim/www-web-1 Bound default-www-web-1-pvc-85d17f15-0a44-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 9m30s
persistentvolumeclaim/www-web-2 Bound default-www-web-2-pvc-8aa41937-0a44-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 9m22s滚动更新
RollingUpdate 更新策略在 StatefulSet 中实现 Pod 的自动滚动更新。 当StatefulSet的 .spec.updateStrategy.type 设置为 RollingUpdate 时，默认为：RollingUpdate。StatefulSet 控制器将在 StatefulSet 中删除并重新创建每个 Pod。 它将以与 Pod 终止相同的顺序进行（从最大的序数到最小的序数），每次更新一个 Pod。 在更新其前身之前，它将等待正在更新的 Pod 状态变成正在运行并就绪。如下操作的滚动更新是有2-0的顺序更新。
[root@k8s-master1 volume]# vim nginx-demo.yaml
[root@k8s-master1 volume]# kubectl apply -f nginx-demo.yaml
service/nginx unchanged
statefulset.apps/web configured
[root@k8s-master1 volume]# kubectl get pods -w
NAME READY STATUS RESTARTS AGE
nfs-client-provisioner-f69cd5cf-rfbdb 1/1 Running 0 14m
web-0 1/1 Running 0 3m42s
web-1 1/1 Running 0 3m34s
web-2 0/1 Terminating 0 3m24s
web-2 0/1 Terminating 0 3m35s
web-2 0/1 Terminating 0 3m35s
web-2 0/1 Pending 0 0s
web-2 0/1 Pending 0 0s
web-2 0/1 ContainerCreating 0 0s
web-2 1/1 Running 0 7s
web-1 1/1 Terminating 0 3m52s
web-1 0/1 Terminating 0 3m53s
web-1 0/1 Terminating 0 3m54s
web-1 0/1 Terminating 0 3m54s
web-1 0/1 Pending 0 0s
web-1 0/1 Pending 0 0s
web-1 0/1 ContainerCreating 0 0s
web-1 1/1 Running 0 23s
web-0 1/1 Terminating 0 4m25s
web-0 0/1 Terminating 0 4m26s
web-0 0/1 Terminating 0 4m33s
web-0 0/1 Terminating 0 4m33s
web-0 0/1 Pending 0 0s
web-0 0/1 Pending 0 0s
web-0 0/1 ContainerCreating 0 0s
web-0 1/1 Running 0 4s扩展伸缩
[root@k8s-master1 volume]# kubectl scale sts web --replicas=5 #扩展到5个副本
statefulset.apps/web scaled
[root@k8s-master1 volume]# kubectl get pod -w #动态查看扩容
NAME READY STATUS RESTARTS AGE
nfs-client-provisioner-f69cd5cf-rfbdb 1/1 Running 0 25m
web-0 1/1 Running 0 9m40s
web-1 1/1 Running 0 10m
web-2 1/1 Running 0 10m
web-3 0/1 ContainerCreating 0 12s
web-3 1/1 Running 0 21s
web-4 0/1 Pending 0 0s
web-4 0/1 Pending 0 0s
web-4 0/1 Pending 0 1s
web-4 0/1 ContainerCreating 0 1s
web-4 1/1 Running 0 9s
[root@k8s-master1 volume]# kubectl get pv,pvc #查看pv绑定
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
persistentvolume/default-www-web-0-pvc-7fe5d833-0a44-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-0 managed-nfs-storage 25m
persistentvolume/default-www-web-1-pvc-85d17f15-0a44-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-1 managed-nfs-storage 25m
persistentvolume/default-www-web-2-pvc-8aa41937-0a44-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-2 managed-nfs-storage 25m
persistentvolume/default-www-web-3-pvc-c7efc39f-0a47-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-3 managed-nfs-storage 2m10s
persistentvolume/default-www-web-4-pvc-d498cf02-0a47-11e9-b58a-000c298a2b5f 1Gi RWO Delete Bound default/www-web-4 managed-nfs-storage 112s
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
persistentvolumeclaim/www-web-0 Bound default-www-web-0-pvc-7fe5d833-0a44-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 25m
persistentvolumeclaim/www-web-1 Bound default-www-web-1-pvc-85d17f15-0a44-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 25m
persistentvolumeclaim/www-web-2 Bound default-www-web-2-pvc-8aa41937-0a44-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 25m
persistentvolumeclaim/www-web-3 Bound default-www-web-3-pvc-c7efc39f-0a47-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 2m13s
persistentvolumeclaim/www-web-4 Bound default-www-web-4-pvc-d498cf02-0a47-11e9-b58a-000c298a2b5f 1Gi RWO managed-nfs-storage 112s
[root@k8s-master1 volume]# kubectl patch sts web -p '{"spec":{"replicas":2}}' #缩容到两个副本
statefulset.apps/web patched
[root@k8s-master1 volume]# kubectl get pod -w #动态查看缩容
NAME READY STATUS RESTARTS AGE
nfs-client-provisioner-f69cd5cf-rfbdb 1/1 Running 0 28m
web-0 1/1 Running 0 12m
web-1 1/1 Running 0 13m
web-2 1/1 Running 0 13m
web-3 1/1 Running 0 3m16s
web-4 0/1 Terminating 0 2m55s
web-4 0/1 Terminating 0 2m57s
web-4 0/1 Terminating 0 2m57s
web-3 1/1 Terminating 0 3m18s
web-3 0/1 Terminating 0 3m19s
web-3 0/1 Terminating 0 3m22s
web-3 0/1 Terminating 0 3m22s
web-2 1/1 Terminating 0 13m
web-2 0/1 Terminating 0 13m
web-2 0/1 Terminating 0 13m
web-2 0/1 Terminating 0 13m更新策略
[root@k8s-master1 volume]# kubectl patch sts web -p '{"spec":{"updateStrategy":{"rollingUpdate":{"partition":2}}}}'
statefulset.apps/web patched
[root@k8s-master1 volume]# kubectl describe sts web
Name: web
Namespace: default
CreationTimestamp: Fri, 28 Dec 2018 10:11:01 +0800
Selector: app=nginx
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"apps/v1","kind":"StatefulSet","metadata":{"annotations":{},"name":"web","namespace":"default"},"spec":{"replicas":3,"select...
Replicas: 824638349112 desired | 2 total
Update Strategy: RollingUpdate
Partition: 824638947612
Pods Status: 2 Running / 0 Waiting / 0 Succeeded / 0 Failed
。。。版本升级
[root@k8s-master1 volume]# kubectl get sts -o wide
NAME READY AGE CONTAINERS IMAGES
web 2/2 29m nginx nginx:1.14
[root@k8s-master1 volume]# kubectl set image sts/web nginx=nginx:1.15
statefulset.apps/web image updated
[root@k8s-master1 volume]# kubectl get sts -o wide
NAME READY AGE CONTAINERS IMAGES
web 2/2 32m nginx nginx:1.15headless service做dns解析是直接解析到pod的
[root@k8s-master1 volume]# kubectl get pod,svc -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod/nfs-client-provisioner-f69cd5cf-rfbdb 1/1 Running 0 74m 172.17.73.3 192.168.0.126 <none> <none>
pod/web-0 1/1 Running 0 59m 172.17.32.3 192.168.0.125 <none> <none>
pod/web-1 1/1 Running 0 59m 172.17.73.5 192.168.0.126 <none> <none>
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
service/kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 9d <none>
service/nginx ClusterIP None <none> 80/TCP 63m app=nginx
[root@k8s-master1 volume]# kubectl run -it --image=busybox:1.28.4 --rm --restart=Never sh
If you don't see a command prompt, try pressing enter.
/ # nslookup web-0.nginx
Server: 10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local
Name: web-0.nginx
Address 1: 172.17.32.3 web-0.nginx.default.svc.cluster.local
/ # nslookup web-1.nginx
Server: 10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local
Name: web-1.nginx
Address 1: 172.17.73.5 web-1.nginx.default.svc.cluster.localJOB
https://kubernetes.io/docs/concepts/workloads/controllers/jobs-run-to-completion/
Job分为普通任务（Job）和定时任务（CronJob）
一次性执行
应用场景：离线数据处理，视频解码等业务
job示例
[root@k8s-master1 ~]# vim job.yaml
apiVersion: batch/v1
kind: Job
metadata:
name: pi
spec:
template:
spec:
containers:
- name: pi
image: perl
command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
restartPolicy: Never
backoffLimit: 4
[root@k8s-master1 ~]# kubectl apply -f job.yaml
job.batch/pi created
[root@k8s-master1 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nfs-client-provisioner-f69cd5cf-rfbdb 1/1 Running 0 87m
pi-nslj8 0/1 Completed 0 119s
web-0 1/1 Running 0 71m
web-1 1/1 Running 0 72m
[root@k8s-master1 ~]# kubectl logs pi-nslj8
3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275898cronjob
https://kubernetes.io/docs/tasks/job/automated-tasks-with-cron-jobs/
定时任务，像Linux的Crontab一样。
应用场景：通知，备份
cronjob示例
[root@k8s-master1 ~]# vim cronjob.yaml
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: hello
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: hello
image: busybox
args:
- /bin/sh
- -c
- date; echo Hello from the Kubernetes cluster
restartPolicy: OnFailure
[root@k8s-master1 ~]# kubectl apply -f cronjob.yaml
cronjob.batch/hello created
[root@k8s-master1 ~]# kubectl get cronjob
NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE
hello */1 * * * * False 1 5s 8s
[root@k8s-master1 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
hello-1545968100-zhf2w 0/1 Completed 0 67s
hello-1545968160-zftxj 0/1 ContainerCreating 0 7s
nfs-client-provisioner-f69cd5cf-rfbdb 1/1 Running 0 96m
pi-nslj8 0/1 Completed 0 10m
web-0 1/1 Running 0 80m
web-1 1/1 Running 0 81m
[root@k8s-master1 ~]# kubectl logs hello-1545968100-zhf2w
Fri Dec 28 03:35:14 UTC 2018
Hello from the Kubernetes cluster
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