Kubernetes 之 StatefulSet
StatefulSet 定义
StatefulSet 是一个有状态的集合，不同于一般 Pod 的一致性，不同的 Stateful Set 创建的 Pod 之间存在数据上的差异。同时它们是有序的，这样它们在故障或删除后恢复，自身的名字也不会变化，以达到维护整个分布式系统的目的。例如在 Redis 主从集群中，我们不能用 Pod 模式来部署，以为主从容器之间的配置信息是不一样的，这时候我们就需要 Stateful Set 来实现我们的需求。
StatefulSet 的使用
apiVersion: v1
kind: Service
metadata:name: nginxlabels:app: nginx
spec:ports:- port: 80name: webclusterIP: Noneselector:app: pod-nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:name: stateful-set-web
spec:serviceName: "nginx"replicas: 2selector:matchLabels:app: pod-nginxtemplate:metadata:labels:app: pod-nginxspec:containers:- name: nginximage: registry.k8s.io/nginx-slim:0.8ports:- containerPort: 80name: webvolumeMounts:- name: wwwmountPath: /usr/share/nginx/htmlvolumeClaimTemplates:- metadata:name: wwwspec:storageClassName: nfs-clientaccessModes: [ "ReadWriteOnce" ]resources:requests:storage: 100Mi
---
kind: Pod
apiVersion: v1
metadata:name: stateful-set-test
spec:containers:- name: stateful-set-testimage: docker.io/k8s-test:v1.0restartPolicy: "Never"root@k8s-master1:~# kubectl get pods -owide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nfs-client-provisioner-d5bf6698d-mxjw2 1/1 Running 1 (61m ago) 23h 10.244.194.109 k8s-worker1 <none> <none>
stateful-set-test 1/1 Running 0 62s 10.244.126.56 k8s-worker2 <none> <none>
stateful-set-web-0 1/1 Running 0 62s 10.244.194.114 k8s-worker1 <none> <none>
stateful-set-web-1 1/1 Running 0 61s 10.244.126.57 k8s-worker2 <none> <none>root@k8s-master1:~# kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS VOLUMEATTRIBUTESCLASS AGE
www-stateful-set-web-0 Bound pvc-81e64b41-f60d-488f-8862-90c91f821641 100Mi RWO nfs-client <unset> 5m50s
www-stateful-set-web-1 Bound pvc-2d269bcd-297f-4bd9-9e5d-f24c41fc5c6b 100Mi RWO nfs-client <unset> 5m40sroot@k8s-master1:~# kubectl exec -it stateful-set-test -- /bin/sh
/ # curl nginx
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Nginx Test</title>
</head>
<body>
Hello Web1
</body>
</html>
/ # curl nginx
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Nginx Test</title>
</head>
<body>
Hello Web2
</body>
</html>