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: nginx
labels:
app: nginx
spec:
ports:
- port: 80
name: web
clusterIP: None
selector:
app: pod-nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: stateful-set-web
spec:
serviceName: "nginx"
replicas: 2
selector:
matchLabels:
app: pod-nginx
template:
metadata:
labels:
app: pod-nginx
spec:
containers:
- name: nginx
image: registry.k8s.io/nginx-slim:0.8
ports:
- containerPort: 80
name: web
volumeMounts:
- name: www
mountPath: /usr/share/nginx/html
volumeClaimTemplates:
- metadata:
name: www
spec:
storageClassName: nfs-client
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 100Mi
---
kind: Pod
apiVersion: v1
metadata:
name: stateful-set-test
spec:
containers:
- name: stateful-set-test
image: docker.io/k8s-test:v1.0
restartPolicy: "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> 5m40s
root@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>