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来实现有序收缩，有序删除（即从N-1到0）
1.（提前准备好nfs存储，之前有提过）
创建四个目录作为pv，分别对应于pv01、pv02、pv03、pv04
[root@master-01 statefulset]# ls /data/
pv-volume pv-volume2 pv-volume-test1 pv-volume-test2
2.创建pv
[root@master-01 statefulset]# cat pv.yaml
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv01
labels:
nfs-label: pv01
name: pv01
spec:
accessModes: ["ReadWriteMany"]
capacity:
storage: 2Gi
nfs:
server: 10.1.1.10
path: /data/pv-volume
storageClassName: local-storage
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv02
labels:
nfs-label: pv02
name: pv02
spec:
accessModes: ["ReadWriteMany"]
capacity:
storage: 2Gi
nfs:
server: 10.1.1.10
path: /data/pv-volume2
storageClassName: local-storage
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv03
labels:
nfs-label: pv03
name: pv03
spec:
accessModes: ["ReadWriteMany"]
capacity:
storage: 2Gi
nfs:
server: 10.1.1.10
path: /data/pv-volume-test1
storageClassName: local-storage
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv04
labels:
nfs-label: pv04
name: pv04
spec:
accessModes: ["ReadWriteMany"]
capacity:
storage: 2Gi
nfs:
server: 10.1.1.10
path: /data/pv-volume-test2
storageClassName: local-storage
[root@master-01 statefulset]# kubectl apply -f pv.yaml
persistentvolume/pv01 created
persistentvolume/pv02 created
persistentvolume/pv03 created
persistentvolume/pv04 created
[root@master-01 statefulset]# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pv01 2Gi RWX Retain Available local-storage 5s
pv02 2Gi RWX Retain Available local-storage 5s
pv03 2Gi RWX Retain Available local-storage 5s
pv04 2Gi RWX Retain Available local-storage 5s
3.创建statefulset绑定pv
[root@master-01 statefulset]# cat myapp-stateful.yaml
apiVersion: v1
kind: Service
metadata:
name: myapp
labels:
app: myapp
spec:
ports:
- port: 80
name: web
clusterIP: None
selector:
app: myapp
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: myapp-statefulset-test
namespace: default
spec:
replicas: 2
selector:
matchLabels:
app: myapp
release: canary
template:
metadata:
labels:
app: myapp
release: canary
spec:
imagePullSecrets:
- name: regsecret
containers:
- name: myapp
image: "harbor-ali.abc.com/k8s_img/myapp:v1"
imagePullPolicy: Always
ports:
- name: http
containerPort: 80
volumeMounts:
- name: myappdata
mountPath: /usr/share/nginx/html
serviceName: myapp
selector:
matchLabels:
app: myapp
volumeClaimTemplates:
- metadata:
name: myappdata
spec:
storageClassName: local-storage #存储卷名与pv的存储卷名对应
accessModes: ["ReadWriteMany"]
resources:
requests:
storage: 2Gi
[root@master-01 statefulset]# kubectl apply -f myapp-stateful.yaml
statefulset.apps/myapp-statefulset-test created
[root@master-01 statefulset]# kubectl get sts
NAME READY AGE
myapp-statefulset-test 2/2 11s
[root@master-01 statefulset]# kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
myappdata-myapp-statefulset-test-0 Bound pv04 2Gi RWX local-storage 27s
myappdata-myapp-statefulset-test-1 Bound pv01 2Gi RWX local-storage 23s
[root@master-01 statefulset]# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pv01 2Gi RWX Retain Bound default/myappdata-myapp-statefulset-test-1 local-storage 6m31s
pv02 2Gi RWX Retain Available local-storage 6m31s
pv03 2Gi RWX Retain Available local-storage 6m31s
pv04 2Gi RWX Retain Bound default/myappdata-myapp-statefulset-test-0 local-storage 6m31s
从结果可以看出statfulset会自动创建pvc并与相应的pod绑定
查看创建的Pod，他们都是有序的
[root@master-01 statefulset]# kubectl get pod
NAME READY STATUS RESTARTS AGE
myapp-statefulset-test-0 1/1 Running 0 3m17s
myapp-statefulset-test-1 1/1 Running 0 3m13s
可以pv的结果可以看到pv02/pv03是空闲未被绑定的
更新pod个数把副本数改为3，stateful会自动选择合适的pvc与之绑定
[root@master-01 statefulset]# kubectl patch statefulset myapp-statefulset-test -p '{"spec":{"replicas":3}}'
statefulset.apps/myapp-statefulset-test patched
[root@master-01 statefulset]# kubectl get pod
NAME READY STATUS RESTARTS AGE
myapp-statefulset-test-0 1/1 Running 0 6m23s
myapp-statefulset-test-1 1/1 Running 0 6m19s
myapp-statefulset-test-2 1/1 Running 0 92s
[root@master-01 statefulset]# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pv01 2Gi RWX Retain Bound default/myappdata-myapp-statefulset-test-1 local-storage 11m
pv02 2Gi RWX Retain Bound default/myappdata-myapp-statefulset-test-2 local-storage 11m
pv03 2Gi RWX Retain Available local-storage 11m
pv04 2Gi RWX Retain Bound default/myappdata-myapp-statefulset-test-0 local-storage 11m
pv02已绑定到新的pod