StatefulSet
有状态应用副本集
无状态的, 更关注的是群体
有状态的, 更关注的是个体
有状态应用集的特点:
- 稳定且需要唯一的网络标识符;
- 稳定且持久的存储;
- 要求有序, 平滑的部署和扩展;
- 要求有序, 平滑的删除和终止;
- 有序的滚动更新;
需要有三个组件组成:
- headless service
- StatefulSet 控制器
- volumeClaimTemplate 存储卷申请模板
简单测试 使用 StatefulSet
创建基础的PV
[root@master configmap]# cat ../volume/pv-demo.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv001
labels:
name: pv001
spec:
nfs:
path: /data/volumes/v1
server: 10.0.20.20
accessModes: ["ReadWriteMany", "ReadWriteOnce"]
capacity:
storage: 5Gi
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv002
labels:
name: pv002
spec:
nfs:
path: /data/volumes/v2
server: 10.0.20.20
accessModes: ["ReadWriteOnce"]
capacity:
storage: 5Gi
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv003
labels:
name: pv003
spec:
nfs:
path: /data/volumes/v3
server: 10.0.20.20
accessModes: ["ReadWriteMany", "ReadWriteOnce"]
capacity:
storage: 5Gi
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv004
labels:
name: pv004
spec:
nfs:
path: /data/volumes/v4
server: 10.0.20.20
accessModes: ["ReadWriteMany", "ReadWriteOnce"]
capacity:
storage: 10Gi
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv005
labels:
name: pv005
spec:
nfs:
path: /data/volumes/v5
server: 10.0.20.20
accessModes: ["ReadWriteMany", "ReadWriteOnce"]
capacity:
storage: 10Gi
[root@master volume]# kubectl apply -f pv-demo.yaml
persistentvolume/pv001 created
persistentvolume/pv002 created
persistentvolume/pv003 created
persistentvolume/pv004 created
persistentvolume/pv005 created
[root@master volume]# kubectl get pv -o wide
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE VOLUMEMODE
pv001 5Gi RWO,RWX Retain Available 5s Filesystem
pv002 5Gi RWO Retain Available 5s Filesystem
pv003 5Gi RWO,RWX Retain Available 5s Filesystem
pv004 10Gi RWO,RWX Retain Available 5s Filesystem
pv005 10Gi RWO,RWX Retain Available 5s Filesystem
StatefulSet 清单
[root@master manifests]# cat statefulset-demo.yaml
apiVersion: v1
kind: Service
metadata:
name: myapp-svc
namespace: default
labels:
app: myapp # service 名称
spec:
ports:
- port: 80
name: web
clusterIP: None # 配置headless service
selector:
app: myapp-pod # 匹配Pod 标签
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: myapp
spec:
serviceName: myapp # 名称
replicas: 3 # 三个副本
selector:
matchLabels:
app: myapp-pod # 匹配Pod
template:
metadata:
labels:
app: myapp-pod
spec:
containers:
- name: myapp
image: ikubernetes/myapp:v1
ports:
- containerPort: 80
name: web
volumeMounts:
- name: myappdata
mountPath: /usr/shar/nginx/html
volumeClaimTemplates:
- metadata:
name: myappdata # pvc名称
spec:
accessModes: ["ReadWriteOnce"] # 权限
resources:
requests:
storage: 5Gi # pv 大小
创建
[root@master manifests]# kubectl apply -f statefulset-demo.yaml
service/myapp-svc unchanged
statefulset.apps/myapp created
[root@master manifests]# kubectl get sts
NAME READY AGE
myapp 3/3 5s
[root@master manifests]# kubectl get pods
NAME READY STATUS RESTARTS AGE
myapp-0 1/1 Running 0 92s
myapp-1 1/1 Running 0 91s
myapp-2 1/1 Running 0 32s
StatefulSet 会自动创建pvc, 然后去绑定对应符合要求的PV
[root@master manifests]# kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
myappdata-myapp-0 Bound pv002 5Gi RWO 2m42s
myappdata-myapp-1 Bound pv003 5Gi RWO,RWX 66s
myappdata-myapp-2 Bound pv001 5Gi RWO,RWX 7s
[root@master manifests]# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pv001 5Gi RWO,RWX Retain Bound default/myappdata-myapp-2 20m
pv002 5Gi RWO Retain Bound default/myappdata-myapp-0 20m
pv003 5Gi RWO,RWX Retain Bound default/myappdata-myapp-1 20m
pv004 10Gi RWO,RWX Retain Available 20m
pv005 10Gi RWO,RWX Retain Available 20m
最后, 声明式创建的, 可以使用 kubectl patch 命令 或者 kubectl set image 等命令对StatefulSet进行修改.