k8s笔记 | StatefulSet 有状态

创建一个web.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:
  serviceName: "nginx" # 使用那个service来管理dns
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:latest
          ports: # 容器暴露的端口
            - containerPort: 80 # 具体暴露的端口号
              name: web #该端口配置的名字
          # volumeMounts:
          #   - name: www #指定加载那个数据券
          #     mountPath: /usr/share/nginx/html #加载到容器中的那个目录

操作步骤如下：

# 创建
kubectl create sts -f web.yaml
# 查看
kubeclt get sts,svc,po
# 查看ip信息
kubectl run -it --image busybox:1.28.4 dns-test /bin/sh
nslookup web-0.nginx

#打印信息如下
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      web-0.nginx
Address 1: 10.244.107.210 web-0.nginx.default.svc.cluster.local

# 扩容，缩容 两种方式，选择其一
kubectl scale statefulset web --replicas=5
kubectl patch statefulset web -p '{"spec":{"replicas":2}}'

# 查看描述信息
kubectl descrbe sts web

...
Events:
  Type    Reason            Age    From                    Message
  ----    ------            ----   ----                    -------
  Normal  SuccessfulCreate  28m    statefulset-controller  create Pod web-0 in StatefulSet web successful
  Normal  SuccessfulCreate  27m    statefulset-controller  create Pod web-1 in StatefulSet web successful
  Normal  SuccessfulCreate  9m13s  statefulset-controller  create Pod web-2 in StatefulSet web successful
  Normal  SuccessfulCreate  8m52s  statefulset-controller  create Pod web-3 in StatefulSet web successful
  Normal  SuccessfulCreate  8m32s  statefulset-controller  create Pod web-4 in StatefulSet web successful
  Normal  SuccessfulDelete  6m28s  statefulset-controller  delete Pod web-4 in StatefulSet web successful
  Normal  SuccessfulDelete  6m25s  statefulset-controller  delete Pod web-3 in StatefulSet web successful
  Normal  SuccessfulDelete  6m23s  statefulset-controller  delete Pod web-2 in StatefulSet web successful

镜像更新

kubectl patch sts web --type='json' -p='[{"op":"replace","path":"/spec/template/spec/containers/0/image","value":"nginx:latest"}]'

# 这里有可能报错，那就把  "nginx:1.9.1" 改为 "nginx:1.26" 请注意到hub.docker.net去查看对应的版本

查看更新记录

# 查看所有
kubectl rollout history sts web

# 结果
statefulset.apps/web 
REVISION  CHANGE-CAUSE
1         <none>
2         <none>


# 指定查看对应的版本 
kubectl rollout history sts web --revision=2

# 结果
statefulset.apps/web with revision #2
Pod Template:
  Labels:       app=nginx
  Containers:
   nginx:
    Image:      nginx:1.9.1
    Port:       80/TCP
    Host Port:  0/TCP
    Environment:        <none>
    Mounts:     <none>
  Volumes:      <none>


# 查看状态
kubectl rollout status sts web

灰度发布

利用滚动更新中的partition 属性，可以实现简易的灰度发布效果

简介：加入我们有5个pod,如果当partition设置为3，那么此时滚动更新是，只会更新需要>=3的pod,利用该机制，我们可以通过控制partion来决定更新那一部分的内容，确定没有问题后，在逐渐增大更新pod的数量；如果partition为0 ，那表示所有的都更新

# 修改sts配置文件
kubectl edit sts web

# 修改partition:3  和 nignx:latest 
# 保存退出，通过kubectl describe po web-4  和 web-0 就能看到效果

StatefulSet的删除

# 练级删除 会删除sts和pod

kubectl delete sts web

# 非联级删除
kubectl delete sts web --cascade=false

# 删除services
kubectl delete svc nginx