kubernetes-控制器

一、replicaset

二、deployment

1、版本迭代

2、回滚

3、滚动更新策略

4、暂停与恢复

三、daemonset

四、statefulset

五、job

六、cronjob

一、replicaset

ReplicaSet用于保证指定数量的 Pod 副本一直运行

vim rs-example.yml

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: replicaset-example
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx

kubectl apply -f rs-example.yml
kubectl get pod --show-labels

replicaset是通过标签匹配pod

kubectl label pod replicaset-example-c7bs2 app=myapp --overwrite
kubectl get pod --show-labels

kubectl label pod replicaset-example-c7bs2 app=nginx --overwrite
kubectl get pod --show-labels

replicaset自动控制副本数量，pod可以自愈

kubectl delete pod replicaset-example-c7bs2
kubectl get pod --show-labels

回收资源

kubectl delete -f rs-example.yml

二、deployment

Deployment 的主要作用是实现应用程序的无缝升级和回滚

vim deployment-example.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-example
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:v1


kubectl apply -f deployment-example.yaml

1、版本迭代

replicaset就是deployment的一个版本

2、回滚

vim deployment-example.yaml 

kubectl apply -f deployment-example.yaml
kubectl get all

3、滚动更新策略

vim deployment-example.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-example
spec:
  minReadySeconds: 5
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:v1

kubectl apply -f deployment-example.yaml
kubectl describe deployments.apps deployment-example

4、暂停与恢复

暂停，避免触发不必要的线上更新

kubectl rollout pause deployment deployment-example

vim deployment-example.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-example
spec:
  minReadySeconds: 5
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  replicas: 6
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: nginx
        resources:
          limits:
            cpu: 0.5
            memory: 200Mi
          requests:
            cpu: 0.5
            memory: 200Mi

kubectl apply -f deployment-example.yaml

调整副本数，不受影响

但是更新镜像和修改资源并没有触发更新

kubectl rollout history deployment deployment-example

恢复后开始触发更新

kubectl rollout resume deployment deployment-example
kubectl rollout history  deployment deployment-example

回收

kubectl delete -f deployment-example.yaml

三、daemonset

Taints（污点）是一种标记，可以应用于节点，用于表示这个节点上的某些条件不适合运行某些 Pod。

vim daemonset-example.yml

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: daemonset-example
spec:
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      tolerations:
      - effect: NoSchedule
        operator: Exists
      containers:
      - name: nginx
        image: nginx

kubectl apply -f daemonset-example.yml
kubectl get pod -o wide

记得回收资源

四、statefulset

当使用StatefulSet时，Pod的名称会包括一个索引，例如web-0，web-1，web-2等，这些索引是按顺序递增的，并且在Pod的生命周期中保持不变

StatefulSet保证每个Pod的名称在整个集群中是唯一的，例如，如果您有一个名为web-0的Pod，任何时候都不能重新创建一个叫做web-0的Pod。

vim statefulset.yaml

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  selector:
    matchLabels:
      app: nginx
  serviceName: "nginx"
  replicas: 3
  minReadySeconds: 3
  template:
    metadata:
      labels:
        app: nginx
    spec:
      terminationGracePeriodSeconds: 10
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
          name: web

kubectl apply -f statefulset.yaml
kubectl get pod

五、job

Job是用于处理一次性任务的控制器，它可以保证任务成功完成后自动停止。Job中包含一个或多个Pods，在Pods成功完成后便完成任务。如果Pods失败，则Job会重启Pods，直到任务完成。

提前将perl上传至harbor仓库

vim job.yml


apiVersion: batch/v1
kind: Job
metadata:
  name: pi
spec:
  completions: 6        //完成任务的Pod数量
  parallelism: 2        //并行执行的Pod数量
  template:
    spec:
      containers:
      - name: pi
        image: perl:5.34.0
        command: ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
      restartPolicy: Never        //完成后不会重启
  backoffLimit: 4            //当任务执行失败时，最多重试的次数

kubectl apply -f job.yml

记得回收资源

六、cronjob

CronJob是用于处理周期性任务的控制器，它类似于传统的Cron定时任务，可以基于指定的时间或时间间隔来执行任务。CronJob会创建一个Job对象来运行任务，Job对象运行完成后自动被删除。如果Job对象出现错误，CronJob将会自动重启Job对象，直到任务成功完成。

vim cronjob.yml

apiVersion: batch/v1
kind: CronJob
metadata:
  name: hello
spec:
  schedule: "* * * * *"
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: hello
            image: busybox
            imagePullPolicy: IfNotPresent
            command:
            - /bin/sh
            - -c
            - date; echo Hello from the Kubernetes cluster
          restartPolicy: OnFailure

kubectl apply -f cronjob.yml
kubectl get all
kubectl get pod
kubectl delete -f cronjob.yml

每分钟的每一秒都会执行一次,使用busybox镜像来打印当前时间并输出"Hello from the Kubernetes cluster"