k8s核心概念Controller 基本操作和命令

controller主要用于控制pod

分类

• Deployments 部署无状态应用，控制pod升级,回退
• ReplicaSet 副本集,控制pod扩容,裁减
• ReplicationController(相当于ReplicaSet的老版本,现在建议使用Deployments加ReplicaSet替代RC)
• StatefulSets 部署有状态应用，结合Service、存储等实现对有状态应用部署
• DaemonSet 守护进程集，运行在所有集群节点(包括master), 比如使用filebeat,node_exporter
• Jobs 一次性
• Cronjob 周期性

Deployment控制器

Replicaset控制器的功能

• 支持新的基于集合的selector(以前的rc里没有这种功能)
• 通过改变Pod副本数量实现Pod的扩容和缩容

Deployment控制器的功能

• Deployment集成了上线部署、滚动升级、创建副本、回滚等功能
• Deployment里包含并使用了ReplicaSet

Deployment用于部署无状态应用及无状态服务特点

• 所有pod无差别
• 所有pod中容器运行同一个image
• 所有pod可以运行在集群中任意node上
• 所有pod无启动顺序先后之分
• 随意pod数量扩容或缩容
• 例如简单运行一个静态web程序

创建Deployment类型应用

准备yaml文件

• 可以先使用kubectl explain deployment查看相关的帮助

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-test
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 80
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应用YAML文件创建deployment

kubectl apply -f deployment_pod.yaml 
deployment.apps/deployment-test created
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验证

• 查看pod

kubectl get pod -o wide
NAME                               READY   STATUS    RESTARTS   AGE   IP           NODE             NOMINATED NODE   READINESS GATES
deployment-test-845d4d9dff-4kvmv   1/1     Running   0          85s   10.1.0.135   docker-desktop   <none>           <none>
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查看deployment

kubectl get deployment              
NAME              READY   UP-TO-DATE   AVAILABLE   AGE
deployment-test   1/1     1            1           29s
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删除deployment中的pod

直接删除pod

• 直接使用删除pod命令删除pod

kubectl delete pod deployment-test-845d4d9dff-4kvmv
pod "deployment-test-845d4d9dff-4kvmv" deleted
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• 查看pod

kubectl get pod -o wide                            
NAME                               READY   STATUS    RESTARTS   AGE   IP           NODE             NOMINATED NODE   READINESS GATES
deployment-test-845d4d9dff-xvvrq   1/1     Running   0          11s   10.1.0.136   docker-desktop   <none>           <none>
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• 发现直接删除pod，后台又重新调度起了一个pod，同时新起的IP也和老的不同

直接删除deployment

• 查看删除deployment

kubectl get deployment 
NAME              READY   UP-TO-DATE   AVAILABLE   AGE
deployment-test   1/1     1            1           5m39s

kubectl delete deployment deployment-test
deployment.apps "deployment-test" deleted
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• 查看deployment和pod

kubectl get deployment                   
No resources found in default namespace.

kubectl get pod                          
NAME                               READY   STATUS        RESTARTS   AGE
deployment-test-845d4d9dff-xvvrq   0/1     Terminating   0          3m18s
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pod版本改动

pod版本升级

• 查看pod当前版本:kubectl describe pod deployment-test-845d4d9dff-4cjd7
  
• 升级为1.16版本

kubectl set image deployment deployment-test nginx=nginx:1.16-alpine --record
deployment.apps/deployment-test image updated
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• 验证
  

pod版本回退

• 验证之前先讲pod的版本升级到nginx1.17

kubectl set image deployment deployment-test nginx=nginx:1.17-alpine --record
deployment.apps/deployment-test image updated
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• 查看版本历史信息

kubectl rollout history deployment deployment-test
deployment.apps/deployment-test
REVISION  CHANGE-CAUSE
1         <none>
2         kubectl set image deployment deployment-test nginx=nginx:1.16-alpine --record=true
3         kubectl set image deployment deployment-test nginx=nginx:1.17-alpine --record=true
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• 定义要回退的版本

zsx:~ zsx$ kubectl rollout undo deployment deployment-test --to-revision=1
deployment.apps/deployment-test rolled back
zsx:~ zsx$ kubectl rollout history deployment deployment-test
deployment.apps/deployment-test
REVISION  CHANGE-CAUSE
2         kubectl set image deployment deployment-test nginx=nginx:1.16-alpine --record=true
3         kubectl set image deployment deployment-test nginx=nginx:1.17-alpine --record=true
4         <none>
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副本数改动

• 因为nginx需要使用同一个端口，在此重新再给一个例子
• 编写yaml标签文件，在此已经准本好了相应的配置文件

apiVersion: apps/v1 
kind: Deployment  
metadata:   
  name: my-go-app1 
spec:     
  replicas: 1
  selector:
    matchLabels:
      app: go-app
  template: 
    metadata:
      labels:
        app: go-app
    spec: 
      containers:
        - name: go-app-container
          image: zsx123456/go-app-img
          ports:
            - containerPort: 3000
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• 查看启动pod

kubectl get pod
NAME                          READY   STATUS    RESTARTS   AGE
my-go-app1-7b77966865-fzxvn   1/1     Running   0          30s
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• 将副本扩展成2个

kubectl scale --replicas=2 -f deployment.yaml
deployment.apps/my-go-app1 scaled
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• 验证

kubectl get pod
NAME                          READY   STATUS    RESTARTS   AGE
my-go-app1-7b77966865-fzxvn   1/1     Running   0          2m25s
my-go-app1-7b77966865-nrjmd   1/1     Running   0          38s
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ReplicaSet

1, 编写YAML文件

[root@master ~]# vim rs-nginx.yml
apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: rs-nginx
  namespace: default
spec:                    # replicaset的spec
  replicas: 2            # 副本数
  selector:              # 标签选择器,对应pod的标签
    matchLabels:
      app: nginx         # 匹配的label
  template:
    metadata:
      name: nginx        # pod名
      labels:           # 对应上面定义的标签选择器selector里面的内容
        app: nginx
    spec:               # pod的spec
      containers:
      - name: nginx
        image: nginx:1.15-alpine
        ports:
        - name: http
          containerPort: 80
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2, 应用YAML文件

kubectl apply -f rs-nginx.yml
replicaset.apps/rs-nginx created
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3, 验证

kubectl get rs
NAME       DESIRED   CURRENT   READY   AGE
rs-nginx   2         2         2       26s
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kubectl get pods
NAME             READY   STATUS    RESTARTS   AGE
rs-nginx-7j9hz   1/1     Running   0          44s
rs-nginx-pncsk   1/1     Running   0          43s
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kubectl get deployment
No resources found.

找不到deployment,说明创建rs并没有创建deployment
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