kubernetes核心概念 controller

kubernetes核心概念 Controller

一、pod控制器controller

1.1 Controller作用及分类

controller用于控制pod

参考: https://kubernetes.io/zh/docs/concepts/workloads/controllers/

控制器主要分为:

• 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

1.2 Deployment

1.2.1 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

1.2.2 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

1.2.3 Deployment用于部署无状态应用

无状态应用的特点:

• 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

1.2.4 创建deployment类型应用

1, 准备YAML文件

[root@k8s-master1 ~]# vim deployment-nginx.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: deploy-nginx			# deployment名
spec:				
  replicas: 1					# 副本集,deployment里使用了replicaset
  selector:
    matchLabels:
      app: nginx				# 匹配的pod标签,表示deployment和rs控制器控制带有此标签的pod
  template:					    # 代表pod的配置模板
    metadata:
      labels:
        app: nginx				# pod的标签
    spec:
      containers:				# 以下为pod里的容器定义
      - name: nginx
        image: nginx:1.15-alpine
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 80

2, 应用YAML文件创建deployment

[root@k8s-master1 ~]# kubectl apply -f deployment-nginx.yml
deployment.apps/deploy-nginx created

3, 查看验证

[root@k8s-master1 ~]# kubectl get deployment				# deployment可简写成depoly
NAME           READY   UP-TO-DATE   AVAILABLE   AGE
deploy-nginx   1/1     1            1           19s

[root@k8s-master1 ~]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
deploy-nginx-6c9764bb69-pbc2h   1/1     Running   0          75s

[root@k8s-master1 ~]# kubectl get replicasets				# replicasets可简写成rs
NAME                      DESIRED   CURRENT   READY   AGE
deploy-nginx-6c9764bb69   1         1         1       2m6s

1.2.5 访问deployment

1,查看pod的IP地址

[root@k8s-master1 ~]# kubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP               NODE          NOMINATED NODE   READINESS GATES
deploy-nginx-6d9d558bb6-88nr8   1/1     Running   0          39s   10.244.159.155   k8s-master1   <none>           <none>

pod在k8s-master1节点,pod的IP为10.244.159.155

2, 查看所有集群节点的网卡

[root@k8s-master1 ~]# ifconfig tunl0 |head -2
tunl0: flags=193<UP,RUNNING,NOARP>  mtu 1480
        inet 10.244.159.128  netmask 255.255.255.255

[root@k8s-master2 ~]# ifconfig tunl0 |head -2
tunl0: flags=193<UP,RUNNING,NOARP>  mtu 1480
        inet 10.244.224.0  netmask 255.255.255.255

[root@k8s-master3 ~]# ifconfig tunl0 |head -2
tunl0: flags=193<UP,RUNNING,NOARP>  mtu 1480
        inet 10.244.135.192  netmask 255.255.255.255

[root@k8s-worker1 ~]# ifconfig tunl0 |head -2
tunl0: flags=193<UP,RUNNING,NOARP>  mtu 1480
        inet 10.244.194.64  netmask 255.255.255.255

• 可以看到所有集群节点的IP都为10.244.0.0/16这个大网段内的子网

3, 在任意集群节点上都可以访问此deploy里pod

# curl 10.244.159.155

结果是任意集群节点都可以访问这个POD,但集群外部是不能访问的

1.2.6 删除deployment中的pod

1, 删除pod（注意: 是删除deployment中的pod）

[root@k8s-master1 ~]# kubectl delete pod deploy-nginx-6c9764bb69-pbc2h
pod "deploy-nginx-6c9764bb69-pbc2h" deleted

2, 再次查看,发现又重新启动了一个pod(节点由k8s-master1转为k8s-worker1 了,IP地址也变化了)

[root@k8s-master1 ~]# kubectl get pods  -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP              NODE          NOMINATED NODE   READINESS GATES
deploy-nginx-6d9d558bb6-f2t6r   1/1     Running   0          28s   10.244.194.94   k8s-worker1   <none>           <none>

也就是说**pod的IP不是固定的,比如把整个集群关闭再启动,pod也会自动启动,但是IP地址也会变化**

既然IP地址不是固定的,所以需要一个固定的访问endpoint给用户,那么这种方式就是service.

1.2.7 pod版本升级

查看帮助

[root@k8s-master1 ~]# kubectl set image -h

1, 升级前验证nginx版本

[root@k8s-master1 ~]# kubectl describe pods deploy-nginx-6d9d558bb6-f2t6r | grep Image:
    Image:          nginx:1.15-alpine
    
[root@k8s-master1 ~]# kubectl exec deploy-nginx-6d9d558bb6-f2t6r -- nginx -v
nginx version: nginx/1.15.12

2, 升级为1.16版

[root@k8s-master1 ~]# kubectl set image deployment deploy-nginx nginx=nginx:1.16-alpine --record
deployment.apps/deploy-nginx image updated

说明:

• deployment deploy-nginx代表名为deploy-nginx的deployment

• nginx=nginx:1.16-alpine前面的nginx为容器名

• –record 表示会记录

容器名怎么查看?

• kubectl describe pod pod名查看
• kubectl edit deployment deployment名来查看容器名
• kubectl get deployment deployment名 -o yaml来查看容器名

3, 验证

如果升级的pod数量较多，则需要一定时间，可通过下面命令查看是否已经成功

[root@k8s-master1 ~]# kubectl rollout status deployment deploy-nginx	
deployment "deploy-nginx" successfully rolled out

验证 pod

[root@k8s-master1 ~]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
deploy-nginx-5f4749c8c8-nskp9   1/1     Running   0          104s     更新后,后面的id变了

验证版本

[root@k8s-master1 ~]# kubectl describe pod deploy-nginx-5f4749c8c8-nskp9 |grep Image:
    Image:          nginx:1.16-alpine							升级为1.16了
    
[root@k8s-master1 ~]# kubectl exec deploy-nginx-5f4749c8c8-nskp9 -- nginx -v
nginx version: nginx/1.16.1										升级为1.16了

练习: 再将nginx1升级为1.17版

[root@k8s-master1 ~]# kubectl set image deployment deploy-nginx nginx=nginx:1.17-alpine --record
deployment.apps/deploy-nginx image updated

1.2.8 pod版本回退

1, 查看版本历史信息

[root@k8s-master1 ~]# kubectl rollout history deployment deploy-nginx
deployment.apps/deploy-nginx
REVISION  CHANGE-CAUSE
1         <none>												原1.15版
2         kubectl set image deployment deploy-nginx nginx=nginx:1.16-alpine --record=true
3         kubectl set image deployment deploy-nginx nginx=nginx:1.17-alpine --record=true

2, 定义要回退的版本（还需要执行才是真的回退版本)

[root@k8s-master1 ~]# kubectl rollout history deployment deploy-nginx --revision=1
deployment.apps/deploy-nginx with revision #1
Pod Template:
  Labels:       app=nginx
        pod-template-hash=6c9764bb69
  Containers:
   nginx:
    Image:      nginx:1.15-alpine				可以看到这是要回退的1.15版本
    Port:       80/TCP
    Host Port:  0/TCP
    Environment:        <none>
    Mounts:     <none>
  Volumes:      <none>

3, 执行回退

[root@k8s-master1 ~]# kubectl rollout undo deployment deploy-nginx --to-revision=1
deployment.apps/deploy-nginx rolled back

4, 验证

[root@k8s-master1 ~]# kubectl rollout history deployment deploy-nginx
deployment.apps/deploy-nginx
REVISION  CHANGE-CAUSE
2         kubectl set image deployment deploy-nginx nginx=nginx:1.16-alpine --record=true
3         kubectl set image deployment deploy-nginx nginx=nginx:1.17-alpine --record=true
4         <none>						回到了1.15版,但revision的ID变了

[root@k8s-master1 ~]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
deploy-nginx-6c9764bb69-zgwpj   1/1     Running   0          54s

[root@k8s-master1 ~]# kubectl describe pod deploy-nginx-6c9764bb69-zgwpj |grep Image:
    Image:          nginx:1.15-alpine				回到了1.15版

[root@k8s-master1 ~]# kubectl exec deploy-nginx-6c9764bb69-zgwpj -- nginx -v
nginx version: nginx/1.15.12						回到了1.15版

1.2.9 副本扩容

查看帮助

[root@k8s-master1 ~]# kubectl scale -h

1, 扩容为2个副本

[root@k8s-master1 ~]# kubectl scale deployment deploy-nginx --replicas=2
deployment.apps/deploy-nginx scaled

2, 查看

[root@k8s-master1 ~]# kubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP               NODE          NOMINATED NODE   READINESS GATES
deploy-nginx-6d9d558bb6-4c64l   1/1     Running   0          27s   10.244.159.157   k8s-master1   <none>           <none>
deploy-nginx-6d9d558bb6-hkq2b   1/1     Running   0          71s   10.244.194.95    k8s-worker1   <none>           <none>

在两个node节点上各1个pod

3, 继续扩容(我们这里只有2个node,但是可以大于node节点数据)

[root@master ~]# kubectl scale deployment deploy-nginx --replicas=4
deployment.extensions/nginx1 scaled

[root@k8s-master1 ~]# kubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE     IP               NODE          NOMINATED NODE   READINESS GATES
deploy-nginx-6d9d558bb6-4c64l   1/1     Running   0          87s     10.244.159.157   k8s-master1   <none>           <none>
deploy-nginx-6d9d558bb6-586dr   1/1     Running   0          31s     10.244.135.197   k8s-master3   <none>           <none>
deploy-nginx-6d9d558bb6-hkq2b   1/1     Running   0          2m11s   10.244.194.95    k8s-worker1   <none>           <none>
deploy-nginx-6d9d558bb6-kvgsc   1/1     Running   0          31s     10.244.224.13    k8s-master2   <none>           <none>

1.2.10 副本裁减

1, 指定副本数为1进行裁减

[root@k8s-master1 ~]# kubectl scale deployment deploy-nginx --replicas=1
deployment.apps/deploy-nginx scaled

2, 查看验证

[root@k8s-master1 ~]# kubectl get pods
NAME                            READY   STATUS    RESTARTS   AGE
deploy-nginx-6d9d558bb6-hkq2b   1/1     Running   0          2m56s

1.2.11 多副本滚动更新

1, 先扩容多点副本

[root@k8s-master1 ~]# kubectl scale deployment deploy-nginx --replicas=16
deployment.apps/deploy-nginx scaled

2, 验证

[root@master ~]# kubectl get pods
NAME                      READY   STATUS    RESTARTS   AGE
nginx1-7d9b8757cf-2hd48   1/1     Running   0          61s
nginx1-7d9b8757cf-5m72n   1/1     Running   0          61s
nginx1-7d9b8757cf-5w2xr   1/1     Running   0          61s
nginx1-7d9b8757cf-5wmdh   1/1     Running   0          61s
nginx1-7d9b8757cf-6szjj   1/1     Running   0          61s
nginx1-7d9b8757cf-9dgsw   1/1     Running   0          61s
nginx1-7d9b8757cf-dc7qj   1/1     Running   0          61s
nginx1-7d9b8757cf-l52pr   1/1     Running   0          61s
nginx1-7d9b8757cf-m7rt4   1/1     Running   0          26m
nginx1-7d9b8757cf-mdkj2   1/1     Running   0          61s
nginx1-7d9b8757cf-s79kp   1/1     Running   0          61s
nginx1-7d9b8757cf-shhvk   1/1     Running   0          61s
nginx1-7d9b8757cf-sv8gb   1/1     Running   0          61s
nginx1-7d9b8757cf-xbhf4   1/1     Running   0          61s
nginx1-7d9b8757cf-zgdgd   1/1     Running   0          61s
nginx1-7d9b8757cf-zzljl   1/1     Running   0          61s
nginx2-559567f789-8hstz   1/1     Running   1          114m

3, 滚动更新

[root@k8s-master1 ~]# kubectl set image deployment deploy-nginx nginx=nginx:1.17-alpine --record
deployment.apps/deploy-nginx image updated

4, 验证

[root@k8s-master1 ~]# kubectl rollout status deployment deploy-nginx
......
Waiting for deployment "deploy-nginx" rollout to finish: 13 of 16 updated replicas are available...
Waiting for deployment "deploy-nginx" rollout to finish: 14 of 16 updated replicas are available...
Waiting for deployment "deploy-nginx" rollout to finish: 15 of 16 updated replicas are available...
deployment "deploy-nginx" successfully rolled out

1.2.12 删除deployment

如果使用 kubectl delete deployment deploy-nginx 命令删除deployment,那么里面的pod也会被自动删除

1.3 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

2, 应用YAML文件

[root@k8s-master1 ~]# kubectl apply -f rs-nginx.yml
replicaset.apps/rs-nginx created

3, 验证

[root@k8s-master1 ~]# kubectl get rs
NAME       DESIRED   CURRENT   READY   AGE
rs-nginx   2         2         2       26s

[root@k8s-master1 ~]# kubectl get pods
NAME             READY   STATUS    RESTARTS   AGE
rs-nginx-7j9hz   1/1     Running   0          44s
rs-nginx-pncsk   1/1     Running   0          43s

[root@k8s-master1 ~]# kubectl get deployment
No resources found.

找不到deployment,说明创建rs并没有创建deployment

二、pod控制器Controller进阶

2.1 DaemonSet

2.1.1 DaemonSet介绍

• DaemonSet能够让所有（或者特定）的节点运行同一个pod。
• 当节点加入到K8S集群中，pod会被（DaemonSet）调度到该节点上运行，当节点从K8S集群中被移除，被DaemonSet调度的pod会被移除
• 如果删除DaemonSet，所有跟这个DaemonSet相关的pods都会被删除。
• 如果一个DaemonSet的Pod被杀死、停止、或者崩溃，那么DaemonSet将会重新创建一个新的副本在这台计算节点上。
• DaemonSet一般应用于日志收集、监控采集、分布式存储守护进程等

2.1.2 DaemonSet应用案例

1, 编写YAML文件

[root@master ~]# vim daemonset-nginx.yml
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: daemonset-nginx			
spec:
  selector:
    matchLabels:
      name: nginx-ds
  template:
    metadata:
      labels:
        name: nginx-ds
    spec:
      tolerations:						# tolerations代表容忍
      - key: node-role.kubernetes.io/master  # 能容忍的污点key
        effect: NoSchedule   # kubectl explain pod.spec.tolerations查看(能容忍的污点effect)
      containers:
      - name: nginx
        image: nginx:1.15-alpine
        imagePullPolicy: IfNotPresent
        resources:    # resources资源限制是为了防止master节点的资源被占太多(根据实际情况配置)
          limits:
            memory: 100Mi
          requests:
            memory: 100Mi

2, apply应用YAML文件

[root@k8s-master1 ~]# kubectl apply -f daemonset-nginx.yml
daemonset.apps/daemonset-nginx created

3, 验证文章来源地址https://www.toymoban.com/news/detail-503867.html

[root@master ~]# kubectl get daemonset				# daemonset可简写为ds
[root@k8s-master1 ~]# kubectl get ds
NAME              DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
daemonset-nginx   4         4         4       4            4           <none>          114s

[root@k8s-master1 ~]# kubectl get pods -o wide
NAME                    READY   STATUS    RESTARTS   AGE   IP               NODE          NOMINATED NODE   READINESS GATES
daemonset-nginx-94z6d   1/1     Running   0          6s    10.244.194.104   k8s-worker1   <none>           <none>
daemonset-nginx-hs9mk   1/1     Running   0          6s    10.244.135.206   k8s-master3   <none>           <none>
daemonset-nginx-jrcf5   1/1     Running   0          6s    10.244.159.167   k8s-master1   <none>           <none>
daemonset-nginx-sslpl   1/1     Running   0          6s    10.244.224.22    k8s-master2   <none>           <none>

k8s集群中每个节点都会运行一个pod

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