k8s (4)k8s控制器

末蓝、 2022-12-31 02:22 330阅读 0赞

### 文章目录 ###

*   *   *  控制器的介绍
         *   *  控制器类型
         *  ReplicaSet控制器
         *  Deployment控制器
         *  DaemonSet控制器
         *  job控制器
         *  cronjob

### 控制器的介绍 ###

#### 控制器类型 ####

*  1.Replication Controller和ReplicaSet  
    ReplicaSet 是下一代的 Replication Controller，官方推荐使用ReplicaSet。  
    ReplicaSet 和 Replication Controller 的唯一区别是选择器的支持，ReplicaSet 支持新的基于集合的选择器需求。ReplicaSet 确保任何时间都有指定数量的 Pod 副本在运行。虽然 ReplicaSets 可以独立使用，但今天它主要被Deployments 用作协调 Pod 创建、删除和更新的机制。
 *  2.Deployment  
    Deployment 为 Pod 和 ReplicaSet 提供了一个申明式的定义方法。典型的应用场景： 用来创建Pod和ReplicaSet 、滚动更新和回滚、扩容和缩容、暂停与恢复。
 *  3.DaemonSet  
    DaemonSet 确保全部（或者某些）节点上运行一个 Pod 的副本。当有节点加入集群时， 也会为他们新增一个 Pod 。当有节点从集群移除时，这些 Pod 也会被回收。删除 DaemonSet 将会删除它创建的所有 Pod。  
    DaemonSet 的典型用法：  
    • 在每个节点上运行集群存储 DaemonSet，例如 glusterd、ceph。  
    • 在每个节点上运行日志收集 DaemonSet，例如 fluentd、logstash。  
    • 在每个节点上运行监控 DaemonSet，例如 Prometheus Node Exporter、zabbix agent等  
    • 一个简单的用法是在所有的节点上都启动一个 DaemonSet，将被作为每种 类型的 daemon 使用。 • 一个稍微复杂的用法是单独对每种 daemon 类型使用多个 DaemonSet， 但具有不同的标志， 并且对不同硬件类型具有不同的内存、CPU 要求。
 *  4.StatefulSet  
    StatefulSet 是用来管理有状态应用的工作负载 API 对象。实例之间有不对 等关系，以及实例对外部数据有依赖关系的应用，称为“有状态应用”  
    StatefulSet 用来管理 Deployment 和扩展一组 Pod，并且能为这些 Pod 提供序号和唯一性保证。  
    StatefulSets 对于需要满足以下一个或多个需求的应用程序很有价值：  
    • 稳定的、唯一的网络标识符。  
    • 稳定的、持久的存储。  
    • 有序的、优雅的部署和缩放。  
    • 有序的、自动的滚动更新。
 *  5.Job  
    Job执行批处理任务，仅执行一次任务，保证任务的一个或多个Pod成功结束。
 *  6.CronJob  
    Cron Job 创建基于时间调度的 Jobs。 一个 CronJob 对象就像 crontab (cron table) 文件中的一行，它用 Cron 格式进行编写，并周期性地在给定的调度时间执行 Job。
 *  7.HPA  
    HPA根据资源利用率自动调整service中Pod数量，实现Pod水平自动缩放。

### ReplicaSet控制器 ###

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

控制器可以拉伸，收缩，但不能更新镜像  
如果将镜像副本数设置为6，则

Events:
      Type    Reason     Age   From               Message
      ----    ------     ----  ----               -------
      Normal  Scheduled  35s   default-scheduler  Successfully assigned default/replicaset-example-2jvcz to server2
      Normal  Pulling    30s   kubelet            Pulling image "myapp:v2"
      Normal  Pulled     29s   kubelet            Successfully pulled image "myapp:v2" in 917.754714ms
      Normal  Created    29s   kubelet            Created container myapp
      Normal  Started    28s   kubelet            Started container myapp

也就是说，新加的容器使用的是更新的镜像

### Deployment控制器 ###

[k8s@server1 ~]$ kubectl apply -f deployment.yml 
    deployment.apps/deployment-example created
    [k8s@server1 ~]$ cat deployment.yml 
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: deployment-example
    spec:
      replicas: 6
      selector:
        matchLabels:
          app: myapp
      template:
        metadata:
          labels:
            app: myapp
        spec:
          containers:
          - name: myapp
            image: myapp:v1
    [k8s@server1 ~]$ vim deployment.yml 
    [k8s@server1 ~]$ kubectl apply -f deployment.yml 
    deployment.apps/deployment-example configured

Events:
      Type    Reason     Age   From               Message
      ----    ------     ----  ----               -------
      Normal  Scheduled  89s   default-scheduler  Successfully assigned default/deployment-example-67f8c948cf-zxtbv to server3
      Normal  Pulled     86s   kubelet            Container image "myapp:v2" already present on machine
      Normal  Created    85s   kubelet            Created container myapp
      Normal  Started    84s   kubelet            Started container myap

deployment控制器是最常用的控制器

### DaemonSet控制器 ###

daemonset控制器可以每个节点部署一个容器

apiVersion: apps/v1
    kind: DaemonSet
    metadata:
      name: daemonset-example
      labels:
        k8s-app: zabbix-agent
    spec:
      selector:
        matchLabels:
          name: zabbix-agent
      template:
        metadata:
          labels:
            name: zabbix-agent
        spec:
          containers:
          - name: zabbix-agent
            image: zabbix-agent

[k8s@server1 ~]$ kubectl get pod -o wide
    NAME                                  READY   STATUS    RESTARTS   AGE   IP            NODE      NOMINATED NODE   READINESS GATES
    daemonset-example-7hsp8               1/1     Running   0          20s   10.244.1.44   server2   <none>           <none>
    daemonset-example-bg7l9               1/1     Running   0          20s   10.244.3.40   server3   <none>           <none>

### job控制器 ###

job控制器只执行一次

[k8s@server1 ~]$ cat job.yml 
    apiVersion: batch/v1
    kind: Job
    metadata:
      name: pi
    spec:
      template:
       metadata:
         name: pi
       spec:
         containers:
         - name: pi
           image: perl
           command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
         restartPolicy: Never

[k8s@server1 ~]$ kubectl get pod
    NAME       READY   STATUS      RESTARTS   AGE
    pi-7wt4t   0/1     Completed   0          8m2s
    [k8s@server1 ~]$ kubectl logs pi-7wt4t 
    3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275901

### cronjob ###

[k8s@server1 ~]$ cat cronjob.yml 
    apiVersion: batch/v1beta1 
    kind: CronJob 
    metadata:  
      name: cronjob-example 
    spec:  
      schedule: "* * * * *"  
      jobTemplate:    
        spec:      
          template:        
            spec:          
              containers:          
              - name: cronjob            
                image: busybox            
                args:            
                - /bin/sh            
                - -c            
                - date; echo Hello from k8s cluster          
              restartPolicy: OnFailure

每一分钟创建一个pod

[k8s@server1 ~]$ kubectl get pod
    NAME                               READY   STATUS      RESTARTS   AGE
    cronjob-example-1609081500-zwsdp   0/1     Completed   0          95s
    cronjob-example-1609081560-dsz8g   0/1     Completed   0          33s
    [k8s@server1 ~]$ kubectl logs cronjob-example-1609081500-zwsdp 
    Sun Dec 27 15:05:10 UTC 2020
    Hello from k8s cluster
    [k8s@server1 ~]$ kubectl logs cronjob-example-1609081560-dsz8g 
    Sun Dec 27 15:06:10 UTC 2020
    Hello from k8s cluster