控制器

Pod 的分類:
- 自主式 Pod:Pod 退出後不會被創建
- 控制器管理的 Pod:在控制器的生命週期裏,始終要維持 Pod 的副本數目
控制器類型:
- Replication Controller和ReplicaSet
- Deployment
- DaemonSet
- StatefulSet
- Job //定時任務
- CronJob //重複任務
- HPA全稱Horizontal Pod Autoscaler

Replication Controller和ReplicaSet

ReplicaSet 是下一代的 Replication Controller,官方推薦使用ReplicaSet。
ReplicaSet 和 Replication Controller 的唯一區別是選擇器的支持,ReplicaSet支持新的基於集合的選擇器需求。
ReplicaSet 確保任何時間都有指定數量的 Pod 副本在運行。
雖然 ReplicaSets 可以獨立使用,但今天它主要被Deployments 用作協調 Pod 創
建、刪除和更新的機制。

Deployment

Deployment 爲 Pod 和 ReplicaSet 提供了一個申明式的定義方法。

典型的應用場景:

用來創建Pod和ReplicaSet
滾動更新和回滾
擴容和縮容
暫停與恢復

DaemonSet

DaemonSet 確保全部(或者某些)節點上運行一個 Pod 的副本。當有節點加入集羣時, 也會爲他們新增一個 Pod 。當有節點從集羣移除時,這些Pod 也會被回收。刪除 DaemonSet 將會刪除它創建的所有 Pod。

DaemonSet 的典型用法:

在每個節點上運行集羣存儲 DaemonSet,例如 glusterd、ceph。
在每個節點上運行日誌收集 DaemonSet,例如 fluentd、logstash。

在每個節點上運行監控 DaemonSet,例如 Prometheus Nodexporter、zabbix agent等
一個簡單的用法是在所有的節點上都啓動一個 DaemonSet,將被作爲每種
類型的 daemon 使用。
一個稍微複雜的用法是單獨對每種 daemon 類型使用多個 DaemonSet,
但具有不同的標誌, 並且對不同硬件類型具有不同的內存、CPU 要求。

StatefulSet

StatefulSet 是用來管理有狀態應用的工作負載 API 對象。實例之間有不對
等關係,以及實例對外部數據有依賴關係的應用,稱爲“有狀態應用”
StatefulSet 用來管理 Deployment 和擴展一組 Pod,並且能爲這些 Pod
提供序號和唯一性保證。
StatefulSets 對於需要滿足以下一個或多個需求的應用程序很有價值:
- 穩定的、唯一的網絡標識符。
- 穩定的、持久的存儲。
- 有序的、優雅的部署和縮放。
- 有序的、自動的滾動更新。

Job

執行批處理任務,僅執行一次任務,保證任務的一個或多個Pod成功結束。

CronJob

Cron Job 創建基於時間調度的 Jobs。
一個 CronJob 對象就像 crontab (cron table) 文件中的一行,它用 Cron
格式進行編寫,並週期性地在給定的調度時間執行 Job。

HPA

根據資源利用率自動調整service中Pod數量,實現Pod水平自動縮放。

Replicaset控制器示例

[root@server2 manifest]# vim rs.yml
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

[root@server2 manifest]# kubectl apply -f rs.yml 
replicaset.apps/replicaset-example created
[root@server2 manifest]# kubectl get pod -o wide
NAME                       READY   STATUS    RESTARTS   AGE   IP            NODE      NOMINATED NODE   READINESS GATES
replicaset-example-dcrwh   1/1     Running   0          16s   10.244.2.38   server4   <none>           <none>
replicaset-example-l8gw8   1/1     Running   0          16s   10.244.1.63   server3   <none>           <none>
replicaset-example-mlx8p   1/1     Running   0          16s   10.244.2.39   server4   <none>           <none>
[root@server2 manifest]# vim rs.yml
spec:
  replicas: 2		
[root@server2 manifest]# kubectl apply -f rs.yml 	直接應用，不用刪除之前的副本
replicaset.apps/replicaset-example configured
[root@server2 manifest]# kubectl get pod -o wide
NAME                       READY   STATUS        RESTARTS   AGE     IP            NODE      NOMINATED NODE   READINESS GATES
replicaset-example-dcrwh   1/1     Running       0          2m19s   10.244.2.38   server4   <none>           <none>
replicaset-example-l8gw8   1/1     Running       0          2m19s   10.244.1.63   server3   <none>           <none>
replicaset-example-mlx8p   0/1     Terminating   0          2m19s   10.244.2.39   server4   <none>           <none>
	//這個正在回收，默認會回收最新的pod
[root@server2 manifest]# kubectl  get all
NAME                           READY   STATUS    RESTARTS   AGE
pod/replicaset-example-dcrwh   1/1     Running   0          9m11s
pod/replicaset-example-l8gw8   1/1     Running   0          9m11s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   8d

NAME                                 DESIRED   CURRENT   READY   AGE
replicaset.apps/replicaset-example   2         2         2       9m11s
// 多了一個控制器在前面

那我們讓副本數不變，更換鏡像哪？

spec:
  replicas: 2
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:v2		// 改成v2

[root@server2 manifest]# kubectl  apply -f rs.yml 
replicaset.apps/replicaset-example configured
[root@server2 manifest]# kubectl get pod
NAME                       READY   STATUS    RESTARTS   AGE
replicaset-example-dcrwh   1/1     Running   0          11m
replicaset-example-l8gw8   1/1     Running   0          11m
// 還是這兩個pod，沒有變。

[root@server2 manifest]# vim  rs.yml
  replicas: 4		//再將副本改稱4個
...
        image: myapp:v2	
[root@server2 manifest]# kubectl  apply -f rs.yml 
replicaset.apps/replicaset-example configured
[root@server2 manifest]# kubectl get pod -o wide
NAME                       READY   STATUS    RESTARTS   AGE   IP            NODE      NOMINATED NODE   READINESS GATES
replicaset-example-bsckv   1/1     Running   0          2m    10.244.1.64   server3   <none>           <none>
replicaset-example-dcrwh   1/1     Running   0          15m   10.244.2.38   server4   <none>           <none>
replicaset-example-jkvfb   1/1     Running   0          2m    10.244.2.40   server4   <none>           <none>
replicaset-example-l8gw8   1/1     Running   0          15m   10.244.1.63   server3   <none>           <none>
// 新開起了兩個容器，我們進行訪問：

[root@server2 manifest]# curl 10.244.2.40
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
[root@server2 manifest]# curl 10.244.1.64
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
[root@server2 manifest]# curl 10.244.1.63
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
[root@server2 manifest]# curl 10.244.2.38
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>

//通過訪問我們發現，副本數不變更改鏡像，不會發生改變，增加副本數改變鏡像，新增的副本使用改變後的鏡像。

若要想直接全部更新，就需要使用deployment控制器了。

Deployment控制器

[root@server2 manifest]# vim deployment.yml
apiVersion: apps/v1
kind: Deployment	//和rs控制器寫法一致，只有這裏改變，因爲deployment調用的底層就是rs控制器
metadata:
  name: deployment-example
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:v1

[root@server2 manifest]# kubectl apply -f deployment.yml 
deployment.apps/deployment-example created
[root@server2 manifest]# kubectl get all
NAME                                      READY   STATUS    RESTARTS   AGE
pod/deployment-example-7449b5b68f-cnxsw   1/1     Running   0          18s
pod/deployment-example-7449b5b68f-kv7zb   1/1     Running   0          18s
pod/deployment-example-7449b5b68f-rfbtf   1/1     Running   0          18s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   8d

NAME                                 READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/deployment-example   3/3     3            3           18s

NAME                                            DESIRED   CURRENT   READY   AGE
replicaset.apps/deployment-example-7449b5b68f   3         3         3       18s

我們可以看到不止有deployment控制器，還有rs控制器。

pod/deployment-example-7449b5b68f-cnxsw
這個pod的名稱是由 pod 名 + rs名 + pod唯一標示 組成的.

[root@server2 manifest]# vim deployment.yml 
...
    spec:
      containers:
      - name: myapp
        image: myapp:v2		//將鏡像換爲v2
[root@server2 manifest]# kubectl apply -f deployment.yml 
kubec	deployment.apps/deployment-example configured

[root@server2 manifest]# kubectl get pod
NAME                                  READY   STATUS              RESTARTS   AGE
deployment-example-67764dd8bd-bqxt4   1/1     Running             0          7s
deployment-example-67764dd8bd-z8mf4   1/1     Running             0          5s
deployment-example-67764dd8bd-zwdgr   0/1     ContainerCreating   0          2s
deployment-example-7449b5b68f-cnxsw   0/1     Terminating         0          7m32s
deployment-example-7449b5b68f-kv7zb   1/1     Running             0          7m32s
deployment-example-7449b5b68f-rfbtf   1/1     Terminating         0          7m32s
[root@server2 manifest]# kubectl get pod
NAME                                  READY   STATUS        RESTARTS   AGE
deployment-example-67764dd8bd-bqxt4   1/1     Running       0          16s
deployment-example-67764dd8bd-z8mf4   1/1     Running       0          14s
deployment-example-67764dd8bd-zwdgr   1/1     Running       0          11s

現在我們在更換鏡像的時候會直接刪除原來的三個容器，重新打開三個pod。
而且：

[root@server2 manifest]# kubectl get all
...
NAME                                 READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/deployment-example   3/3     3            3           10m

NAME                                            DESIRED   CURRENT   READY   AGE
replicaset.apps/deployment-example-67764dd8bd   3         3         3       3m4s
replicaset.apps/deployment-example-7449b5b68f   0         0         0       10m

生成了一個新的rs控制器，但是原來的rs還保留着，這是用於回滾的。
新生成的三個pod都使用的是新的rs控制器生成的。

回滾

[root@server2 manifest]# vim deployment.yml 
...
    spec:
      containers:
      - name: myapp
        image: myapp:v1		//改回v1
[root@server2 manifest]# kubectl get pod
NAME                                  READY   STATUS    RESTARTS   AGE
deployment-example-7449b5b68f-c94st   1/1     Running   0          23s
deployment-example-7449b5b68f-f59mw   1/1     Running   0          20s
deployment-example-7449b5b68f-lwq2k   1/1     Running   0          17s
它就會使用原來的那個rs。

pod更新
當我們發現一個pod的狀態不正常時，我們可以直接刪除這個pod，控制器回自動的拉取一個新的pod：

[root@server2 manifest]# kubectl delete pod deployment-example-7449b5b68f-c94st 
pod "deployment-example-7449b5b68f-c94st" deleted
[root@server2 manifest]# kubectl get pod
NAME                                  READY   STATUS    RESTARTS   AGE
deployment-example-7449b5b68f-f59mw   1/1     Running   0          4m14s	//新pod
deployment-example-7449b5b68f-lwq2k   1/1     Running   0          4m11s
deployment-example-7449b5b68f-wwpgp   1/1     Running   0          17s

pod刪除

[root@server2 manifest]# kubectl delete  -f  deployment.yml 
deployment.apps "deployment-example" deleted
[root@server2 manifest]# kubectl get all
NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   8d
// 連同控制器，rs，pod一塊刪除了

多個控制器

多個控制器和多個資源的放時一樣，用—分割開就行了

[root@server2 manifest]# vim deployment.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-v1
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:v1

---		//分割線

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-v2
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:v2

[root@server2 manifest]# kubectl apply -f deployment.yml 
deployment.apps/deployment-v1 created
deployment.apps/deployment-v2 created
[root@server2 manifest]# kubectl get deployments.apps 
NAME            READY   UP-TO-DATE   AVAILABLE   AGE
deployment-v1   3/3     3            3           10s
deployment-v2   3/3     3            3           10s
[root@server2 manifest]# kubectl get rs
NAME                       DESIRED   CURRENT   READY   AGE
deployment-v1-7449b5b68f   3         3         3       105s
deployment-v2-67764dd8bd   3         3         3       105s
[root@server2 manifest]# kubectl get pod -o wide
NAME                             READY   STATUS    RESTARTS   AGE    IP            NODE      NOMINATED NODE   READINESS GATES
deployment-v1-7449b5b68f-csldb   1/1     Running   0          119s   10.244.1.73   server3   <none>           <none>
deployment-v1-7449b5b68f-srkxx   1/1     Running   0          119s   10.244.2.49   server4   <none>           <none>
deployment-v1-7449b5b68f-x5c59   1/1     Running   0          119s   10.244.2.50   server4   <none>           <none>
deployment-v2-67764dd8bd-bmmrc   1/1     Running   0          119s   10.244.2.51   server4   <none>           <none>
deployment-v2-67764dd8bd-m5c2g   1/1     Running   0          119s   10.244.1.75   server3   <none>           <none>
deployment-v2-67764dd8bd-zf8wx   1/1     Running   0          119s   10.244.1.74   server3   <none>           <none>

刪除

[root@server2 manifest]# kubectl delete deployments.apps deployment-v1
deployment.apps "deployment-v1" deleted
[root@server2 manifest]# kubectl get all
NAME                                 READY   STATUS        RESTARTS   AGE
pod/deployment-v1-7449b5b68f-g2s28   1/1     Terminating   0          87s
pod/deployment-v1-7449b5b68f-l4z8q   0/1     Terminating   0          87s
pod/deployment-v1-7449b5b68f-mqkqc   1/1     Terminating   0          87s
pod/deployment-v2-67764dd8bd-89t2z   1/1     Running       0          87s
pod/deployment-v2-67764dd8bd-rqsjn   1/1     Running       0          87s
pod/deployment-v2-67764dd8bd-sqrzg   1/1     Running       0          87s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   8d

NAME                            READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/deployment-v2   3/3     3            3           87s

NAME                                       DESIRED   CURRENT   READY   AGE
replicaset.apps/deployment-v2-67764dd8bd   3         3         3       87s

刪除v1，v2還在。

Daemonset控制器

Daemonset控制器適用於每個節點運行一個的pod。
我們之前使用的控制器不是在每個結點運行一個的，而是有可能都再一個結點運行：

[root@server2 manifest]# kubectl get pod -o wide
NAME                             READY   STATUS              RESTARTS   AGE   IP       NODE      NOMINATED NODE   READINESS GATES
deployment-v1-7449b5b68f-jz5h9   0/1     ContainerCreating   0          3s    <none>   server4   <none>           <none>
deployment-v1-7449b5b68f-lmksm   0/1     ContainerCreating   0          3s    <none>   server4   <none>           <none>
deployment-v1-7449b5b68f-v9d64   0/1     ContainerCreating   0          3s    <none>   server4   <none>           <none>

[root@server2 manifest]# vim daemonset.yml
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

[root@server2 manifest]# kubectl apply -f daemonset.yml 
daemonset.apps/daemonset-example created
[root@server2 manifest]# kubectl get pod -o wide
NAME                      READY   STATUS    RESTARTS   AGE   IP            NODE      NOMINATED NODE   READINESS GATES
daemonset-example-67tmd   1/1     Running   0          6s    10.244.1.78   server3   <none>           <none>
daemonset-example-qjtks   1/1     Running   0          6s    10.244.2.56   server4   <none>           <none>
//一個結點一個，新加入的結點頁回自動拉起一個這個pod

job控制器

[root@server2 manifest]# vim job.yml
apiVersion: batch/v1
kind: Job
metadata:
  name: example-job
spec:
  template:
    metadata:
      name: example-job
    spec:
      containers:
      - name: pi
        image: perl
        command: ["perl"]
        args: ["-Mbignum=bpi", "-wle", "print bpi(2000)"]	//計算pi的值.2000位
      restartPolicy: Never

[root@server2 manifest]# kubectl apply -f job.yml 
job.batch/example-job created
[root@server2 manifest]# kubectl get pod -w
NAME                READY   STATUS              RESTARTS   AGE
example-job-9vzb9   0/1     ContainerCreating   0          42s	//正在拉取鏡像，比較大
example-job-9vzb9   1/1     Running             0          50s	//正在計算
example-job-9vzb9   0/1     Completed           0          54s	//計算完畢
[root@server2 manifest]# kubectl logs example-job-9vzb9 
3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384
[root@server2 manifest]# kubectl get job
NAME          COMPLETIONS   DURATION   AGE
example-job   1/1           54s        3m16s
[root@server2 manifest]# kubectl delete -f job.yml 
job.batch "example-job" deleted
[root@server2 manifest]# kubectl get job
No resources found in default namespace.

cronjob控制器

執行週期性任務。

[root@server2 manifest]# vim cronjob.yml
apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: cronjob-example
spec:
  schedule: "* * * * *"		//每分鐘
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: cronjob
            image: busybox
            args:
            - /bin/sh
            - -c
            - date; echo Hello from k8s cluster
          restartPolicy: OnFailure
[root@server2 manifest]# kubectl apply -f cronjob.yml 
cronjob.batch/cronjob-example created
No resources found in default namespace.
[root@server2 manifest]# kubectl get pod 	//每分鐘執行一次，所以等待一分鐘
No resources found in default namespace.
[root@server2 manifest]# kubectl get pod 
NAME                               READY   STATUS      RESTARTS   AGE
cronjob-example-1593239100-hd4mk   0/1     Completed   0          3s
[root@server2 manifest]# kubectl logs cronjob-example-1593239100-hd4mk 
Sat Jun 27 06:25:03 UTC 2020
Hello from k8s cluster
//再等待一分鐘
[root@server2 manifest]# kubectl get pod 
NAME                               READY   STATUS      RESTARTS   AGE
cronjob-example-1593239100-hd4mk   0/1     Completed   0          60s
[root@server2 manifest]# kubectl get pod 
NAME                               READY   STATUS      RESTARTS   AGE
cronjob-example-1593239100-hd4mk   0/1     Completed   0          66s
cronjob-example-1593239160-mzwrz   0/1     Completed   0          5s	//又拉起一個

Kubernetes進階 -- 五種控制器的使用方法

控制器

Replicaset控制器示例

Deployment控制器

多個控制器

Daemonset控制器

job控制器

cronjob控制器

Kafka存儲機制

HTTP URL 詳解

kubernetes -- 結點調度控制的幾種方式

kubernetes存儲 -- Volumes管理（三）StatefulSet控制器、StatefulSet部署mysql主從集羣

kubernetes存儲 -- Volumes管理（一）emptyDir卷、hostpath卷、NFS卷

kubernetes存儲 -- Volumes管理（二）pv持久卷 +NFS、存儲類。

kubernetes存儲 -- Secret配置管理

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