Kubernetes基础：Deployment中ReplicaSet

╰+攻爆jí腚メ 2023-07-04 03:25 33阅读 0赞

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdW1pYW9jbg_size_16_color_FFFFFF_t_70_pic_center]  
Deployment是通过ReplicaSet来进行Pod的管理的，这篇文章通过一个简单的示例，对此进行说明。

# Deployment的YAML示例 #

有如下busybox的Deployment的YAML配置文件：

[root@host131 Deployment]# cat v1.yaml 
    ---
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: busybox-deployment-v1
    spec:
      replicas: 3
      selector:
        matchLabels:
          app: busybox-v1
      template:
        metadata:
          labels:
            app: busybox-v1
        spec:
          containers:
          - name: busybox-host
            image: busybox:1.31.1
            command: ["sleep"]
            args: ["1000"]
    ...
    [root@host131 Deployment]#

# 生成Deployment和Pod #

[root@host131 Deployment]# kubectl create -f v1.yaml 
    deployment.apps/busybox-deployment-v1 created
    [root@host131 Deployment]#

# 确认Deployment和Pod信息 #

[root@host131 Deployment]# kubectl get deployment -o wide
    NAME                    READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS     IMAGES           SELECTOR
    busybox-deployment-v1   3/3     3            3           9s    busybox-host   busybox:1.31.1   app=busybox-v1
    [root@host131 Deployment]# 
    [root@host131 Deployment]# kubectl get pods -o wide
    NAME                                     READY   STATUS    RESTARTS   AGE   IP             NODE              NOMINATED NODE   READINESS GATES
    busybox-deployment-v1-7bfdbd9656-9pg9s   1/1     Running   0          15s   10.254.152.6   192.168.163.131   <none>           <none>
    busybox-deployment-v1-7bfdbd9656-l4knv   1/1     Running   0          15s   10.254.152.7   192.168.163.131   <none>           <none>
    busybox-deployment-v1-7bfdbd9656-m8g9c   1/1     Running   0          15s   10.254.152.5   192.168.163.131   <none>           <none>
    [root@host131 Deployment]#

# 日志信息分析 #

## 确认Deployment ##

通过对Deployment和Pod等日志进行分析，确认在Deployment中生成Pod的顺序：

> 执行命令：kubectl describe deployment busybox-deployment-v1

主要日志信息：

Events:
      Type    Reason             Age   From                   Message
      ----    ------             ----  ----                   -------
      Normal  ScalingReplicaSet  34s   deployment-controller  Scaled up replica set busybox-deployment-v1-7bfdbd9656 to 3

可以看到出现了一个Replica Set，通过deployment-controller控制器创建，然后使用如下命令确认出了隐藏在后面工作的ReplicaSet, 此ReplicaSet的NAME与上述日志记载的名称相同

[root@host131 Deployment]# kubectl get rs -o wide
    NAME                               DESIRED   CURRENT   READY   AGE   CONTAINERS     IMAGES           SELECTOR
    busybox-deployment-v1-7bfdbd9656   3         3         3       54s   busybox-host   busybox:1.31.1   app=busybox-v1,pod-template-hash=7bfdbd9656
    [root@host131 Deployment]#

## 确认Replica Set ##

> 执行命令：kubectl describe rs busybox-deployment-v1-7bfdbd9656

主要日志信息：

Events:
      Type    Reason            Age   From                   Message
      ----    ------            ----  ----                   -------
      Normal  SuccessfulCreate  77s   replicaset-controller  Created pod: busybox-deployment-v1-7bfdbd9656-m8g9c
      Normal  SuccessfulCreate  77s   replicaset-controller  Created pod: busybox-deployment-v1-7bfdbd9656-9pg9s
      Normal  SuccessfulCreate  77s   replicaset-controller  Created pod: busybox-deployment-v1-7bfdbd9656-l4knv

可以清晰地看到3个Pod实例都是通过Replica Set生成的

## 确认Pod ##

> 执行命令：kubectl describe pod busybox-deployment-v1-7bfdbd9656-m8g9c

主要日志信息：

Events:
      Type    Reason     Age   From                      Message
      ----    ------     ----  ----                      -------
      Normal  Scheduled  94s   default-scheduler         Successfully assigned default/busybox-deployment-v1-7bfdbd9656-m8g9c to 192.168.163.131
      Normal  Pulled     92s   kubelet, 192.168.163.131  Container image "busybox:1.31.1" already present on machine
      Normal  Created    92s   kubelet, 192.168.163.131  Created container busybox-host
      Normal  Started    91s   kubelet, 192.168.163.131  Started container busybox-host

Pod的创建非常清晰：

*  由调度器决定在192.168.163.131这台节点上进行Pod的生成
 *  拉取镜像（镜像事前已经存在的情况）
 *  创建镜像 busybox-host
 *  启动镜像 busybox-host

# 总结 #

从上述示例可以清晰地看到Deployment生成Pode的过程：Deployment -> Replica Set -> Pod生成。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdW1pYW9jbg_size_16_color_FFFFFF_t_70_pic_center]: https://img-blog.csdnimg.cn/20200207173912376.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdW1pYW9jbg==,size_16,color_FFFFFF,t_70#pic_center