Centos7 k8s Replication副本控制器

一、k8s副本控制器

　　Replication Controller (RC)是kubernetes 中的另一个核心概念，应用托管在kubernetes之后，kubernetes需要保证应用能够持续运行，这是RC的工作内容，它会确保任何时间kubernetes中都有指定数量的pod在运行。在此基础上，RC还提供了一些更高级的特性，比如滚动升级、升级回滚等。

　　1、创建配置文件

[root@k8s-master ~]# vim nginx-rc.yaml
apiVersion: v1
kind: ReplicationController
metadata:
name: nginx
spec:
replicas: 3
selector:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: 192.168.125.130:5000/nginx:1.19
ports:
- containerPort: 80

　　2、执行副本配置文件

[root@k8s-master ~]# kubectl create -f nginx-rc.yaml 
replicationcontroller "nginx" created

 replicationcontroller会再起三个pod，replicationcontroller会一直监控pod，一直保持3个，死一个，起一个，多一个，就自动杀死一个pod。

二、k8s lables标签管理

[root@k8s-master ~]# kubectl edit rc nginx                       手动修改pod配置文件
[root@k8s-master ~]# kubectl get all                             查看所有pod，带标签

 三、升级和降级

[root@k8s-master ~]# docker pull nginx:1.13                                                 拉取镜像
[root@k8s-master ~]# docker tag docker.io/nginx:1.13 192.168.125.130:5000/nginx:1.13        打标签
[root@k8s-master ~]# docker push  192.168.125.130:5000/nginx:1.13                           推送至私有仓库
[root@k8s-master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx 1/1 Running 0 1h
[root@k8s-master ~]# 
[root@k8s-master ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE
nginx 1/1 Running 0 1h 172.16.64.2 k8s-node2
[root@k8s-master ~]# curl -I 172.16.64.2
HTTP/1.1 200 OK
Server: nginx/1.19.0                                                                         查看版本为1.19版
Date: Wed, 10 Jun 2020 12:56:35 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 26 May 2020 15:00:20 GMT
Connection: keep-alive
ETag: "5ecd2f04-264"
Accept-Ranges: bytes

　　1、修改配置文件

[root@k8s-master ~]# cp nginx-rc.yaml nginx1.13-rc.yaml 
[root@k8s-master ~]# vim nginx1.13-rc.yaml
apiVersion: v1
kind: ReplicationController
metadata:
  name: nginx2
spec:
  replicas: 3
  selector:
     app: nginx2
  template:
     metadata:
       labels:
        app: nginx2
     spec:
       containers:
       - name: nginx2
         image: 192.168.125.130:5000/nginx:1.19                    镜像不能替换
         ports:
         - containerPort: 80
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:%s#nginx#nginx2#g                       把nginx批量替换成nginx2 
[root@k8s-master ~]# vimdiff nginx1.13-rc.yaml nginx.yaml

　　2、降级

[root@k8s-master ~]# kubectl rolling-update nginx -f nginx1.13-rc.yaml --update-period=10s                     降级间隔为10s
Created nginx2
Scaling up nginx2 from 0 to 3, scaling down nginx from 3 to 0 (keep 3 pods available, don't exceed 4 pods)
Scaling nginx2 up to 1
Scaling nginx down to 2
Scaling nginx2 up to 2
Scaling nginx down to 1
Scaling nginx2 up to 3
Scaling nginx down to 0
Update succeeded. Deleting nginx
replicationcontroller "nginx" rolling updated to "nginx2"
[root@k8s-master ~]# 

　　3、验证版本

[root@k8s-master ~]# kubectl get pod -o wide
NAME           READY     STATUS    RESTARTS   AGE       IP            NODE
nginx          1/1       Running   0          3h        172.16.64.2   k8s-node2
nginx2-516gh   1/1       Running   0          2m        172.16.74.4   k8s-node1
nginx2-p56cf   1/1       Running   0          2m        172.16.64.4   k8s-node2
nginx2-v6t11   1/1       Running   0          1m        172.16.74.2   k8s-node1
[root@k8s-master ~]# curl -I 172.16.64.4
HTTP/1.1 200 OK
Server: nginx/1.13.12                                                       版本为1.13版
Date: Wed, 10 Jun 2020 14:56:28 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Mon, 09 Apr 2018 16:01:09 GMT
Connection: keep-alive
ETag: "5acb8e45-264"
Accept-Ranges: bytes