kubernetes(7)：rc副本控制器—滚动升级和一键回滚

rc副本控制器—滚动升级和一键回滚

http://www.bubuko.com/infodetail-2612308.html

https://www.cnblogs.com/luoahong/p/10300314.html

1 滚动升级

滚动升级是一种平滑的升级方式，通过逐步替换的策略，保证系统的文档。在初始升级的时候就可以及时发现、调整问题，以保证问题影响度不会被扩大。Kubernetes滚动升级命令：

kubectl rolling-update my-rcName-v1 -f my-rcName-v2-rc.yaml --update-period=10s

 

升级开始后，首先依据提供的定义文件创建V2版本的RC，然后每隔10s（--update-period=10s）逐步的增加V2版本的Pod副本数，逐步减少V1版本Pod的副本数。升级完成之后，删除V1版本的RC，保留V2版本的RC，及实现滚动升级。

升级过程中，发生了错误中途退出时，可以选择继续升级。Kubernetes能够智能的判断升级中断之前的状态，然后紧接着继续执行升级。当然，也可以进行回退，命令如下：

kubectl rolling-update my-rcName-v1 -f my-rcName-v2-rc.yaml --update-period=10s --rollback

 

2 新一代副本控制器ReplicaSet

replica set，可以被认为 是“升级版”的Replication Controller。replica set也是用于保证与label selector匹配的pod数量维持在期望状态。区别在于，replica set引入了对基于子集的selector查询条件，而Replication Controller仅支持基于值相等的selecto条件查询。replica set很少被单独使用，目前它多被Deployment用于进行pod的创建、更新与删除的编排机制。

2.1 RC（Replica Set）特性和作用

• 通过定义一个RC实现Pod的创建过程及副本数量的自动控制。
• RC 里包括完整的Pod定义模板。
• RC通过Label Selector 机制是对Pod副本的自动控制。
• 通过改变RC的副本数量，可以实现Pod副本的扩容和缩容。
• 通过改变RC里Pod模板中的镜像版本，可以实现Pod滚动升级。

3 Nginx滚动升级

3.1 查看当前容器运行nginx版本

[root@k8s-master ~]# kubectl get  pods -o wide        
NAME          READY     STATUS    RESTARTS   AGE       IP            NODE
myweb-q7cn1   1/1       Running   0          26m       172.16.14.2   k8s-node-2
myweb-xjrsn   1/1       Running   0          1h        172.16.73.3   k8s-node-1
test          1/1       Running   0          1h        172.16.73.2   k8s-node-1
[root@k8s-master ~]# kubectl describe rc myweb | grep Image
Image(s):       192.168.0.136:5000/nginx:latest
[root@k8s-master ~]#

 

3.2 下载其他版本并上传私有仓库

[root@k8s-master ~]# docker pull nginx:1.15
Trying to pull repository docker.io/library/nginx ... 
1.15: Pulling from docker.io/library/nginx
743f2d6c1f65: Pull complete 
6bfc4ec4420a: Pull complete 
688a776db95f: Pull complete 
Digest: sha256:23b4dcdf0d34d4a129755fc6f52e1c6e23bb34ea011b315d87e193033bcd1b68
[root@k8s-master ~]# docker images | grep nginx
192.168.0.136:5000/nginx                latest              5a3221f0137b        6 days ago          125.9 MB
docker.io/nginx                         latest              5a3221f0137b        6 days ago          125.9 MB
docker.io/nginx                         1.15                53f3fd8007f7        3 months ago        109.3 MB
[root@k8s-master ~]# docker tag docker.io/nginx:1.15 192.168.0.136:5000/nginx:1.15
[root@k8s-master ~]# docker push 192.168.0.136:5000/nginx:1.15
The push refers to a repository [192.168.0.136:5000/nginx]
332fa54c5886: Pushed 
6ba094226eea: Pushed 
6270adb5794c: Pushed 
1.15: digest: sha256:e770165fef9e36b990882a4083d8ccf5e29e469a8609bb6b2e3b47d9510e2c8d size: 948
[root@k8s-master ~]# docker images | grep nginx                                   
192.168.0.136:5000/nginx                latest              5a3221f0137b        6 days ago          125.9 MB
docker.io/nginx                         latest              5a3221f0137b        6 days ago          125.9 MB
192.168.0.136:5000/nginx                1.15                53f3fd8007f7        3 months ago        109.3 MB
docker.io/nginx                         1.15                53f3fd8007f7        3 months ago        109.3 MB
[root@k8s-master ~]# ls /opt/myregistry/docker/registry/v2/repositories/nginx/_manifests/tags/
1.15  latest
[root@k8s-master ~]#

 

3.3 删除所有pod和rc

[root@k8s-master ~]# kubectl get  pods
No resources found.
[root@k8s-master ~]# kubectl get rc
No resources found.
[root@k8s-master ~]#

 

3.4 创建一个旧版本的rc并启动

[root@k8s-master k8s]# cat myweb-rcv1.yaml
apiVersion: v1
kind: ReplicationController
metadata:
  name: myweb
spec:
  replicas: 3
  selector:
    app: myweb
  template:
    metadata:
      labels:
        app: myweb
    spec:
      containers:
      - name: myweb
        image: 192.168.0.136:5000/nginx:1.15
        ports:
        - containerPort: 80
[root@k8s-master k8s]#
[root@k8s-master k8s]# kubectl create  -f myweb-rcv1.yaml 
replicationcontroller "myweb" created
[root@k8s-master k8s]# kubectl get pods 
NAME          READY     STATUS    RESTARTS   AGE
myweb-94vm9   1/1       Running   0          4m
myweb-tgcvn   1/1       Running   0          4m
myweb-zjn61   1/1       Running   0          4m
[root@k8s-master k8s]#

 

3.5 创建升级rc

[root@k8s-master k8s]# cat myweb-rcv2.yaml  
apiVersion: v1
kind: ReplicationController
metadata:
  name: myweb2
spec:
  replicas: 3
  selector:
    app: myweb2
  template:
    metadata:
      labels:
        app: myweb2
    spec:
      containers:
      - name: myweb2
        image: 192.168.0.136:5000/nginx:latest
        ports:
        - containerPort: 80

 

3.6  执行升级

[root@k8s-master k8s]#  kubectl rolling-update myweb -f myweb-rcv2.yaml --update-period=20s
Created myweb2
Scaling up myweb2 from 0 to 3, scaling down myweb from 3 to 0 (keep 3 pods available, don't exceed 4 pods)
Scaling myweb2 up to 1
Scaling myweb down to 2
Scaling myweb2 up to 2
Scaling myweb down to 1
Scaling myweb2 up to 3
Scaling myweb down to 0
Update succeeded. Deleting myweb
replicationcontroller "myweb" rolling updated to "myweb2"
[root@k8s-master k8s]#

 

3.7 检查升级之后服务和镜像

[root@k8s-master k8s]# kubectl get pods  -o wide
NAME           READY     STATUS    RESTARTS   AGE       IP            NODE
myweb2-27ss0   1/1       Running   1          14m       172.16.47.3   k8s-node-2
myweb2-5xq3j   1/1       Running   1          15m       172.16.47.2   k8s-node-2
myweb2-s23qz   1/1       Running   1          15m       172.16.73.2   k8s-node-1
[root@k8s-master k8s]# curl -I 172.16.47.2 
HTTP/1.1 200 OK
Server: nginx/1.17.3
Date: Thu, 22 Aug 2019 05:44:46 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 13 Aug 2019 08:50:00 GMT
Connection: keep-alive
ETag: "5d5279b8-264"
Accept-Ranges: bytes

[root@k8s-master k8s]# kubectl describe pod myweb2-s23qz | grep -i image
    Image:                      192.168.0.136:5000/nginx:latest
    Image ID:                   docker-pullable://192.168.0.136:5000/nginx@sha256:099019968725f0fc12c4b69b289a347ae74cc56da0f0ef56e8eb8e0134fc7911
  16m           16m             1       {kubelet k8s-node-1}    spec.containers{myweb2} Normal          Pulling            pulling image "192.168.0.136:5000/nginx:latest"
  16m           16m             1       {kubelet k8s-node-1}    spec.containers{myweb2} Normal          Pulled             Successfully pulled image "192.168.0.136:5000/nginx:latest"
  2m            2m              1       {kubelet k8s-node-1}    spec.containers{myweb2} Normal          Pulling            pulling image "192.168.0.136:5000/nginx:latest"
  2m            2m              1       {kubelet k8s-node-1}    spec.containers{myweb2} Normal          Pulled             Successfully pulled image "192.168.0.136:5000/nginx:latest"

 

4 回滚

 

[root@k8s-master k8s]#  kubectl get pods -o wide
NAME           READY     STATUS    RESTARTS   AGE       IP            NODE
myweb2-27ss0   1/1       Running   1          19m       172.16.47.3   k8s-node-2
myweb2-5xq3j   1/1       Running   1          19m       172.16.47.2   k8s-node-2
myweb2-s23qz   1/1       Running   1          19m       172.16.73.2   k8s-node-1
[root@k8s-master k8s]# kubectl rolling-update myweb2 -f myweb-rcv1.yaml --update-period=10s
Created myweb
Scaling up myweb from 0 to 3, scaling down myweb2 from 3 to 0 (keep 3 pods available, don't exceed 4 pods)
Scaling myweb up to 1
Scaling myweb2 down to 2
Scaling myweb up to 2
Scaling myweb2 down to 1
Scaling myweb up to 3
Scaling myweb2 down to 0
Update succeeded. Deleting myweb2
replicationcontroller "myweb2" rolling updated to "myweb"
[root@k8s-master k8s]#  kubectl get rc 
NAME      DESIRED   CURRENT   READY     AGE
myweb     3         3         3         2m
[root@k8s-master k8s]#  kubectl get pods -o wide
NAME          READY     STATUS    RESTARTS   AGE       IP            NODE
myweb-b9231   1/1       Running   0          57s       172.16.47.2   k8s-node-2
myweb-csz1w   1/1       Running   0          45s       172.16.73.4   k8s-node-1
myweb-h3vtz   1/1       Running   0          2m        172.16.73.3   k8s-node-1
[root@k8s-master k8s]#

 

 

4.1 检查回滚之后服务和镜像

[root@k8s-master ~]# kubectl get rc                                     
NAME      DESIRED   CURRENT   READY     AGE
myweb     3         3         3         1h
[root@k8s-master ~]#
[root@k8s-master ~]# kubectl get pods -o wide
NAME          READY     STATUS    RESTARTS   AGE       IP            NODE
myweb-3gkq7   1/1       Running   0          1m        172.16.47.2   k8s-node-2
myweb-csz1w   1/1       Running   2          1h        172.16.73.2   k8s-node-1
myweb-h3vtz   1/1       Running   2          1h        172.16.73.3   k8s-node-1
[root@k8s-master ~]# 
[root@k8s-master ~]# curl -I 172.16.73.2 
HTTP/1.1 200 OK
Server: nginx/1.15.12
Date: Thu, 22 Aug 2019 07:28:10 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 16 Apr 2019 13:08:19 GMT
Connection: keep-alive
ETag: "5cb5d3c3-264"
Accept-Ranges: bytes

[root@k8s-master ~]# kubectl describe pod myweb-csz1w | grep -i image:
    Image:                      192.168.0.136:5000/nginx:1.15