Kubernetes基本概念的学习-Deployment

一、Deployment控制器

Deployment是最常用的K8s负载控制器（Workload Controllers），是K8s的一个抽象概念，用于更高层级对象，部署和管理Pod。

Deployment的主要功能：

          管理Pod、即应用程序；

          具有上线部署、副本设定、滚动升级、回滚等功能

 

用于部署无状态的服务，这个最常用的控制器。一般用于管理维护企业内部无状态的微服务。比如confingserver、zuul、springboot。他可以管理多个副本的Pod，实现无缝的迁移，自动扩容、缩容、自动灾难恢复。

用命令创建一个Deployment：

[root@master01 ~]# kubectl create deployment nginx --image=nginx:1.15.2
deployment.apps/nginx created

导出这个deployment对应的yaml文件

[root@master01 ~]# kubectl get deployment -o yaml > nginx-deploy.yaml

 

1.1、验证滚动升级 ,实现零停机发布，用户无感知 

创建新的pod及service

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.16

---
apiVersion: v1
kind: Service
metadata:
   name: web
spec: 
  selector:
     app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: NodePort

查看创建的pod及service

[root@master01 ~]# kubectl get pod,service
NAME                       READY   STATUS    RESTARTS   AGE
pod/web-6d4cf56db6-jclts   1/1     Running   0          45s
pod/web-6d4cf56db6-strfs   1/1     Running   0          45s
pod/web-6d4cf56db6-xtrrs   1/1     Running   0          45s

NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
service/kubernetes   ClusterIP   10.1.0.1       <none>        443/TCP        7d2h
service/web          NodePort    10.1.129.126   <none>        80:31151/TCP   45s

 修改yaml中nginx的版本

    spec:
      containers:
      - name: nginx
        image: nginx:1.17

重新执行yaml

[root@master01 ~]# kubectl apply -f dema.yaml 
deployment.apps/web configured
service/web unchanged

观察pod滚动升级

[root@master01 ~]# kubectl get pod
NAME                   READY   STATUS              RESTARTS   AGE
web-6d4cf56db6-jclts   1/1     Running             0          41m
web-6d4cf56db6-strfs   1/1     Running             0          41m
web-6d4cf56db6-xtrrs   1/1     Running             0          41m
web-db749865c-dg2dh    0/1     ContainerCreating   0          5s
[root@master01 ~]# kubectl get pod
NAME                   READY   STATUS              RESTARTS   AGE
web-6d4cf56db6-jclts   1/1     Running             0          41m
web-6d4cf56db6-strfs   1/1     Running             0          41m
web-6d4cf56db6-xtrrs   1/1     Running             0          41m
web-db749865c-dg2dh    0/1     ContainerCreating   0          14s
[root@master01 ~]# kubectl get pod
NAME                   READY   STATUS              RESTARTS   AGE
web-6d4cf56db6-strfs   0/1     Terminating         0          42m
web-6d4cf56db6-xtrrs   1/1     Running             0          42m
web-db749865c-dg2dh    1/1     Running             0          54s
web-db749865c-k5m5t    0/1     ContainerCreating   0          3s
web-db749865c-q2wlt    1/1     Running             0          21s
[root@master01 ~]# kubectl get pod
NAME                  READY   STATUS    RESTARTS   AGE
web-db749865c-dg2dh   1/1     Running   0          60s
web-db749865c-k5m5t   1/1     Running   0          9s
web-db749865c-q2wlt   1/1     Running   0          27s

 用参数describe查看升级信息

[root@master01 ~]# kubectl describe deployment web

另外一种方法使用kubectl

[root@master01 ~]# kubectl set image deployment web nginx=nginx:1.18
deployment.apps/web image updated

1.2  应用发布失败回滚

查看之前升级过的版本， CHANGE-CAUSE，可以在升级版本的时候将参数--record=true 

[root@master01 ~]# kubectl rollout history deployment web
deployment.apps/web 
REVISION  CHANGE-CAUSE
1         <none>
3         <none>
4         <none>

使用rollout  undo命令回滚

[root@master01 ~]# kubectl rollout undo deployment web
deployment.apps/web rolled back

 回滚到指定的版本：

[root@master01 ~]# kubectl rollout undo deployment web --to-revision=5
deployment.apps/web rolled back

 

1.3  扩容和缩容

修改yaml文件的replicas，改为想要的副本数目；

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
spec:
  replicas: 3

然后重新apply

[root@master01 ~]# kubectl apply -f dema.yaml 
deployment.apps/web configured
service/web unchanged

查看结果

[root@master01 ~]# kubectl get pod -w
NAME                  READY   STATUS    RESTARTS   AGE
web-db749865c-48jds   1/1     Running   1          14h
web-db749865c-c279p   1/1     Running   1          14h
web-db749865c-gdszd   1/1     Running   1          14h
web-db749865c-mh2ml   1/1     Running   0          3m5s

第二种方法是用户命令行

[root@master01 ~]# kubectl scale deployment web --replicas=2
deployment.apps/web scaled

1.4 Deployment更新的停止和启动

停止更新，执行更新命令后不会立即生效，

[root@master01 ~]# kubectl rollout  pause deployment  web 

启动更新，前面执行的所有更新命令一次开始执行生效

[root@master01 ~]# kubectl rollout  pause deployment  web 

 

1.5应用下线

通过命令删除文件

[root@master01 ~]# kubectl delete -f dema.yaml 
deployment.apps "web" deleted
service "web" deleted

第二种方法是删除deployment

[root@master01 ~]# kubectl delete deployment web
deployment.apps "web" deleted