deployment用于部署无状态应用

什么是无状态应用

1、所有pod无差别

2、所有pod中容器运行同一个镜像

3、所有pod可以运行在集群中任意node上

4、所有pod无启动顺序先后之分

5、随意pod数量扩容或缩容

创建一个deployment的控制器

查看deployment的apiversion信息

[root@master ~]# kubectl explain deployment
KIND:     Deployment
VERSION:  apps/v1
 

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-test   #deployment名字
  labels:
    app: deployment       #匹配的pod标签，表示deploymen控制器控制带有此标签的pod
spec:
  replicas: 2             #副本集，deploment里面使用了replicaset控制器
  selector:
    matchLabels:
      app: deployment       #匹配的pod标签，表示rs控制器控制带有此标签的pod
  template:
    metadata:
      labels:
        app: deployment      #pod的标签
    spec:
      containers:					# 以下为pod里的容器定义
      - name: nginx
        image: nginx:1.15-alpine
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 80

 kubectl apply -f nginx1-deployment.yml

[root@master k8s]# kubectl get deployments
NAME              READY   UP-TO-DATE   AVAILABLE   AGE
deployment-test   2/2     2            2           4m27s
可以看到这里创建了一个名字叫deployment-test的控制器，管理的pod数量是2个

[root@master k8s]# kubectl describe deployments deployment-test
Name:                   deployment-test
Namespace:              default                              #运行再default命名空间下
CreationTimestamp:      Fri, 19 Mar 2021 17:08:20 +0800
Labels:                 app=deployment         #控制该命名空间下标签为app=deployment的pod
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               app=deployment
Replicas:               2 desired | 2 updated | 2 total | 2 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=deployment
  Containers:
   nginx:
    Image:        nginx:1.15-alpine
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   deployment-test-59c79bc456 (2/2 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  6m37s  deployment-controller  Scaled up replica set deployment-test-59c79bc456 to 2

deployment的删除

被deployment控制的pod是没办法直接删除的，因为deployment控制会保证pod副本运行的数量，如果不够会自动启动一个新的pod，我们需要先删除控制器，那么里面的pod也会被自动删除

[root@master k8s]# kubectl delete deployments deployment-test
deployment.apps "deployment-test" deleted
[root@master k8s]# kubectl get pods
No resources found in default namespace.

pod版本升级

[root@master k8s]# kubectl describe pod deployment-test-59c79bc456-9vznb | grep Image:
    Image:          nginx:1.15-alpine
[root@master k8s]# kubectl set image deployment deployment-test nginx=nginx:1.16-alpine --record
deployment.apps/deployment-test image updated
[root@master k8s]# kubectl get pods
NAME                               READY   STATUS    RESTARTS   AGE
deployment-test-85f4f97dc5-g7szg   1/1     Running   0          24s
deployment-test-85f4f97dc5-vngqv   1/1     Running   0          21s
[root@master k8s]# kubectl describe pod deployment-test-85f4f97dc5-g7szg |grep Image:
    Image:          nginx:1.16-alpine

这里可以看到之前的版本是1.15 通过指定deployment升级成1.16版本

• deployment deployment-test代表名为deployment-test的deployment

• nginx=nginx:1.16-alpine前面的nginx为容器名

• --record 表示会记录