K8S之pod控制器Deployment入门

• 说明
  kubernetes1.18及以后 都不支持命令行创建Deployment 建议大家采用配置配置文件的方式创建

在kubernetes中，Pod是最小的控制单元，但是kubernetes很少直接控制Pod，一般都是通过Pod控制器来完成的。Pod控制器用于pod的管理，确保pod资源符合预期的状态，当pod的资源出现故障时，会尝试进行重启或重建pod。

• 命令操作 1.18之前的版本可以 1.18之后的会报错

# 命令格式: kubectl create deployment 名称  [参数] 
# --image  指定pod的镜像
# --port   指定端口
# --replicas  指定创建pod数量
# --namespace  指定namespace
[root@master ~]# kubectl create deploy nginx --image=nginx:latest --port=80 --replicas=3 -n dev
deployment.apps/nginx created

# 查看创建的Pod
[root@master ~]# kubectl get pods -n dev
NAME                     READY   STATUS    RESTARTS   AGE
nginx-5ff7956ff6-6k8cb   1/1     Running   0          19s
nginx-5ff7956ff6-jxfjt   1/1     Running   0          19s
nginx-5ff7956ff6-v6jqw   1/1     Running   0          19s

# 查看deployment的信息
[root@master ~]# kubectl get deploy -n dev
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
nginx   3/3     3            3           2m42s

# UP-TO-DATE：成功升级的副本数量
# AVAILABLE：可用副本的数量
[root@master ~]# kubectl get deploy -n dev -o wide
NAME    READY UP-TO-DATE  AVAILABLE   AGE     CONTAINERS   IMAGES              SELECTOR
nginx   3/3     3         3           2m51s   nginx        nginx:latest        run=nginx

# 查看deployment的详细信息
[root@master ~]# kubectl describe deploy nginx -n dev
Name:                   nginx
Namespace:              dev
CreationTimestamp:      Wed, 08 May 2021 11:14:14 +0800
Labels:                 run=nginx
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               run=nginx
Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  run=nginx
  Containers:
   nginx:
    Image:        nginx:latest
    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:   nginx-5ff7956ff6 (3/3 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  5m43s  deployment-controller  Scaled up replicaset nginx-5ff7956ff6 to 3
  
# 删除 
[root@master ~]# kubectl delete deploy nginx -n dev
deployment.apps "nginx" deleted

• 配置文件

  一条yaml中有很多字段，如果去背这些字段，其实也能背过，但是去写一条yaml,也往往浪费很多的时间，也会出错，其实我们可以用一条命令就能快速来写一段自定义的yaml，工作中去修改相应的yaml也得心应手，效率也会很高，接下来我们来看一下

[root@master ~]# kubectl create deployment nginx --image=nginx -o yaml --dry-run > my-deployment.yaml
# -o yaml指定我们的yaml文件
# --dry-run 不在k8s中执行
# >重定向到我们的文件中

[root@k8s-master ~]# vim my-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
 creationTimestamp: null
 labels:
  app: nginx
 name: nginx
spec:
 replicas: 1
 selector:
  matchLabels:
   app: nginx
 strategy: {}
 template:
  metadata:
   creationTimestamp: null
   labels:
    app: nginx
  spec:
   containers:
   \- image: nginx
    name: nginx
    resources: {}
status: {}

• 这是新创建一条yaml文件，我们也可以根据我们的原有的pod来生成yaml，或者修改

[root@master ~]# kubectl get deploy nginx -o yaml --export > my-deploy2.yaml

-o yaml:指定yaml文件

--export:输出

[root@master ~]# cat my-deploy2.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "1"
  creationTimestamp: null
  generation: 1
  labels:
    run: nginx
  name: nginx
  selfLink: /apis/extensions/v1beta1/namespaces/default/deployments/nginx
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      run: nginx
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        run: nginx
    spec:
      containers:
      - image: nginx
        imagePullPolicy: Always
        name: nginx
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
status: {}

用代码改变命运，加油，努力，陌生人！