deployment(部署)

部署应用的对象，一个 Deployment 控制器为 Pods 和 ReplicaSets 提供声明式的更新能力，也就是应用的滚动更新和回滚。也可以进行设定数。

deployment是一个控制器，用于部署无状态应用。

控制器用于管理pod, 通过标签来管理pod.

下面是 Deployment 示例。负责启动3个 nginx Pods deployment.yaml文件内容为

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
        app: nginx
spec:
  replicas: 3
  selector:
        matchLabels:
          app: nginx
  template:
        metadata:
          labels:
                app: nginx
        spec:
          containers:
          - name: nginx
                image: nginx:1.14.2
                ports:
                - containerPort: 80

创建deployment

kubectl  apply -f deployment.yaml

查看deployments状态, 现在还没有Ready:

[root@zhang1 k8s]# kubectl get deployments
     NAME               READY   UP-TO-DATE   AVAILABLE   AGE
     nginx-deployment   0/3     3            0           27s

过了一段时间，查看deployments状态, 现在已经有两个Ready

[root@zhang1 k8s]# kubectl get deployments
     NAME               READY   UP-TO-DATE   AVAILABLE   AGE
     nginx-deployment   2/3     3            2           5m13s

在检查集群中的 Deployment 时，所显示的字段有：

NAME 列出了集群中 Deployment 的名称。
READY 显示应用程序的可用的副本数。显示的模式是“就绪个数/期望个数”。
UP-TO-DATE
AVAILABLE 显示应用可供用户使用的副本数。
AGE 显示应用程序运行的时间。

查看部署状态

$ kubectl rollout status deployment.v1.apps/nginx-deployment
deployment "nginx-deployment" successfully rolled out

使用describe获取 Deployment 的更多信息

[root@zhang1 ]# kubectl describe deployments nginx-deployment
Name:                   nginx-deployment
Namespace:              default
CreationTimestamp:      Mon, 09 Nov 2020 01:15:15 -0500
Labels:                 app=nginx
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               app=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:  app=nginx
  Containers:
   nginx:
        Image:        nginx:1.14.2
        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-deployment-66b6c48dd5 (3/3 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  34m   deployment-controller  Scaled up replica set nginx-deployment-66b6c48dd5 to 3

扩缩容

缩放 Deployment, 可以使用如下指令缩放 Deployment

$ kubectl scale deployment.v1.apps/nginx-deployment --replicas=2
deployment.apps/nginx-deployment scaled

更新(滚动升级)

会部署新的版本，待成功后再有序删除旧版本，命令如下

kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record

可以使用 kubectl get pod -o yaml来查看容器版本，看看是否升级ok。

涉及到以下几个命令

kubectl scale # 扩容
kubectl rollout status
kubectl rollout history #
kubectl rollout undo # 回到先前版本。

deployment(部署)

扩缩容

更新(滚动升级)

参考资料