[系统运维]kubernetes Deployment Pod集群

Deployment是一个kubernetes资源对象，用于创建Pod集群，前身是RC和RS，也是现在创建无状态服务的首选对象。

一个简单的Deployment示例：

# cat deploy.yaml 

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: deploy-myapp    # 标签需要一致
  name: deployment-demo
spec:
  replicas: 2
  selector:
    matchLabels:
      app: deploy-myapp    # 标签需要一致
  template:
    metadata:
      labels:
        app: deploy-myapp    # 标签需要一致
    spec:
      containers:
      - name: nginx-demo    # pod中的容器名称，docker ps 过滤该名称能看到
        image: nginx:1.20
        ports:
          - containerPort: 80

查看deployment

# kubectl get deployments.apps --show-labels -l app=deploy-myapp
NAME              READY   UP-TO-DATE   AVAILABLE   AGE   LABELS
deployment-demo   2/2     2            2           38m   app=deploy-myapp

查看deployment详情（启动有异常也通过该方法查看）

# kubectl describe deploy/deployment-demo

Name:                   deployment-demo
Namespace:              default
CreationTimestamp:      Wed, 16 Mar 2022 11:08:27 +0800
Labels:                 app=deploy-myapp
Annotations:            deployment.kubernetes.io/revision: 2
Selector:               app=deploy-myapp
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=deploy-myapp
  Containers:
   nginx-demo:
    Image:        nginx:1.20
    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-demo-5fffb97845 (2/2 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  39m   deployment-controller  Scaled up replica set deployment-demo-845c747588 to 2
  Normal  ScalingReplicaSet  12m   deployment-controller  Scaled up replica set deployment-demo-5fffb97845 to 1
  Normal  ScalingReplicaSet  12m   deployment-controller  Scaled down replica set deployment-demo-845c747588 to 1
  Normal  ScalingReplicaSet  12m   deployment-controller  Scaled up replica set deployment-demo-5fffb97845 to 2
  Normal  ScalingReplicaSet  12m   deployment-controller  Scaled down replica set deployment-demo-845c747588 to 0