Deployment.spec.selector.matchLables实验解释

原文：https://cloud.tencent.com/developer/article/1394657

Deployment.spec.selector.matchLables实验解释

作者: 张首富
时间: 2019-02-23
个人博客: www.zhangshoufu.com
QQ群: 895291458

正确的Deployment,让matchLabels 和template.metadata.lables完全比配不报错

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
spec:
  selector:
    matchLabels:
      app: my-nginx
  replicas: 2
  template:
    metadata:
      labels:
        app: my-nginx
    spec:
      containers:
      - name: my-nginx
        image: nginx
        ports:
        - containerPort: 80

pod创建成功

[root@rke test_yaml]# kubectl get pods
NAME                      READY   STATUS    RESTARTS   AGE
my-nginx-9b44d8f5-d6n8z   1/1     Running   0          3s
my-nginx-9b44d8f5-zzv52   1/1     Running   0          3s

---

直接不写spec.mathlabels创建直接报错缺少缺少必要字段selector

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
spec:
  replicas: 2
  template:
    metadata:
      labels:
        run: my-nginx
    spec:
      containers:
      - name: my-nginx
        image: nginx
        ports:
        - containerPort: 80

运行报错结果如下:

[root@rke test_yaml]# kubectl create -f test_pod_svc.yaml
error: error validating "test_pod_svc.yaml": error validating data: ValidationError(Deployment.spec): missing required field "selector" in io.k8s.api.apps.v1.DeploymentSpec; if you choose to ignore these errors, turn validation off with --validate=false

---

#当把matchLables匹配的和下面pod模板不相对应,也会直接报错,选择的和模板标签不匹配

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
spec:
  selector:
    matchLabels:
      app: my-nginx-add
  replicas: 2
  template:
    metadata:
      labels:
        app: my-nginx
    spec:
      containers:
      - name: my-nginx
        image: nginx:1.14
        ports:
        - containerPort: 80

运行报错结果如下:

The Deployment "my-nginx" is invalid: spec.template.metadata.labels: Invalid value: map[string]string{"app":"my-nginx"}: `selector` does not match template `labels`

---

查看帮助手册

 kubectl explain Deployment.spec

    selector  <Object>
     Label selector for pods. Existing ReplicaSets whose pods are selected by
     this will be the ones affected by this deployment.

     pod的标签选择器。 由此选择其pod的现有ReplicaSet(副本集)将受此部署影响的副本。

---

#总结: 1,在Deployment中必须写matchLables, 2,在定义模板的时候必须定义labels,因为Deployment.spec.selector是必须字段,而他又必须和template.labels对应, 3,template里面定义的内容会应用到下面所有的副本集里面,在template.spec.containers里面不能定义labels标签.