九、K8S-label和label Selector

label和label selector 标签和标签选择器

1、label 标签： 一个label就是一个key/value对

        label 特性：

1. label可以被附加到各种资源对象上
2. 一个资源对象可以定义任意数量的label
3. 同一个label可以被添加到任意数量的资源上

2、label selector 标签选择器

        Label selector是Kubernetes核心的分组机制，通过label selector客户端/用户能够识别一组有共同特征或属性的资源对象。

查询条件：

selector:

matchLabels:

app: myweb

matchExpressions:- {key: tier, operator: In, values: [frontend]}- {key: environment, operator: NorIn, values: [dev]}

        matchLabels用于定义一组Label，与直接写在Selector中作用相同：matchExpression用于定义一组基于集合的筛选条件，可用的条件运算符包括：In、NotIn、Exists和DoesNotExist。

        如果同时设置了matchLabels和matchExpression，则两组条件为“AND”关系，即所有条件需要满足才能完成Selector的筛选。

3、示例

• 定义标签

#可以多创建几个deploy 方便演示
[root@k8s-master-1 test]# vim deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: label-test
spec:
  selector:
    matchLabels:
      app: nginx
      env: prod
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
        env: prod
    spec:
      containers:
      - image: nginx:1.17.1
        name: nginx

[root@k8s-master-1 test]# kubectl apply -f deployment.yaml 
deployment.apps/label-test created
#创建完成就可以看到他的标签
[root@k8s-master-1 test]# kubectl get pod --show-labels
NAME                          READY   STATUS    RESTARTS   AGE   LABELS

label-test-7787b4694b-jvrz5   1/1     Running   0          16s   app=nginx,env=prod,pod-template-hash=7787b4694b

[root@k8s-master-1 test]# kubectl get pod --show-labels -owide
NAME                          READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES   LABELS

label-test-7787b4694b-jvrz5   1/1     Running   0          46s   10.244.0.164   k8s-node-1                          app=nginx,env=prod,pod-template-hash=7787b4694b

#查看所有标签  -A
[root@k8s-master-1 ~]# kubectl get pod -A --show-labels
NAMESPACE     NAME                                    READY   STATUS    RESTARTS   AGE     LABELS
default       busybox                                 1/1     Running   11         2d17h   
default       label-test-7787b4694b-jvrz5             1/1     Running   2          41h     app=nginx,env=prod,pod-template-hash=7787b4694b
default       web-96d5df5c8-vmxgr                     1/1     Running   2          2d23h   app=web,pod-template-hash=96d5df5c8
kube-system   coredns-6b774d79bb-4ssxb                1/1     Running   48         18d     k8s-app=kube-dns,pod-template-hash=6b774d79bb
kube-system   kube-flannel-ds-amd64-7bpfs             1/1     Running   16         18d     app=flannel,controller-revision-hash=76ccd4ff4f,pod-template-generation=1,tier=node
kube-system   kube-flannel-ds-amd64-8d8fj             1/1     Running   17         18d     app=flannel,controller-revision-hash=76ccd4ff4f,pod-template-generation=1,tier=node
kube-system   kubernetes-dashboard-567f98444d-d9zb4   1/1     Running   2          2d23h   k8s-app=kubernetes-dashboard,pod-template-hash=567f98444d
kube-system   metrics-server-6f6c655778-66q5g         1/1     Running   2          2d23h   k8s-app=metrics-server,pod-template-hash=6f6c655778
kube-system   metrics-server-6f6c655778-m6r7g         1/1     Running   3          3d17h   k8s-app=metrics-server,pod-template-hash=6f6c655778

#命令行方式给容器、node节点、deploy、等等添加标签
[root@k8s-master-1 ~]# kubectl label node k8s-node01 k8s-node02 env=test
[root@k8s-master-1 ~]# kubectl label pod busybox app=v1
pod/busybox labeled

[root@k8s-master-1 ~]# 
[root@k8s-master-1 ~]# kubectl get pod --show-labels
NAME                          READY   STATUS    RESTARTS   AGE     LABELS
busybox                       1/1     Running   11         2d18h   app=v1

[root@k8s-master-1 ~]# 
##修改标签使用  --overwrite
[root@k8s-master-1 ~]# kubectl label pod busybox app=v2 --overwrite
pod/busybox labeled
[root@k8s-master-1 ~]# 

[root@k8s-master-1 ~]# kubectl get pod --show-labels
NAME                          READY   STATUS    RESTARTS   AGE     LABELS
busybox                       1/1     Running   11         2d18h   app=v2
#删除标签
[root@k8s-master-1 ~]# kubectl label pod busybox app-
pod/busybox labeled

• label selector

         命令行方式过滤

1、过滤出所有包含env=prod的pod
[root@k8s-master-1 test]# kubectl get pod -l env=prod --show-labels
NAME                          READY   STATUS    RESTARTS   AGE   LABELS
label-test-7787b4694b-jvrz5   1/1     Running   0          34m   app=nginx,env=prod,pod-template-hash=7787b4694b
2、过滤出包含env=prod，app=nginx的pod
[root@k8s-master-1 test]# kubectl get pod -l 'env=prod,app=nginx' --show-labels
NAME                          READY   STATUS    RESTARTS   AGE   LABELS
label-test-7787b4694b-jvrz5   1/1     Running   0          38m   app=nginx,env=prod,pod-template-hash=7787b4694b
'env=prod,app in (nginx,nginx02,nginx03)'，逗号分隔2个条件，表示要同时的满足
3、过滤出来不包含app=nginx1和app=nginx3的pod。语法：'app notin (nginx,nginx03)' ，用notin来实现
[root@k8s-master-1 test]# kubectl get pod -l 'app notin (nginx1,nginx2)' --show-labels
4、过滤出来不包含app=nginx的pod。  语法：'env != dev'
[root@k8s-master-1 test]# kubectl get pod -l 'app !=nginx' --show-labels
NAME                  READY   STATUS    RESTARTS   AGE   LABELS

web-96d5df5c8-vmxgr   1/1     Running   1          31h   app=web,pod-template-hash=96d5df5c8

4、yaml配置中的标签选择表达式

•  基于等式的匹配

创建一个service

[root@k8s-master-1 test]# vim deployment-service.yaml 
apiVersion: v1
kind: Service
metadata:
  name: service-label
spec:
  ports:
  - name: 80-80
    port: 80
    targetPort: 80
  selector: #标签选择器，选择标签为env: prod的pod
    env: prod
[root@k8s-master-1 test]# kubectl apply -f deployment-service.yaml 
service/service-label created
[root@k8s-master-1 test]# kubectl get svc service-label -owide
NAME            TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE    SELECTOR

service-label   ClusterIP   10.0.0.254           80/TCP    6m8s   env=prod
# 如下图，可以看到，service恰好就是关联到了这2个pod上了。
[root@k8s-master-1 ~]# kubectl get endpoints service-label
NAME            ENDPOINTS                         AGE
service-label   10.244.0.166:80,10.244.0.167:80   5h18m
[root@k8s-master-1 ~]# 
[root@k8s-master-1 ~]# 
[root@k8s-master-1 ~]# kubectl get pod -l env=prod -owide
NAME                          READY   STATUS    RESTARTS   AGE    IP             NODE         NOMINATED NODE   READINESS GATES
busybox                       1/1     Running   18         3d1h   10.244.0.166   k8s-node-1              
label-test-7787b4694b-jvrz5   1/1     Running   2          2d1h   10.244.0.167   k8s-node-1              

• 基于集合的匹配

注意：job、deployment、replicaset、daemonset不仅仅支持基于等式的匹配，也支持基于集合的匹配

如第三个步骤，创建的deployment，matchlabels用于匹配一组的标签，与直接在selector中的作用相同

在yaml文件中基于集合的方式匹配
语法：
spec:  #  
  selector:#
    matchLabels: #matchlabels用于匹配一组的标签，与直接在selector中的作用相同
      app: nginx06#
      env: online#

[root@k8s-master-1 test]# 
[root@k8s-master-1 test]#  kubectl get deployment label-test -owide
NAME         READY   UP-TO-DATE   AVAILABLE   AGE    CONTAINERS   IMAGES         SELECTOR
label-test   1/1     1            1           2d1h   nginx        nginx:1.17.1   app=nginx,env=prod

[root@k8s-master-1 test]# kubectl get pod -owide
NAME                          READY   STATUS    RESTARTS   AGE    IP             NODE         NOMINATED NODE   READINESS GATES
busybox                       1/1     Running   18         3d1h   10.244.0.166   k8s-node-1              
label-test-7787b4694b-jvrz5   1/1     Running   2          2d1h   10.244.0.167   k8s-node-1              


[root@k8s-master-1 test]# 
[root@k8s-master-1 test]# kubectl get pod label-test-7787b4694b-jvrz5 -owide --show-labels
NAME                          READY   STATUS    RESTARTS   AGE    IP             NODE         NOMINATED NODE   READINESS GATES   LABELS
label-test-7787b4694b-jvrz5   1/1     Running   2          2d1h   10.244.0.167   k8s-node-1                          app=nginx,env=prod,pod-template-hash=7787b4694b

#这样，deployment就和要控制、管理的pod进行了关联。

另外，在集合的方式里，matchExpression也可以作为匹配的操作
spec:  
  selector:
    matchLabels:
      app: nginx06
      env: online
    matchExpressions:
     - {key: release, operator: In, values: [stable] }
     - {key: app,operator: NotIn, values: [nginx02,nginx03] }
语法：
    matchExpressions:
     - {key: release, operator: In, values: [stable] }
     - {key: app,operator: NotIn, values: [nginx02,nginx03] }