K8S中的标签使用

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标签可以用于管理Pod，对Pod进行分类处理，比如多个Pod运行多个MSC网元，另外多个Pod运行CUDB网元，那么可以给这些Pod指定Type标签，对于MSC网元的版本也可能不同，所以还可以指定Version标签。标签对于K8S中的可操作元素的归类和管理具有重要意义。

创建带标签的Pod

创建Pod时，将yaml文件加入Label字段，此处加入app叫myweb，ver版本为v2。使用kubectl create创建Pod。

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apiVersion: v1
kind: Pod
metadata:
  name: myweb
  labels:
    app: myweb
    ver: v2
spec:
  restartPolicy: OnFailure
  containers:
  - name: myweb
    image: mywebv1
    imagePullPolicy: Never
    ports:
    - containerPort: 80
      protocol: TCP

查看最新创建的Pod，

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[root@master ~]# kubectl get pod -L app,ver
NAME                        READY   STATUS    RESTARTS   AGE     APP     VER
myweb                       1/1     Running   0          125m    myweb   v2
mywebv1                     1/1     Running   1          14d

[root@master ~]# kubectl get pod --show-labels
NAME                        READY   STATUS    RESTARTS   AGE     LABELS
myweb                       1/1     Running   0          126m    app=myweb,ver=v2
mywebv1                     1/1     Running   1          14d     <none>

修改现有的Pod标签

使用指令kubectl label即可修改现有Pod的标签。例如，

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[root@master ~]# kubectl label po mywebv1 app=myweb
Pod/mywebv1 labeled
[root@master ~]# kubectl get Pod -L app,ver
NAME                        READY   STATUS    RESTARTS   AGE     APP     VER
myweb                       1/1     Running   0          131m    myweb   v2
mywebv1                     1/1     Running   1          14d     myweb
[root@master ~]# kubectl label po mywebv1 ver=v1
Pod/mywebv1 labeled
[root@master ~]# kubectl get Pod -L app,ver
NAME                        READY   STATUS    RESTARTS   AGE     APP     VER
myweb                       1/1     Running   0          131m    myweb   v2
mywebv1                     1/1     Running   1          14d     myweb   v1

按照指定的Label查看Pod

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[root@master ~]# kubectl get po -l app=myweb --show-labels
NAME      READY   STATUS    RESTARTS   AGE    LABELS
myweb     1/1     Running   0          134m   app=myweb,ver=v2
mywebv1   1/1     Running   1          14d    app=myweb,ver=v1

[root@master ~]# kubectl get po -l '!app' --show-labels
NAME                        READY   STATUS    RESTARTS   AGE     LABELS

按照指定的Label删除Pod

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[root@master ~]# kubectl get po --show-labels
NAME                        READY   STATUS    RESTARTS   AGE     LABELS
my-nginx-86459cfc9f-fq7rt   1/1     Running   0          4h27m   pod-template-hash=86459cfc9f,run=my-nginx
my-nginx-86459cfc9f-s282t   1/1     Running   0          4h27m   pod-template-hash=86459cfc9f,run=my-nginx
myweb                       1/1     Running   0          170m    app=myweb,ver=v2
mywebv1                     1/1     Running   1          14d     app=myweb,ver=v1
mywebv3                     1/1     Running   0          14m     app=myweb,ver=v3

[root@master ~]# kubectl delete po -l app=myweb
pod "myweb" deleted
pod "mywebv1" deleted
pod "mywebv3" deleted

[root@master ~]# kubectl get po --show-labels
NAME                        READY   STATUS    RESTARTS   AGE     LABELS
my-nginx-86459cfc9f-fq7rt   1/1     Running   0          4h27m   pod-template-hash=86459cfc9f,run=my-nginx
my-nginx-86459cfc9f-s282t   1/1     Running   0          4h27m   pod-template-hash=86459cfc9f,run=my-nginx

给Node打Label

跟Pod操作一样，也可以给Node打标签，

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[root@master ~]# kubectl label node nodeb gpu=true
node/nodeb labeled

[root@master ~]# kubectl get node --show-labels
NAME     STATUS   ROLES    AGE   VERSION   LABELS
...
nodeb    Ready    <none>   18d   v1.14.2   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,gpu=true ...

创建Pod时，选择指定标签的Node。

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spec:
  nodeSelector: 
    gpu: "true"