Kubernetes基础：给Pod加上Label

这篇文章以具体的例子来介绍如何在Pod实例上添加Label。

示例说明

比如如下在一个名为dev-pod的Pod上添加一个Label，Label的内容是：environment: dev

[root@host131 Pod]# cat pod-with-labels.yaml 
---
apiVersion: v1
kind: Pod
metadata:
  name: dev-pod
  namespace: default
  labels:
    environment: dev
spec:
  containers:
  - name: dev-pod-host
    image: liumiaocn/tornado:latest
    command: ["python"]
    args: ["/usr/local/bin/daemon.py", "in dev environment"]
    ports:
        - containerPort: 80
...
[root@host131 Pod]#

Pod生成并确认

[root@host131 Pod]# kubectl create -f pod-with-labels.yaml 
pod/dev-pod created
[root@host131 Pod]# kubectl get pods -o wide
NAME      READY   STATUS    RESTARTS   AGE   IP             NODE              NOMINATED NODE   READINESS GATES
dev-pod   1/1     Running   0          6s    10.254.152.5   192.168.163.131   <none>           <none>
[root@host131 Pod]#

多个Pod

给多个Pod都添加上environment的标签

[root@host131 Pod]# cat pod-with-labels.yaml 
---
apiVersion: v1
kind: Pod
metadata:
  name: dev-pod
  namespace: default
  labels:
    environment: dev
spec:
  containers:
  - name: dev-pod-host
    image: liumiaocn/tornado:latest
    command: ["python"]
    args: ["/usr/local/bin/daemon.py", "in dev environment"]
    ports:
        - containerPort: 80
...

---
apiVersion: v1
kind: Pod
metadata:
  name: test-pod
  namespace: default
  labels:
    environment: test
spec:
  containers:
  - name: test-pod-host
    image: liumiaocn/tornado:latest
    command: ["python"]
    args: ["/usr/local/bin/daemon.py", "in test environment"]
    ports:
        - containerPort: 80
...

---
apiVersion: v1
kind: Pod
metadata:
  name: prod-pod
  namespace: default
  labels:
    environment: prod
spec:
  containers:
  - name: prod-pod-host
    image: liumiaocn/tornado:latest
    command: ["python"]
    args: ["/usr/local/bin/daemon.py", "in prod environment"]
    ports:
        - containerPort: 80
...
[root@host131 Pod]# 

Pod生成与结果确认

[root@host131 Pod]# kubectl create -f pod-with-labels.yaml 
pod/dev-pod created
pod/test-pod created
pod/prod-pod created
[root@host131 Pod]# 
[root@host131 Pod]# kubectl get pods -o wide
NAME       READY   STATUS    RESTARTS   AGE   IP             NODE              NOMINATED NODE   READINESS GATES
dev-pod    1/1     Running   0          7s    10.254.152.5   192.168.163.131   <none>           <none>
prod-pod   1/1     Running   0          7s    10.254.152.7   192.168.163.131   <none>           <none>
test-pod   1/1     Running   0          7s    10.254.152.6   192.168.163.131   <none>           <none>
[root@host131 Pod]# 

kubectl命令中使用标签

使用-l或者--selector即可进行查询了

• 查询environment为dev的Pod信息

[root@host131 Pod]# kubectl get pods -l environment=dev -o wide
NAME      READY   STATUS    RESTARTS   AGE     IP             NODE              NOMINATED NODE   READINESS GATES
dev-pod   1/1     Running   0          4m43s   10.254.152.5   192.168.163.131   <none>           <none>
[root@host131 Pod]# 

• 查询environment为prod的Pod信息

[root@host131 Pod]# kubectl get pods --selector environment=prod -o wide
NAME       READY   STATUS    RESTARTS   AGE     IP             NODE              NOMINATED NODE   READINESS GATES
prod-pod   1/1     Running   0          5m14s   10.254.152.7   192.168.163.131   <none>           <none>
[root@host131 Pod]#

• 查询environment为prod之外的Pod信息

[root@host131 Pod]# kubectl get pods -l environment!=prod -o wide
NAME       READY   STATUS    RESTARTS   AGE    IP             NODE              NOMINATED NODE   READINESS GATES
dev-pod    1/1     Running   0          6m9s   10.254.152.5   192.168.163.131   <none>           <none>
test-pod   1/1     Running   0          6m9s   10.254.152.6   192.168.163.131   <none>           <none>
[root@host131 Pod]# 

修改Pod的Label

比如事先又如下Pod

[root@host131 ReplicaSet]# kubectl get pods -o wide 
NAME            READY   STATUS    RESTARTS   AGE     IP             NODE              NOMINATED NODE   READINESS GATES
test-rs-7c27t   1/1     Running   0          6m55s   10.254.152.5   192.168.163.131   <none>           <none>
[root@host131 ReplicaSet]#

此Pod的Label信息如下所示：

[root@host131 ReplicaSet]# kubectl describe pod test-rs-7c27t |grep Labels:
Labels:       app=busybox-prod
[root@host131 ReplicaSet]# 

修改命令：kubectl label pod Pod名称 修改后的Label内容 --overwrite

执行示例和结果确认如下所示：

[root@host131 ReplicaSet]# kubectl label pod test-rs-7c27t app=busybox-dev --overwrite
pod/test-rs-7c27t labeled
[root@host131 ReplicaSet]# 
[root@host131 ReplicaSet]# kubectl describe pod test-rs-7c27t |grep Labels:
Labels:       app=busybox-dev
[root@host131 ReplicaSet]# 

总结

相同的Label可以添加在不同的资源上，同一资源可以设定多个Label，在使用时可以根据Lable进行资源选择，可以根据需要灵活使用。