[따배쿠] Label

Label

• Node를 포함하여 pod, deployment 등 모든 리소스에 할당 가능
• 리소스의 특성을 분류할 목적으로 사용
• Selector를 이용해서 선택
• Key-Value 한 쌍으로 적용

 

Label과 Selector

 

Label 관리 명령어

예시

 

# cmd 용도 pod 생성

root@master:~# kubectl run cmdpod --image=nginx:1.14 --port=80
pod/cmdpod created

 

# pod1.yaml 생성 (label X)

root@master:~/Getting-Start-Kubernetes/9# cat > pod1.yaml
apiVersion: v1
kind: Pod
metadata:
  name: pod-demo
spec:
  containers:
  - name: nginx
    image: nginx:1.14
    ports:
    - containerPort: 80

 

# pod2.yaml 생성 (label O)

root@master:~/Getting-Start-Kubernetes/9# vi pod2.yaml
apiVersion: v1
kind: Pod
metadata:
  name: label-pod-demo
  labels:
    name: mainui
    rel: stable
spec:
  containers:
  - name: nginx
    image: nginx:1.14
    ports:
    - containerPort: 80

 

# pod1 및 pod2 생성

root@master:~/Getting-Start-Kubernetes/9# kubectl create -f pod1.yaml -f pod2.yaml
pod/pod-demo created
pod/label-pod-demo created

 

# 확인

root@master:~/Getting-Start-Kubernetes/9# kubectl get pods --show-labels
NAME             READY   STATUS    RESTARTS   AGE     LABELS
cmdpod           1/1     Running   0          7m14s   run=cmdpod
label-pod-demo   1/1     Running   0          91s     name=mainui,rel=stable
pod-demo         1/1     Running   0          91s     <none>

 

label 정보를 표시한 pod 조회

- cmdpod : command line에서 실행한 pod는 자동으로 label이 할당된다. (run=cmdpod)- l

- label-pod-demo : label을 할당한 pod (name=mainui, rel=stable)

- pod-demo : label을 할당하지 않은 pod

 

# 활용

root@master:~/Getting-Start-Kubernetes/9# kubectl get pods -l name=mainui
NAME             READY   STATUS    RESTARTS   AGE
label-pod-demo   1/1     Running   0          4m18s

root@master:~/Getting-Start-Kubernetes/9# kubectl get pods --selector name=mainui
NAME             READY   STATUS    RESTARTS   AGE
label-pod-demo   1/1     Running   0          5m24s

 

*kubectl get [리소스 타입] -l name=[label명] : 해당 label명을 가진 pod 출력 (selector의 기능과 동일)

*kubectl get [리소스 타입] --selector name=[label명] : : 해당 label명을 가진 pod 출력

 

# command line으로 label 할당

root@master:~/Getting-Start-Kubernetes/9# kubectl label pod pod-demo name=test
pod/pod-demo labeled

root@master:~/Getting-Start-Kubernetes/9# kubectl get pods --show-labels
NAME             READY   STATUS    RESTARTS   AGE     LABELS
cmdpod           1/1     Running   0          13m     run=cmdpod
label-pod-demo   1/1     Running   0          7m46s   name=mainui,rel=stable
pod-demo         1/1     Running   0          7m46s   name=test

 

 

*kubectl label [리소스 타입] [리소스 명] [key=value] : key:value라는 label을 리소스에 할당

 

# label 변경

root@master:~/Getting-Start-Kubernetes/9# kubectl label pod pod-demo name=login
error: 'name' already has a value (test), and --overwrite is false

 

이미 name=test라는 label이 할당되어있는데, label을 변경하려고 하면 되지 않는다.

root@master:~/Getting-Start-Kubernetes/9# kubectl label pod pod-demo name=login --overwrite
pod/pod-demo labeled

root@master:~/Getting-Start-Kubernetes/9# kubectl get pods --show-labels
NAME             READY   STATUS    RESTARTS   AGE   LABELS
cmdpod           1/1     Running   0          17m   run=cmdpod
label-pod-demo   1/1     Running   0          11m   name=mainui,rel=stable
pod-demo         1/1     Running   0          11m   name=login

 

*kubectl label [리소스 타입] [리소스 명] [key=value] --overwrite : 이미 할당된 Key의 label 변경

이럴때 --overwirte 옵션을 붙여주면 정상적으로 overwrite 된다.

 

# label 복수 할당

root@master:~/Getting-Start-Kubernetes/9# kubectl label pod cmdpod name=order rel=beta
pod/cmdpod labeled
root@master:~/Getting-Start-Kubernetes/9# kubectl get pods --show-labels
NAME             READY   STATUS    RESTARTS   AGE   LABELS
cmdpod           1/1     Running   0          19m   name=order,rel=beta,run=cmdpod
label-pod-demo   1/1     Running   0          14m   name=mainui,rel=stable
pod-demo         1/1     Running   0          14m   name=login

*kubectl label [리소스 타입] [리소스 명] [key=value][key=value] … : label을 복수 할당하고 싶을 때는 이어서 작성해주면 된다.

 

# label 삭제

root@master:~/Getting-Start-Kubernetes/9# kubectl get pods --show-labels
NAME             READY   STATUS    RESTARTS   AGE   LABELS
cmdpod           1/1     Running   0          21m   name=order,rel=beta,run=cmdpod
label-pod-demo   1/1     Running   0          15m   name=mainui,rel=stable
pod-demo         1/1     Running   0          15m   name=login

root@master:~/Getting-Start-Kubernetes/9# kubectl label pod cmdpod run-
pod/cmdpod unlabeled

root@master:~/Getting-Start-Kubernetes/9# kubectl get pods --show-labels
NAME             READY   STATUS    RESTARTS   AGE   LABELS
cmdpod           1/1     Running   0          22m   name=order,rel=beta
label-pod-demo   1/1     Running   0          16m   name=mainui,rel=stable
pod-demo         1/1     Running   0          16m   name=login

 

 * label명 뒤에 - (대시) : label 삭제 

 

# 활용

root@master:~/Getting-Start-Kubernetes/9# kubectl label pod pod-demo rel=stable
pod/pod-demo labeled

root@master:~/Getting-Start-Kubernetes/9# kubectl get pods --show-labels
NAME             READY   STATUS    RESTARTS   AGE   LABELS
cmdpod           1/1     Running   0          23m   name=order,rel=beta
label-pod-demo   1/1     Running   0          18m   name=mainui,rel=stable
pod-demo         1/1     Running   0          18m   name=login,rel=stable

root@master:~/Getting-Start-Kubernetes/9# kubectl get pods --selector rel=stable
NAME             READY   STATUS    RESTARTS   AGE
label-pod-demo   1/1     Running   0          18m
pod-demo         1/1     Running   0          18m

root@master:~/Getting-Start-Kubernetes/9# kubectl get pods --selector rel=beta
NAME     READY   STATUS    RESTARTS   AGE
cmdpod   1/1     Running   0          24m

 

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참고 영상

https://www.youtube.com/watch?v=yf5syEBAg2Y&list=PLApuRlvrZKohaBHvXAOhUD-RxD0uQ3z0c&index=30