[CKA] Service 란?

이번엔 Service 에 대해 정리하고자 한다.

 

1. 정의

- Pod 들을 안정적인 네트워크 엔드포인트로 묶어주는 오브젝트

  > Pod 집합 앞에 놓는 고정된 접근 지점 

 

2. 특징

- Pod 들의 고정 DNS / IP 제공

- Pod 라벨 셀렉터로 트래픽 라우팅

- 로드밸런싱

- 서비스 디스커버리 제공

 

3. 관련 문제 (KodeKloud 에서 제공하는 샘플 문제를 정리)

-  How many Services exist on the system?

kubectl get service

 

- How many labels are configured on the kubernetes service?

kubectl describe service kubernetes

 

- How many Deployments exist on the system now?

kubectl get deployment

 

- Create a new service to access the web application using the service-definition-1.yaml file.

  > Name: webapp-service / Type: NodePort / targetPort: 8080 / port: 8080 / nodePort: 30080 / selector:  name: simple-webapp

apiVersion: v1
kind: Service
metadata:
  name: webapp-service
  namespace: default
spec:
  ports:
  - nodePort: 30080
    port: 8080
    targetPort: 8080
  selector:
    name: simple-webapp
  type: NodePort

kubectl apply -f service-definition-1.yaml

 

- Create a service named redis-service to expose the existing redis pod within the cluster on port 6379.

kubectl expose pod redis --port=6379 --name=redis-service --type=ClusterIP

 

- Create a pod named httpd using the image httpd:alpine in the default namespace. Then, create a service of type ClusterIP with the same name (httpd) that exposes the pod on port 80.

kubectl run httpd --image=httpd:alpine --port=80 --expose

 

- Use kubectl explain with the --recursive flag to explore the service.spec.ports structure. Looking at the recursive output, which of these fields is not available under service.spec.ports?

kubectl explain service.spec.ports —recursive

 

 

4. 출처

- https://learn.kodekloud.com/user/courses/udemy-labs-certified-kubernetes-administrator-with-practice-tests