Exercise 8.1: Troubleshooting: Monitor Applications

1. Pod 생성

   cat <<EOF | kubectl create -f -
   apiVersion: v1
   kind: Pod
   metadata:
     name: demo
   spec:
     containers:
     - name: busybox
       image: busybox
       command: [ "sleep" ]
       args: [ "10" ]
     - name: web
       image: nginx
       livenessProbe:
         httpGet:
           path: /
           port: 80
         initialDelaySeconds: 3
         periodSeconds: 3
   EOF

2. Pod 상태 확인

   kubectl get pod demo

3. Pod 상세 내용 확인

   kubectl describe pod demo

4. 컨테이너 로그 확인

   {
       kubectl logs demo busybox
       kubectl logs demo web
   }

5. Pod 상태 확인

   kubectl get pod demo

6. Pod 삭제

   kubectl delete pod demo

7. Pod 생성

   cat <<EOF | kubectl create -f -
   apiVersion: v1
   kind: Pod
   metadata:
     name: busybox
   spec:
     containers:
     - name: busybox
       image: busybox
       command: [ "sleep" ]
       args: [ "3600" ]
       securityContext:
         runAsUser: 2000
   EOF

8. 생성한 Pod로 Shell 연결

   kubectl exec -it busybox -- /bin/sh

9. DNS 서버 동작 확인

   nslookup www.linuxfoundation.org

10. 로컬 DNS 설정 정보 확인

    cat /etc/resolv.conf

11. 외부 연결 테스트

    nc www.linux.com 25
    wget http://www.linux.com

12. Shell 프로세스 종료

    exit

13. Pod 삭제

    kubectl delete pod busybox

14. 데모 애플리케이션 배포

    cat <<EOF | kubectl apply -f -
    apiVersion: v1
    kind: Namespace
    metadata:
      name: demo
    ---
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: nginx
      labels:
        app: nginx
      namespace: demo
    spec:
      selector:
        matchLabels:
          app: nginx
      replicas: 3
      template:
        metadata:
          labels:
            app: nginx
        spec:
          containers:
          - image: nginx:1.20.1
            name: nginx
            ports:
            - containerPort: 80
              protocol: TCP
    ---
    apiVersion: v1
    kind: Service
    metadata:
      name: nginx
      namespace: demo
    spec:
      type: NodePort
      selector:
        app: nginx
      ports:
        - port: 80
    EOF

15. 생성된 Service 및 Endpoint 확인

    kubectl get svc,ep -n demo

16. kube-proxy가 실행중인지 확인

    ps -elf |grep kube-proxy

17. kube-proxy 로그 확인

    sudo journalctl -a | grep proxy
    kubectl -n kube-system logs ds/kube-proxy

18. iptable 규칙 확인

    sudo iptables-save |grep nginx

19. 위에서 확인한 NodePort로 접근 확인

    curl localhost:NODE_PORT