
<1> 실습 환경


1
서울리전으로 변경


2
cloudformation으로 명령서버 1대 생성


3.36.103.152
aws-1130-key


3
aws s3 ls

Unable to locate credentials. You can configure credentials by running "aws login".
[root@kops-ec2 ~]#


4
# iam

access-key , secret-key 확인


5
# 권한 설정

aws configure


ap-northeast-2

<엔터>



aws s3 ls



6



cat <<EOF > eks-freetier-setup.yaml
apiVersion: eksctl.io/v1alpha5
kind: ClusterConfig

metadata:
  name: free-vpc-cluster
  region: ap-northeast-2
  version: "1.34"

vpc:
  clusterEndpoints:
    publicAccess: true
    privateAccess: true
  nat:
    gateway: Single # 비용 절감을 위해 NAT 게이트웨이를 1개만 생성 (중요!)

managedNodeGroups:
  - name: standard-nodes
    # --- 인스턴스 타입 선택 가이드 ---
    # 1. t3.micro : 프리티어 대상 (단, K8s 시스템 Pod 실행 시 리소스가 매우 부족할 수 있음)
    # 2. t3.small : 가성비 추천 (시스템 안정성 확보)
    # 3. c7i-flex.large (2cpu/4gb) : 연산 위주
    # 4. m7i-flex.large (2cpu/8gb) : 메모리 여유
    instanceType: t3.small
    
    minSize: 1
    maxSize: 2
    desiredCapacity: 1 # 비용 절감을 위해 노드 수를 1대로 시작 (필요 시 증가)
    privateNetworking: true
    iam:
      withAddonPolicies:
        imageBuilder: true
        autoScaler: true
        cloudWatch: true

# 필수 애드온만 설치
addons:
  - name: vpc-cni
  - name: coredns
  - name: kube-proxy
EOF

# 클러스터 생성 시작

eksctl create cluster -f eks-freetier-setup.yaml



(15분)



# 특정 네임스페이스에서 비정상적인 Pod만 골라보기
kubectl get pods -A --field-selector=status.phase!=Running

# 최근 발생한 클러스터 전체 이벤트 시간순 정렬
kubectl get events -A --sort-by='.lastTimestamp'




<2> 시나리오: "웹 브라우저에서 서비스 접속이 안 돼요!"

watch -d kubectl get ep,no,deploy,rs,pods


kubectl get pods -l app=my-web


kubectl get endpoints my-web-service



# 디버깅용 포드 생성
kubectl run curl-test --image=curlimages/curl -i --tty --rm

# 내부에서 서비스 이름으로 호출
curl http://my-web-service:8080



kubectl describe node <pod-가-떠있는-노드-이름>



<3> 실습 시나리오: "유령 서비스 찾기"

1
watch -d kubectl get ep,no,deploy,rs,pods




2

먼저 아래 YAML을 복사해 trouble-test.yaml로 저장하고 적용하세요.


trouble-test.yaml


apiVersion: v1
kind: Pod
metadata:
  name: my-web-pod
  labels:
    app: nginx-frontend  # Pod의 라벨
spec:
  containers:
  - name: nginx
    image: nginx:1.14.2
    ports:
    - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: my-web-service
spec:
  selector:
    app: nginx-web      # (오류 지점) Pod 라벨과 일치하지 않음
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80



kubectl apply -f trouble-test.yaml 

명령어로 실행합니다.


3
kubectl get pods


kubectl run busybox --image=busybox -it --rm -- restart=Never -- wget -O- http://my-web-service



kubectl get endpoints my-web-service


NAME                       ENDPOINTS                                AGE
endpoints/kubernetes       192.168.107.75:443,192.168.162.108:443   33m
endpoints/my-web-service   <none>        


# 서비스를 직접 수정하거나 YAML 수정 후 재배포
kubectl patch svc my-web-service -p '{"spec":{"selector":{"app":"nginx-frontend"}}}'

      AGE
endpoints/kubernetes       192.168.107.75:443,192.168.162.108:443   34m
endpoints/my-web-service   192.168.134.94:80                        2m51s


4
k delete pod/my-web-pod






<4>실습: CrashLoopBackOff 탈출하기


1

cat <<EOF > crash-test.yaml
apiVersion: v1
kind: Pod
metadata:
  name: error-pod
  labels:
    app: buggy-app
spec:
  containers:
  - name: nginx-container
    image: nginx:latest
    command: ["bin/sh", "-c"]
    # 존재하지 않는 환경 변수를 참조하여 즉시 종료되도록 유도
    args: ["echo \$REQUIRED_VAR && nginx -g 'daemon off;'"]
    env:
    - name: WRONG_VAR
      value: "I am wrong"
EOF

kubectl apply -f crash-test.yaml




2

kubectl get pod error-pod

# kubectl get pod error-pod
NAME        READY   STATUS    RESTARTS   AGE
error-pod   1/1     Running   0          19s



kubectl logs error-pod


kubectl describe pod error-pod



3


cat <<EOF > crash-test.yaml
apiVersion: v1
kind: Pod
metadata:
  name: error-pod
  labels:
    app: buggy-app
spec:
  containers:
  - name: nginx-container
    image: nginx:latest
    command: ["/bin/sh", "-c"]
    args: ["echo \$REQUIRED_VAR && nginx -g 'daemon off;'"]
    env:
    - name: REQUIRED_VAR
      value: "Hello, Kubernetes! Now I am working."
EOF

# 수정된 설정 적용
kubectl apply -f crash-test.yaml --force





4
kubectl get pod error-pod -w

NAME        READY   STATUS    RESTARTS   AGE
error-pod   1/1     Running   0          7s



5

성공 로그 확인: kubectl logs error-pod 실행 시 "Hello, Kubernetes!..." 문구가 보이면 성공입니다


kubectl logs error-pod



(ssss@free-vpc-cluster:N/A) [root@kops-ec2 ~]# kubectl logs error-pod
Hello, Kubernetes! Now I am working.
2026/02/18 09:41:01 [notice] 7#7: using the "epoll" event method
2026/02/18 09:41:01 [notice] 7#7: nginx/1.29.5
2026/02/18 09:41:01 [notice] 7#7: built by gcc 14.2.0 (Debian 14.2.0-19)
2026/02/18 09:41:01 [notice] 7#7: OS: Linux 6.12.66-88.122.amzn2023.x86_64
2026/02/18 09:41:01 [notice] 7#7: getrlimit(RLIMIT_NOFILE): 65536:1048576
2026/02/18 09:41:01 [notice] 7#7: start worker processes
2026/02/18 09:41:01 [notice] 7#7: start worker process 8
2026/02/18 09:41:01 [notice] 7#7: start worker process 9



6

 k delete pod/error-pod








<5> 실습: "자리가 없어서 못 들어가는 Pod" (Pending)



1

cat <<EOF > greedy-pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: greedy-pod
spec:
  containers:
  - name: nginx
    image: nginx
    resources:
      requests:
        cpu: "100"    # 일반적인 노드에는 존재하지 않는 CPU 양
        memory: "100Gi"
EOF

kubectl apply -f greedy-pod.yaml



2

kubectl get pod greedy-pod


   RESTARTS   AGE
pod/greedy-pod   0/1     Pending   0          4s





3
kubectl describe pod greedy-pod


Events:
  Type     Reason            Age   From               Message
  ----     ------            ----  ----               -------
  Warning  FailedScheduling  20s   default-scheduler  0/1 nodes are available: 1 Insufficient cpu, 1 Insufficient memory. no new claims to deallocate, preemption: 0/1 nodes are available: 1 Preemption is not helpful for scheduling.
(ssss@free-vpc-cluster:N/A) [root@kops-ec2 ~]#






4

cat <<EOF > greedy-pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: greedy-pod
spec:
  containers:
  - name: nginx
    image: nginx
    resources:
      requests:
        cpu: "100m"    # 0.1 코어로 수정
        memory: "128Mi"
EOF

# 기존 포드 삭제 후 재배포 (또는 apply)
kubectl apply -f greedy-pod.yaml --force



5

kubectl get pod greedy-pod -w


NAME             READY   STATUS    RESTARTS   AGE
pod/greedy-pod   1/1     Running   0          9s



6

# 각 노드별 자원 할당량(CPU/메모리) 요약 확인
kubectl describe nodes | grep -A 7 "Allocated resources"



ss@free-vpc-cluster:N/A) [root@kops-ec2 ~]# kubectl describe nodes | grep -A 7 "Allocated resources"
Allocated resources:
  (Total limits may be over 100 percent, i.e., overcommitted.)
  Resource           Requests     Limits
  --------           --------     ------
  cpu                650m (33%)   0 (0%)
  memory             668Mi (46%)  1140Mi (79%)
  ephemeral-storage  0 (0%)       0 (0%)
  hugepages-1Gi      0 (0%)       0 (0%)
(ssss@free-vpc-cluster:N/A) [root@kops-ec2 ~]#