Kubernetes 기본 개념

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3                    # Pod 개수
  selector:
    matchLabels:
      app: nginx                 # 관리할 Pod 선택
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.21
        ports:
        - containerPort: 80
        resources:
          requests:
            memory: "64Mi"
            cpu: "250m"
          limits:
            memory: "128Mi"
            cpu: "500m"

# Deployment 생성
kubectl apply -f deployment.yaml

# 조회
kubectl get deployments
kubectl get pods -l app=nginx

# 스케일링
kubectl scale deployment nginx-deployment --replicas=5

# 이미지 업데이트 (Rolling Update)
kubectl set image deployment/nginx-deployment nginx=nginx:1.22

# 롤백
kubectl rollout undo deployment/nginx-deployment

# 배포 상태 확인
kubectl rollout status deployment/nginx-deployment

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: nginx-replicaset
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.21
        ports:
        - containerPort: 80

apiVersion: batch/v1
kind: Job
metadata:
  name: backup-job
spec:
  template:
    spec:
      containers:
      - name: backup
        image: busybox
        command: ["sh", "-c", "echo 'Backup completed' && sleep 10"]
      restartPolicy: Never
  backoffLimit: 3                # 실패 시 재시도 횟수

# Job 실행 및 확인
kubectl apply -f job.yaml
kubectl get jobs
kubectl logs job/backup-job

apiVersion: batch/v1
kind: CronJob
metadata:
  name: daily-backup
spec:
  schedule: "0 2 * * *"          # 매일 02:00
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: backup
            image: busybox
            command: ["sh", "-c", "date; echo 'Daily backup executed'"]
          restartPolicy: OnFailure
  successfulJobsHistoryLimit: 3  # 성공 기록 유지 개수
  failedJobsHistoryLimit: 1      # 실패 기록 유지 개수

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: fluentd-logging
spec:
  selector:
    matchLabels:
      name: fluentd
  template:
    metadata:
      labels:
        name: fluentd
    spec:
      tolerations:               # Master 노드에도 배포
      - key: node-role.kubernetes.io/master
        effect: NoSchedule
      containers:
      - name: fluentd
        image: fluent/fluentd:latest
        volumeMounts:
        - name: varlog
          mountPath: /var/log
      volumes:
      - name: varlog
        hostPath:
          path: /var/log

apiVersion: v1
kind: Service
metadata:
  name: nginx-clusterip
spec:
  type: ClusterIP              # 생략 가능 (기본값)
  selector:
    app: nginx
  ports:
  - port: 80                   # 서비스 포트
    targetPort: 80             # 컨테이너 포트

apiVersion: v1
kind: Service
metadata:
  name: nginx-nodeport
spec:
  type: NodePort
  selector:
    app: nginx
  ports:
  - port: 80
    targetPort: 80
    nodePort: 30080            # 30000-32767 범위

# 접근: http://<NODE_IP>:30080

apiVersion: v1
kind: Service
metadata:
  name: nginx-lb
spec:
  type: LoadBalancer
  selector:
    app: nginx
  ports:
  - port: 80
    targetPort: 80

# External IP 확인
kubectl get svc nginx-lb

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: app-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  ingressClassName: nginx
  rules:
  - host: app.example.com
    http:
      paths:
      - path: /api
        pathType: Prefix
        backend:
          service:
            name: api-service
            port:
              number: 80
      - path: /web
        pathType: Prefix
        backend:
          service:
            name: web-service
            port:
              number: 80

# Calico 설치 예시
kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml

# CNI 상태 확인
kubectl get pods -n kube-system | grep calico

# Taint 추가
kubectl taint nodes node1 gpu=true:NoSchedule

# Taint 제거
kubectl taint nodes node1 gpu=true:NoSchedule-

# Taint 확인
kubectl describe node node1 | grep Taint

apiVersion: v1
kind: Pod
metadata:
  name: gpu-pod
spec:
  tolerations:
  - key: "gpu"
    operator: "Equal"
    value: "true"
    effect: "NoSchedule"
  containers:
  - name: gpu-container
    image: nvidia/cuda:11.0-base

# 클러스터 정보
kubectl cluster-info
kubectl get nodes -o wide

# 리소스 조회
kubectl get all                          # 모든 리소스
kubectl get pods -A                      # 모든 네임스페이스
kubectl get pods -o wide                 # 상세 정보 (IP, Node 등)
kubectl get events --sort-by='.lastTimestamp'

# 상세 정보
kubectl describe pod <pod-name>
kubectl describe svc <service-name>

# 로그
kubectl logs <pod-name>
kubectl logs <pod-name> -c <container>   # 멀티 컨테이너
kubectl logs -f <pod-name>               # 실시간

# 디버깅
kubectl exec -it <pod-name> -- /bin/sh
kubectl port-forward svc/nginx 8080:80   # 로컬 포트포워딩

# 리소스 삭제
kubectl delete -f deployment.yaml
kubectl delete pod <pod-name> --grace-period=0 --force