Container

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[ Physical Server (Hardware) ]
           ↓
     [ Host OS (Linux/Windows) ]
           ↓
       [ Hypervisor (KVM, ESXi) ]
         ┌──────────────┬──────────────┐
         │              │              │
  [ Guest OS ]   [ Guest OS ]   [ Guest OS ]
      ↓              ↓              ↓
[ App A ]       [ App B ]       [ App C ]

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[ Physical Server (Hardware) ]
           ↓
     [ Host OS (Linux) ]
           ↓
   [ Container Runtime (Docker, containerd) ]
         ┌──────────────┬──────────────┐
         │              │              │
     [ App A ]      [ App B ]      [ App C ]
    + Lib A        + Lib B        + Lib C

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[Docker Client] <---> [Docker Daemon] <---> [Docker Registry]
                           |
                    [Docker Host]
                           |
        [Images] [Containers] [Networks] [Volumes]

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FROM node:18-alpine
WORKDIR /app
COPY package*.json ./
RUN npm ci --only=production
COPY . .
EXPOSE 3000
CMD ["npm", "start"]

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# 마이크로서비스 컨테이너 구현 예시
# Flask를 사용한 간단한 사용자 서비스 API

from flask import Flask, jsonify, request
import docker
import logging
import time
import os
from concurrent.futures import ThreadPoolExecutor
import requests

# 로깅 설정
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

class ContainerManager:
    """컨테이너 관리 클래스"""
    
    def __init__(self):
        self.client = docker.from_env()
        self.executor = ThreadPoolExecutor(max_workers=10)
    
    def deploy_microservice(self, service_name, image_name, port, env_vars=None):
        """마이크로서비스 컨테이너 배포"""
        try:
            # 기존 컨테이너 정리
            self.cleanup_service(service_name)
            
            # 컨테이너 실행 설정
            container_config = {
                'image': image_name,
                'name': service_name,
                'ports': {f'{port}/tcp': port},
                'detach': True,
                'restart_policy': {'Name': 'unless-stopped'},
                'environment': env_vars or {},
                'labels': {
                    'service.type': 'microservice',
                    'service.name': service_name
                }
            }
            
            # 컨테이너 실행
            container = self.client.containers.run(**container_config)
            logger.info(f"서비스 {service_name} 배포 완료: {container.id}")
            
            # 헬스체크 대기
            self.wait_for_health_check(service_name, port)
            
            return container.id
            
        except Exception as e:
            logger.error(f"서비스 배포 실패 {service_name}: {str(e)}")
            raise
    
    def cleanup_service(self, service_name):
        """기존 서비스 컨테이너 정리"""
        try:
            containers = self.client.containers.list(
                filters={'name': service_name}
            )
            for container in containers:
                container.stop()
                container.remove()
                logger.info(f"기존 컨테이너 정리: {service_name}")
        except Exception as e:
            logger.warning(f"컨테이너 정리 실패: {str(e)}")
    
    def wait_for_health_check(self, service_name, port, timeout=60):
        """서비스 헬스체크 대기"""
        start_time = time.time()
        while time.time() - start_time < timeout:
            try:
                response = requests.get(f'http://localhost:{port}/health')
                if response.status_code == 200:
                    logger.info(f"서비스 {service_name} 헬스체크 성공")
                    return True
            except:
                pass
            time.sleep(2)
        
        raise Exception(f"서비스 {service_name} 헬스체크 실패")
    
    def scale_service(self, service_name, replica_count):
        """서비스 스케일링"""
        try:
            # 현재 실행 중인 서비스 컨테이너 조회
            containers = self.client.containers.list(
                filters={'label': f'service.name={service_name}'}
            )
            
            current_count = len(containers)
            
            if replica_count > current_count:
                # 스케일 아웃
                for i in range(replica_count - current_count):
                    new_name = f"{service_name}-{current_count + i + 1}"
                    # 포트는 동적으로 할당하거나 로드밸런서 사용
                    self.deploy_microservice(new_name, 'user-service:latest', 0)
            
            elif replica_count < current_count:
                # 스케일 인
                excess_containers = containers[replica_count:]
                for container in excess_containers:
                    container.stop()
                    container.remove()
            
            logger.info(f"서비스 {service_name} 스케일링 완료: {replica_count} 복제본")
            
        except Exception as e:
            logger.error(f"스케일링 실패: {str(e)}")
            raise

class UserService:
    """사용자 서비스 구현"""
    
    def __init__(self):
        self.app = Flask(__name__)
        self.users_db = {}  # 실제로는 데이터베이스 사용
        self.setup_routes()
    
    def setup_routes(self):
        """API 라우트 설정"""

		@self.app.route('/health', methods=['GET'])
        def health_check():
            """헬스체크 엔드포인트"""
            return jsonify({
                'status': 'healthy',
                'service': 'user-service',
                'timestamp': time.time()
            })
        
        @self.app.route('/users', methods=['GET'])
        def get_users():
            """사용자 목록 조회"""
            return jsonify({
                'users': list(self.users_db.values()),
                'total': len(self.users_db)
            })
        
        @self.app.route('/users/<user_id>', methods=['GET'])
        def get_user(user_id):
            """특정 사용자 조회"""
            user = self.users_db.get(user_id)
            if user:
                return jsonify(user)
            return jsonify({'error': 'User not found'}), 404
    
        @self.app.route('/users', methods=['POST'])
        def create_user():
            """사용자 생성"""
            data = request.get_json()
            if not data or 'name' not in data:
                return jsonify({'error': 'Name is required'}), 400
            
            user_id = str(len(self.users_db) + 1)
            user = {
                'id': user_id,
                'name': data['name'],
                'email': data.get('email', ''),
                'created_at': time.time()
            }
            
            self.users_db[user_id] = user
            logger.info(f"사용자 생성: {user_id}")
            
            return jsonify(user), 201
        
        @self.app.route('/users/<user_id>', methods=['PUT'])
        def update_user(user_id):
            """사용자 정보 수정"""
            if user_id not in self.users_db:
                return jsonify({'error': 'User not found'}), 404
            
            data = request.get_json()
            user = self.users_db[user_id]
            
            if 'name' in data:
                user['name'] = data['name']
            if 'email' in data:
                user['email'] = data['email']
            
            user['updated_at'] = time.time()
            
            return jsonify(user)
        
        @self.app.route('/users/<user_id>', methods=['DELETE'])
        def delete_user(user_id):
            """사용자 삭제"""
            if user_id not in self.users_db:
                return jsonify({'error': 'User not found'}), 404
            
            del self.users_db[user_id]
            logger.info(f"사용자 삭제: {user_id}")
            
            return jsonify({'message': 'User deleted successfully'})
    
    def run(self, host='0.0.0.0', port=5000, debug=False):
        """서비스 실행"""
        self.app.run(host=host, port=port, debug=debug)

class ServiceOrchestrator:
    """서비스 오케스트레이션 관리"""
    
    def __init__(self):
        self.container_manager = ContainerManager()
        self.services = {}
        self.load_balancer_config = {}
    
    def deploy_microservices_stack(self):
        """마이크로서비스 스택 배포"""
        try:
            # 사용자 서비스 배포
            user_service_id = self.container_manager.deploy_microservice(
                'user-service',
                'user-service:latest',
                5000,
                {'DATABASE_URL': 'postgresql://localhost/users'}
            )
            
            # 주문 서비스 배포
            order_service_id = self.container_manager.deploy_microservice(
                'order-service',
                'order-service:latest',
                5001,
                {'DATABASE_URL': 'postgresql://localhost/orders'}
            )
            
            # 알림 서비스 배포
            notification_service_id = self.container_manager.deploy_microservice(
                'notification-service',
                'notification-service:latest',
                5002,
                {'REDIS_URL': 'redis://localhost:6379'}
            )
            
            # API 게이트웨이 배포
            gateway_id = self.container_manager.deploy_microservice(
                'api-gateway',
                'api-gateway:latest',
                8080,
                {
                    'USER_SERVICE_URL': 'http://user-service:5000',
                    'ORDER_SERVICE_URL': 'http://order-service:5001',
                    'NOTIFICATION_SERVICE_URL': 'http://notification-service:5002'
                }
            )
            
            self.services = {
                'user-service': user_service_id,
                'order-service': order_service_id,
                'notification-service': notification_service_id,
                'api-gateway': gateway_id
            }
            
            logger.info("마이크로서비스 스택 배포 완료")
            return self.services
            
        except Exception as e:
            logger.error(f"스택 배포 실패: {str(e)}")
            self.cleanup_stack()
            raise
    
    def cleanup_stack(self):
        """전체 스택 정리"""
        for service_name in self.services:
            self.container_manager.cleanup_service(service_name)
    
    def monitor_services(self):
        """서비스 모니터링"""
        while True:
            try:
                for service_name in self.services:
                    containers = self.container_manager.client.containers.list(
                        filters={'name': service_name}
                    )
                    
                    if not containers:
                        logger.warning(f"서비스 {service_name} 다운 감지")
                        # 자동 복구 로직
                        self.restart_service(service_name)
                    else:
                        container = containers[0]
                        stats = container.stats(stream=False)
                        
                        # CPU 및 메모리 사용률 계산
                        cpu_usage = self.calculate_cpu_usage(stats)
                        memory_usage = self.calculate_memory_usage(stats)
                        
                        logger.info(f"{service_name} - CPU: {cpu_usage:.2f}%, Memory: {memory_usage:.2f}%")
                        
                        # 자동 스케일링 조건 확인
                        if cpu_usage > 80 or memory_usage > 80:
                            self.auto_scale_service(service_name)
                
                time.sleep(30)  # 30초마다 모니터링
                
            except Exception as e:
                logger.error(f"모니터링 오류: {str(e)}")
                time.sleep(10)
    
    def calculate_cpu_usage(self, stats):
        """CPU 사용률 계산"""
        cpu_delta = stats['cpu_stats']['cpu_usage']['total_usage'] - \
                   stats['precpu_stats']['cpu_usage']['total_usage']
        system_delta = stats['cpu_stats']['system_cpu_usage'] - \
                      stats['precpu_stats']['system_cpu_usage']
        
        if system_delta > 0:
            return (cpu_delta / system_delta) * 100.0
        return 0.0
    
    def calculate_memory_usage(self, stats):
        """메모리 사용률 계산"""
        memory_usage = stats['memory_stats']['usage']
        memory_limit = stats['memory_stats']['limit']
        return (memory_usage / memory_limit) * 100.0
    
    def restart_service(self, service_name):
        """서비스 재시작"""
        logger.info(f"서비스 {service_name} 재시작 중...")
        # 서비스별 설정에 따라 재배포
        # 실제 구현에서는 서비스별 설정을 저장해두고 사용
    
    def auto_scale_service(self, service_name):
        """자동 스케일링"""
        current_replicas = len(self.container_manager.client.containers.list(
            filters={'label': f'service.name={service_name}'}
        ))
        
        if current_replicas < 5:  # 최대 5개 복제본
            new_replicas = min(current_replicas + 1, 5)
            self.container_manager.scale_service(service_name, new_replicas)
            logger.info(f"서비스 {service_name} 자동 스케일링: {new_replicas} 복제본")

# Dockerfile 생성 예시
def create_dockerfile():
    """사용자 서비스용 Dockerfile 생성"""
    dockerfile_content = """
# 멀티스테이지 빌드를 사용한 최적화된 Dockerfile
FROM python:3.9-slim as builder

WORKDIR /app

# 의존성 파일 복사 및 설치
COPY requirements.txt .
RUN pip install --no-cache-dir --user -r requirements.txt

# 프로덕션 단계
FROM python:3.9-slim

# 보안을 위한 비root 사용자 생성
RUN useradd --create-home --shell /bin/bash app

WORKDIR /home/app

# 빌드 단계에서 설치된 패키지 복사
COPY --from=builder /root/.local /home/app/.local

# 애플리케이션 코드 복사
COPY --chown=app:app . .

# 환경변수 설정
ENV PATH=/home/app/.local/bin:$PATH
ENV PYTHONPATH=/home/app
ENV FLASK_APP=user_service.py
ENV FLASK_ENV=production

# 사용자 전환
USER app

# 포트 노출
EXPOSE 5000

# 헬스체크 설정
HEALTHCHECK --interval=30s --timeout=3s --start-period=40s --retries=3 \\
    CMD curl -f http://localhost:5000/health || exit 1

# 애플리케이션 실행
CMD ["python", "-m", "flask", "run", "--host=0.0.0.0", "--port=5000"]
"""
    
    with open('Dockerfile', 'w') as f:
        f.write(dockerfile_content)

# Docker Compose 설정 예시
def create_docker_compose():
    """Docker Compose 파일 생성"""
    compose_content = """
version: '3.8'

services:
  user-service:
    build: ./user-service
    ports:
      - "5000:5000"
    environment:
      - DATABASE_URL=postgresql://postgres:password@db:5432/users
      - REDIS_URL=redis://redis:6379
    depends_on:
      - db
      - redis
    networks:
      - microservices
    deploy:
      replicas: 2
      resources:
        limits:
          cpus: '0.5'
          memory: 512M
        reservations:
          cpus: '0.1'
          memory: 128M
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:5000/health"]
      interval: 30s
      timeout: 10s
      retries: 3

  order-service:
    build: ./order-service
    ports:
      - "5001:5001"
    environment:
      - DATABASE_URL=postgresql://postgres:password@db:5432/orders
      - USER_SERVICE_URL=http://user-service:5000
    depends_on:
      - db
      - user-service
    networks:
      - microservices

  api-gateway:
    build: ./api-gateway
    ports:
      - "8080:8080"
    environment:
      - USER_SERVICE_URL=http://user-service:5000
      - ORDER_SERVICE_URL=http://order-service:5001
    depends_on:
      - user-service
      - order-service
    networks:
      - microservices

  db:
    image: postgres:13
    environment:
      - POSTGRES_DB=microservices
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=password
    volumes:
      - postgres_data:/var/lib/postgresql/data
    networks:
      - microservices

  redis:
    image: redis:6-alpine
    networks:
      - microservices

  prometheus:
    image: prom/prometheus
    ports:
      - "9090:9090"
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml
    networks:
      - microservices

  grafana:
    image: grafana/grafana
    ports:
      - "3000:3000"
    environment:
      - GF_SECURITY_ADMIN_PASSWORD=admin
    networks:
      - microservices

volumes:
  postgres_data:

networks:
  microservices:
    driver: bridge
"""
    
    with open('docker-compose.yml', 'w') as f:
        f.write(compose_content)

# 사용 예시
if __name__ == "__main__":
    # 개발 환경에서 서비스 실행
    if os.getenv('DEVELOPMENT') == 'true':
        user_service = UserService()
        user_service.run(debug=True)
    
    # 프로덕션 환경에서 오케스트레이션
    else:
        orchestrator = ServiceOrchestrator()
        orchestrator.deploy_microservices_stack()
        
        # 백그라운드에서 모니터링 시작
        import threading
        monitor_thread = threading.Thread(target=orchestrator.monitor_services)
        monitor_thread.daemon = True
        monitor_thread.start()
        
        logger.info("컨테이너 오케스트레이션 시스템 시작됨")
        
        # 메인 스레드 유지
        try:
            while True:
                time.sleep(1)
        except KeyboardInterrupt:
            logger.info("시스템 종료 중...")
            orchestrator.cleanup_stack()

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# Docker SDK를 이용한 컨테이너 실행 예시
import docker
client = docker.from_env()
container = client.containers.run('nginx', detach=True, ports={'80/tcp': 8080})
print(f'컨테이너 ID: {container.id}')

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import subprocess

def build_and_push(image_tag):
    subprocess.run(["docker", "build", "-t", image_tag, "."], check=True)
    subprocess.run(["docker", "push", image_tag], check=True)

def deploy_to_k8s(deployment_file):
    subprocess.run(["kubectl", "apply", "-f", deployment_file], check=True)

if __name__ == "__main__":
    tag = "registry.example.com/myapp:latest"
    build_and_push(tag)
    deploy_to_k8s("k8s/deployment.yaml")
    print("✅ CI/CD 파이프라인 이미지 빌드 및 배포 완료")

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docker buildx create --use
docker buildx build --platform linux/amd64,linux/arm64 \
  -t myrepo/app:latest --push .

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# .github/workflows/docker-build.yaml
name: Docker Build and Push

on:
  push:
    branches: [main]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v3
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v2
      - name: Login to Docker Hub
        uses: docker/login-action@v2
        with:
          username: ${{ secrets.DOCKER_USER }}
          password: ${{ secrets.DOCKER_PASS }}
      - name: Build and Push
        uses: docker/build-push-action@v5
        with:
          context: .
          push: true
          platforms: linux/amd64,linux/arm64
          tags: myrepo/app:latest

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docker-build:
  image: docker:latest
  services:
    - docker:dind
  script:
    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
    - docker buildx create --use
    - docker buildx build --platform linux/amd64,linux/arm64 -t $CI_REGISTRY_IMAGE:latest --push .