게이트웨이

# 로컬 시스템 게이트웨이 확인
# Linux/macOS
ip route | grep default        # default via 192.168.1.1 dev eth0
netstat -rn | grep default     # 라우팅 테이블 전체

# Windows
route print | findstr "0.0.0.0"
ipconfig | findstr "게이트웨이"

# AWS CLI: Internet Gateway 생성
aws ec2 create-internet-gateway \
    --tag-specifications 'ResourceType=internet-gateway,Tags=[{Key=Name,Value=prod-igw}]'

# VPC에 IGW 연결
aws ec2 attach-internet-gateway \
    --internet-gateway-id igw-12345678 \
    --vpc-id vpc-12345678

# NAT Gateway 생성 (Elastic IP 필요)
aws ec2 allocate-address --domain vpc  # EIP 할당
aws ec2 create-nat-gateway \
    --subnet-id subnet-public-12345 \
    --allocation-id eipalloc-12345678 \
    --tag-specifications 'ResourceType=natgateway,Tags=[{Key=Name,Value=prod-nat}]'

# NAT Gateway 상태 확인 (available까지 2-3분 소요)
aws ec2 describe-nat-gateways \
    --nat-gateway-ids nat-12345678 \
    --query 'NatGateways[0].State'

# 프라이빗 서브넷 라우팅 테이블에 NAT Gateway 경로 추가
aws ec2 create-route \
    --route-table-id rtb-private-12345 \
    --destination-cidr-block 0.0.0.0/0 \
    --nat-gateway-id nat-12345678

# Transit Gateway (여러 VPC 연결)
aws ec2 create-transit-gateway \
    --description "Multi-VPC Hub" \
    --options "AutoAcceptSharedAttachments=enable"

// Express.js API Gateway 패턴 구현
const express = require('express');
const { createProxyMiddleware } = require('http-proxy-middleware');
const rateLimit = require('express-rate-limit');
const jwt = require('jsonwebtoken');

const app = express();

// Rate Limiting (분당 100 요청)
const limiter = rateLimit({
    windowMs: 60 * 1000,
    max: 100,
    message: { error: 'Too many requests, please try again later' }
});
app.use(limiter);

// JWT 인증 미들웨어
const authMiddleware = (req, res, next) => {
    const token = req.headers.authorization?.split(' ')[1];
    if (!token) return res.status(401).json({ error: 'No token provided' });

    try {
        req.user = jwt.verify(token, process.env.JWT_SECRET);
        next();
    } catch (err) {
        res.status(403).json({ error: 'Invalid token' });
    }
};

// 마이크로서비스 라우팅
const services = {
    users: 'http://user-service:3001',
    orders: 'http://order-service:3002',
    products: 'http://product-service:3003'
};

// 각 서비스로 프록시
Object.entries(services).forEach(([path, target]) => {
    app.use(`/api/${path}`, authMiddleware, createProxyMiddleware({
        target,
        changeOrigin: true,
        pathRewrite: { [`^/api/${path}`]: '' },
        onProxyReq: (proxyReq, req) => {
            // 사용자 정보를 헤더에 추가
            proxyReq.setHeader('X-User-Id', req.user.id);
            proxyReq.setHeader('X-Request-Id', crypto.randomUUID());
        },
        onError: (err, req, res) => {
            console.error(`Proxy error: ${err.message}`);
            res.status(502).json({ error: 'Service unavailable' });
        }
    }));
});

// Health Check
app.get('/health', (req, res) => res.json({ status: 'ok' }));

app.listen(3000, () => console.log('API Gateway running on :3000'));