리버스 프록시

# /etc/haproxy/haproxy.cfg - 고성능 로드밸런서

global
    maxconn 50000
    log /dev/log local0
    chroot /var/lib/haproxy
    stats socket /run/haproxy/admin.sock mode 660 level admin

defaults
    mode http
    timeout connect 5s
    timeout client  30s
    timeout server  30s
    option httplog
    option dontlognull
    option forwardfor

# 프론트엔드 (리버스 프록시 진입점)
frontend http_front
    bind *:80
    bind *:443 ssl crt /etc/ssl/certs/example.pem

    # HTTP → HTTPS 리다이렉트
    http-request redirect scheme https unless { ssl_fc }

    # ACL 기반 라우팅
    acl is_api path_beg /api/
    acl is_static path_beg /static/

    use_backend api_servers if is_api
    use_backend static_servers if is_static
    default_backend web_servers

# 백엔드 서버 그룹
backend api_servers
    balance roundrobin
    option httpchk GET /health
    http-check expect status 200

    server api1 10.0.0.1:8080 check weight 100
    server api2 10.0.0.2:8080 check weight 100
    server api3 10.0.0.3:8080 check weight 50 backup

backend web_servers
    balance leastconn
    cookie SERVERID insert indirect nocache

    server web1 10.0.1.1:3000 check cookie web1
    server web2 10.0.1.2:3000 check cookie web2

backend static_servers
    balance uri
    server cdn1 10.0.2.1:80 check
    server cdn2 10.0.2.2:80 check

# 통계 대시보드
listen stats
    bind *:8404
    stats enable
    stats uri /stats
    stats auth admin:password123

// Node.js 리버스 프록시 (http-proxy-middleware)
const express = require('express');
const { createProxyMiddleware } = require('http-proxy-middleware');

const app = express();

// 로깅 미들웨어
app.use((req, res, next) => {
    console.log(`[${new Date().toISOString()}] ${req.method} ${req.url}`);
    next();
});

// API 서버로 프록시 (로드밸런싱)
const apiServers = ['http://10.0.0.1:8080', 'http://10.0.0.2:8080'];
let currentServer = 0;

app.use('/api', createProxyMiddleware({
    router: (req) => {
        // Round-robin 로드밸런싱
        const target = apiServers[currentServer];
        currentServer = (currentServer + 1) % apiServers.length;
        return target;
    },
    changeOrigin: true,
    pathRewrite: { '^/api': '' },

    // 요청/응답 수정
    onProxyReq: (proxyReq, req, res) => {
        proxyReq.setHeader('X-Real-IP', req.ip);
        proxyReq.setHeader('X-Forwarded-For', req.ip);
    },

    onProxyRes: (proxyRes, req, res) => {
        // 보안 헤더 추가
        proxyRes.headers['X-Frame-Options'] = 'SAMEORIGIN';
        proxyRes.headers['X-Content-Type-Options'] = 'nosniff';
    },

    onError: (err, req, res) => {
        console.error('Proxy error:', err);
        res.status(502).json({ error: 'Bad Gateway' });
    }
}));

// WebSocket 프록시
app.use('/ws', createProxyMiddleware({
    target: 'ws://10.0.0.1:8080',
    ws: true,
    changeOrigin: true
}));

// 정적 파일 서버로 프록시 (캐싱)
app.use('/static', createProxyMiddleware({
    target: 'http://cdn.example.com',
    changeOrigin: true,
    selfHandleResponse: false
}));

app.listen(80, () => {
    console.log('Reverse proxy running on port 80');
});