Reverse Proxy с Nginx: SSL, балансировка и кэширование за 20 минут

# Установка
sudo apt install -y nginx certbot python3-certbot-nginx

# Получение SSL-сертификата
sudo certbot --nginx -d example.com -d www.example.com

# Автообновление (certbot ставит cron автоматически)
sudo certbot renew --dry-run

# /etc/nginx/sites-available/example.com
upstream backend {
    server 127.0.0.1:3000 weight=3;  # основной бэкенд
    server 127.0.0.1:3001 weight=1;  # резервный
    keepalive 32;
}

# Кэш для проксируемых ответов
proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=api_cache:10m
                 max_size=1g inactive=60m;

server {
    listen 443 ssl http2;
    server_name example.com;

    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;

    # Статика
    location /static/ {
        root /var/www;
        expires 30d;
        add_header Cache-Control "public, immutable";
        try_files $uri =404;
    }

    # API с кэшированием
    location /api/ {
        proxy_pass http://backend;
        proxy_cache api_cache;
        proxy_cache_valid 200 5m;
        proxy_cache_bypass $http_cache_control;
        add_header X-Cache-Status $upstream_cache_status;

        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }

    # Всё остальное → бэкенд
    location / {
        proxy_pass http://backend;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
}

server {
    listen 80;
    server_name example.com;
    return 301 https://$server_name$request_uri;
}