# Ubuntu / Debian
sudo apt update
sudo apt install nginx
sudo systemctl enable nginx
sudo systemctl start nginx

# Verify
nginx -v
curl http://localhost

server {
    listen 80;
    server_name myapp.example.com;

    location / {
        proxy_pass http://127.0.0.1:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        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;
    }
}

# Install Certbot
sudo apt install certbot python3-certbot-nginx

# Obtain certificate
sudo certbot --nginx -d myapp.example.com

# Auto-renewal is set up by default; verify with:
sudo certbot renew --dry-run

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

    ssl_certificate /etc/letsencrypt/live/myapp.example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/myapp.example.com/privkey.pem;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers HIGH:!aNULL:!MD5;

    location / {
        proxy_pass http://127.0.0.1:3000;
        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;
    }
}

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

upstream backend {
    least_conn;
    server 10.0.1.10:3000;
    server 10.0.1.11:3000;
    server 10.0.1.12:3000;
}

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

    location / {
        proxy_pass http://backend;
    }
}

proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=app_cache:10m max_size=1g inactive=60m;

server {
    location / {
        proxy_pass http://backend;
        proxy_cache app_cache;
        proxy_cache_valid 200 10m;
        proxy_cache_valid 404 1m;
        add_header X-Cache-Status $upstream_cache_status;
    }

    location /api/ {
        proxy_pass http://backend;
        proxy_cache off;
    }
}

limit_req_zone $binary_remote_addr zone=api_limit:10m rate=10r/s;

server {
    location /api/ {
        limit_req zone=api_limit burst=20 nodelay;
        proxy_pass http://backend;
    }
}

add_header X-Frame-Options "SAMEORIGIN" always;
add_header X-Content-Type-Options "nosniff" always;
add_header X-XSS-Protection "1; mode=block" always;
add_header Referrer-Policy "strict-origin-when-cross-origin" always;
add_header Content-Security-Policy "default-src 'self'" always;
add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;

nginx -t                    # Test configuration
sudo nginx -s reload        # Reload without downtime
sudo tail -f /var/log/nginx/error.log
sudo tail -f /var/log/nginx/access.log