nginx.conf

events {
    worker_connections 1024;
}

http {
    # Security: hide nginx version
    server_tokens off;

    # Request limits
    client_max_body_size 50m;
    client_body_timeout 30s;
    client_header_timeout 30s;

    upstream certmate {
        # If you change the certmate container PORT env var, update this port too.
        server certmate:8000 max_fails=3 fail_timeout=30s;
        keepalive 32;
    }

    server {
        listen 80;
        server_name _;

        # Redirect all HTTP to HTTPS when SSL is configured
        location / {
            return 301 https://$host$request_uri;
        }

        # Allow health checks over HTTP (for Docker healthcheck)
        location /health {
            proxy_pass http://certmate;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
        }
    }

    # HTTPS configuration (optional)
    server {
        listen 443 ssl;
        server_name _;

        ssl_certificate /etc/nginx/ssl/cert.pem;
        ssl_certificate_key /etc/nginx/ssl/key.pem;

        # TLS hardening
        ssl_protocols TLSv1.2 TLSv1.3;
        ssl_ciphers 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384';
        ssl_prefer_server_ciphers on;
        ssl_session_timeout 1d;
        ssl_session_cache shared:SSL:10m;
        ssl_session_tickets off;

        # Security headers (defense in depth — duplicated from Flask for proxy-level protection)
        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 Permissions-Policy "camera=(), microphone=(), geolocation=(), payment=()" always;
        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;

        location / {
            proxy_pass http://certmate;
            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;

            # Proxy timeouts
            proxy_connect_timeout 60s;
            proxy_send_timeout 60s;
            proxy_read_timeout 60s;

            # Keepalive to upstream
            proxy_http_version 1.1;
            proxy_set_header Connection "";
        }
    }
}