http {
    # Map remote IPs to labels
    map $remote_addr $client_label {
        default "Unknown";   # fallback if IP doesn't match
        192.168.1.10   "A";
        192.168.1.11   "B";
        203.0.113.25   "C";
    }

    upstream backend {
        server 127.0.0.1:8080;
    }

    server {
        listen 80;

        location / {
            proxy_pass http://backend;

            # Send the mapped label as a header to backend
            proxy_set_header X-Client-Label $client_label;
        }
    }
}
