Recently, nginx 1.9 introduced support for TCP load balancing – similar to what HAProxy is capable of. The one major drawback is that it does not support advanced backend health checks. This is required when running MySQL Galera Cluster, as we’ll explain in the next section. Note that this limitation is removed in the paid-only edition called NGINX Plus.
מקור: nginx as Database Load Balancer for MySQL or MariaDB Galera Cluster | Severalnines