Linux Babe published a tutorial about running Apache, Nginx, and HAProxy on same server.

Run Apache, Nginx & HAProxy on Same Server (Debian, Ubuntu, CentOS)

Make Apache and Nginx use port 80, 443 at the same time, on the same server. Run Apache, Nginx & HAProxy on Same Server (Debian, Ubuntu, CentOS)

Run Apache, Nginx & HAProxy on Same Server (Debian, Ubuntu, CentOS)