I found: http://serverfault.com/questions/165883/is-there-a-way-to-add-more-backend-server-to-haproxy-without-restarting-haproxy http://sysbible.org/2008/07/26/haproxy-hot-reconfiguration/
However, these options are last documented in version 1.2: http://haproxy.1wt.eu/download/1.2/doc/haproxy-en.txt A brief search did not uncover any similar documentation in newer versions: http://haproxy.1wt.eu/download/1.3/doc/configuration.txt http://haproxy.1wt.eu/download/1.4/doc/configuration.txt What is the current approved way to do hot reconfiguration?