This is based on the work done by Lang Pavel. His work is available at https://github.com/langpavel/haproxy-doc. His PDF document for 1.5 was a little bit outdated. I took decision to regenate this document for HAProxy 1.5.14.

Document is available at http://www.davidgis.fr/documentation/HAProxy/1.5.14/HAProxy-1.5.14_configuration.pdf