The released deb packages had been tested on Ubuntu 18.04 & Debian 9.
It is recommended to initiate a Systemd drop-in file for the haproxy that supports the sdnotify features of systemd, just issue command:
mkdir -p "/etc/systemd/system/haproxy.service.d" && echo -e "[Service]\nRestartSec=6" > "/etc/systemd/system/haproxy.service.d/haproxy.conf"
For the haproxy that DOES NOT support the sdnotify features of systemd, issue command:
mkdir -p "/etc/systemd/system/haproxy.service.d" && echo -e "[Service]\nExecStart=\nExecStart=/usr/local/sbin/haproxy -W -f $CONFIG -p $PIDFILE $EXTRAOPTS\nType=\nType=forking\nRestartSec=6" > "/etc/systemd/system/haproxy.service.d/haproxy.conf"