PREIN

/bin/sh

getent group haproxy >/dev/null || \
    groupadd -r haproxy
getent passwd haproxy >/dev/null || \
    useradd -r -g haproxy -d /var/lib/haproxy \
    -s /sbin/nologin -c "haproxy" haproxy
exit 0

PREUN

/bin/sh

if [ $1 -eq 0 ] ; then 
        # Package removal, not upgrade 
        systemctl --no-reload disable haproxy.service > /dev/null 2>&1 || : 
        systemctl stop haproxy.service > /dev/null 2>&1 || : 
fi

POSTIN

/bin/sh

if [ $1 -eq 1 ] ; then 
        # Initial installation 
        systemctl preset haproxy.service >/dev/null 2>&1 || : 
fi

POSTUN

/bin/sh

systemctl daemon-reload >/dev/null 2>&1 || : 
if [ $1 -ge 1 ] ; then 
        # Package upgrade, not uninstall 
        systemctl try-restart haproxy.service >/dev/null 2>&1 || : 
fi