gentoo-overlay/sys-auth/sssd/files/sssd.service

[Unit]
Description=System Security Services Daemon
# SSSD will not be started until syslog is
After=syslog.target

[Service]
ExecStart=/usr/sbin/sssd -D -f
# These two should be used with traditional UNIX forking daemons
# consult systemd.service(5) for more details
Type=forking
PIDFile=/run/sssd.pid

[Install]
WantedBy=multi-user.target