[Unit]
Description=Wait for chrony to synchronize system clock
Documentation=man:chronyc(1)
After=chronyd.service
Requires=chronyd.service
Before=time-sync.target
Wants=time-sync.target

[Service]
Type=oneshot
# Wait for chronyd to update the clock and the remaining
# correction to be less than 0.1 seconds
ExecStart=/usr/bin/chronyc -h 127.0.0.1,::1 waitsync 0 0.1 0.0 1
# Wait for at most 3 minutes
TimeoutStartSec=180
RemainAfterExit=yes
StandardOutput=null

[Install]
WantedBy=multi-user.target