Instead of parsing the kernel command line to find the destination(s)
where syslog messages should be forwarded, we can use a *dhcpcd* hook to
get them from the DHCP lease.
By default, *dhcpcd* generates a "complete" `chrony.conf` file using the
NTP servers specified in the DHCP lease, and then restarts the Chrony
daemon. This is unnecessary, as *chrony* can reload its list of
sources without restarting, and also problematic in our case. For one
thing, *dhcpcd* tries to write to `/etc/chrony.conf` directly, which is
obviously impossible when the root filesystem is immutable.
Fortunately, it is flexible enough to be configured to leave
`/etc/chrony.conf` alone and generate a different file and then tell
*chrony* to reread it.
The *chrony-wait.service* unit introduces a delay into the system
startup that allows follow-up units to wait until the system time is
confirmed correct. The unit file itself was derived from the one
included in the *chrony* package for Fedora.
Instead of manually managing symlinks to enable units, we can define a
system preset that lists which units we want disabled. Units that have
in `Install` section are automatically enabled.
Dustin