timedatex replacing systemd-timedated for NTP packages

Tomasz Torcz tomek at pipebreaker.pl
Thu Nov 27 22:08:45 UTC 2014

On Thu, Nov 27, 2014 at 10:53:45PM +0100, Tom Gundersen wrote:
> On Thu, Nov 27, 2014 at 10:00 PM, Andrew Lutomirski <luto at mit.edu> wrote:
> > On Thu, Nov 27, 2014 at 12:51 PM, Tom Gundersen <teg at jklm.no> wrote:
> >> On Wed, Nov 26, 2014 at 3:10 PM, Chris Adams <linux at cmadams.net> wrote:
> >>> Once upon a time, Tomasz Torcz <tomek at pipebreaker.pl> said:
> >>>> On Wed, Nov 26, 2014 at 08:01:37AM -0600, Chris Adams wrote:
> >>>> > Once upon a time, Florian Weimer <fweimer at redhat.com> said:
> >>>> > > Do we even use the DHCP NTP server assignment?
> >>>> >
> >>>> > I believe it is used for chrony and ntpd, don't know about sysmted's new
> >>>> > implementation.
> >>>>
> >>>>   systemd-timesyncd uses DHCP-provided NTP servers only if systemd-networkd
> >>>> is used as DHCP client.
> >>>
> >> There are technical reasons for this choice, not merely NIH.
> >
> > And those technical reasons are?
> >
> > I realize that the shell-script-fu that most DHCP clients seem to
> > require is a bit messy, but it does work, and it should be more than
> > flexible enough to plug in some systemd-timesyncd controls.
> networkd allows consumers of network information (such as NTP servers,
> DNS resolvers, HTTP proxy brokers,...) to subscribe to this
> information (currently only via a C API [0], but could just as well
> have been dbus) and be notified of changes to it. Other DHCP clients
> will typically instead call a bunch of hooks (with env vars set) on
> every configuration change (and it is then presumably the job of the
> hook to instruct the NTP client, or whatever else, to change its
> config).

  Nb. chronyd's unit in Fedora has:
ExecStartPost=/usr/libexec/chrony-helper add-dhclient-servers

  This is a script which gets NTP servers names from dhclient and
feeds them to chronyd.  Nothing prevents extending this script
to get data from networkd, too.

  (sorry about slight offtopic).

Tomasz Torcz               "Never underestimate the bandwidth of a station
xmpp: zdzichubg at chrome.pl    wagon filled with backup tapes." -- Jim Gray

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