timesyncd: beef up NTP server selection logic, and acquire NTP servers from DHCP

2 files changed, 127 insertions, 0 deletions

diff --git a/man/systemd-timesyncd.service.xml b/man/systemd-timesyncd.service.xml
index 9647c54ddd..47e243c271 100644
--- a/man/systemd-timesyncd.service.xml
+++ b/man/systemd-timesyncd.service.xml
@@ -65,12 +65,24 @@
                 subsequent reboots to ensure it
                 monotonically advances even if the system lacks a
                 battery-buffered RTC chip.</para>
+
+                <para>The NTP servers contacted are determined from
+                the global settings in
+                <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                the per-link static settings in
+                <filename>.network</filename> files, and the per-link
+                dynamic settings received over DHCP. See
+                <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+                for more details.</para>
         </refsect1>
 
         <refsect1>
                 <title>See Also</title>
                 <para>
                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>localtime</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                         <citerefentry project='man-pages'><refentrytitle>hwclock</refentrytitle><manvolnum>8</manvolnum></citerefentry>
diff --git a/man/timesyncd.conf.xml b/man/timesyncd.conf.xml
new file mode 100644
index 0000000000..aeb7182f91
--- /dev/null
+++ b/man/timesyncd.conf.xml
@@ -0,0 +1,115 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+  This file is part of systemd.
+
+  Copyright 2014 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="timesyncd.conf" conditional='ENABLE_TIMESYNCD'>
+        <refentryinfo>
+                <title>timesyncd.conf</title>
+                <productname>systemd</productname>
+
+                <authorgroup>
+                        <author>
+                                <contrib>Developer</contrib>
+                                <firstname>Lennart</firstname>
+                                <surname>Poettering</surname>
+                                <email>lennart@poettering.net</email>
+                        </author>
+                </authorgroup>
+        </refentryinfo>
+
+        <refmeta>
+                <refentrytitle>timesyncd.conf</refentrytitle>
+                <manvolnum>5</manvolnum>
+        </refmeta>
+
+        <refnamediv>
+                <refname>timesyncd.conf</refname>
+                <refpurpose>Network Time Synchronization configuration file</refpurpose>
+        </refnamediv>
+
+        <refsynopsisdiv>
+                <para><filename>/etc/systemd/timesyncd.conf</filename></para>
+        </refsynopsisdiv>
+
+        <refsect1>
+                <title>Description</title>
+
+                <para>When starting, systemd-timesyncd will read the
+                configuration file
+                <filename>timesyncd.conf</filename>.  This
+                configuration file controls NTP network time
+                synchronization.</para>
+
+        </refsect1>
+
+        <refsect1>
+                <title>Options</title>
+
+                <variablelist class='network-directives'>
+
+                        <varlistentry>
+                                <term><varname>NTP=</varname></term>
+                                <listitem><para>A space separated list
+                                of NTP servers host names or IP
+                                addresses. During runtime this list is
+                                combined with any per-interface NTP
+                                servers acquired from
+                                <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. systemd-timesyncd
+                                will contact all configured system or
+                                per-interface servers in turn until
+                                one is found that responds. This
+                                setting defaults to the empty
+                                list.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>FallbackNTP=</varname></term>
+                                <listitem><para>A space separated list
+                                of NTP server host names or IP
+                                addresses to be used as the fallback
+                                NTP servers. Any per-interface NTP
+                                servers obtained from
+                                <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+                                take precedence over this setting, as
+                                do any servers set via
+                                <varname>NTP=</varname> above. This
+                                setting is hence only used if no other
+                                NTP server information is known. If
+                                this option is not given, a
+                                compiled-in list of NTP servers is
+                                used instead.</para></listitem>
+                        </varlistentry>
+
+                </variablelist>
+        </refsect1>
+
+        <refsect1>
+                  <title>See Also</title>
+                  <para>
+                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+                  </para>
+        </refsect1>
+
+</refentry>