timedated: add back support for ntp-units.d/

We removed support for foreign services (and ntp-units.d/) in b72ddf0f4.
Support for foreign services was added back in 5d280742, but through an
environment variable.

The problem with the env var approach is that it only works as a mechanism
to select one item, and doesn't work nicely as a mechinism to create a list
of items through drop-ins (because the env var can be easily overridden, but not
extended). Having a list of "ntp providers" is important to be able to reliably disable
all of them when that is requested.

Another problem is that nobody ever bothered to care about our new "standard".
ntp-units.d/ is a nice simple format that works and is already supported by
chrony and ntpd and timedatex. If we were to introduce and ask people to follow
a new standard, there should be some good reason for this. The idea with env
vars has lower functionality, requires systemd-specific syntax. We should just
re-adopt the format that we originally introduced and that seems to work for
everyone, and more on to more interesting problems.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2019-07-21 15:06:35 +02:00
parent 670fb0b483
commit afaae43bb1
4 changed files with 111 additions and 40 deletions

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@ -31,7 +31,7 @@
<para><filename>systemd-timedated</filename> is a system service
that may be used as a mechanism to change the system clock and
timezone, as well as to enable/disable NTP time synchronization.
timezone, as well as to enable/disable network time synchronization.
<filename>systemd-timedated</filename> is automatically activated
on request and terminates itself when it is unused.</para>
@ -46,25 +46,36 @@
</refsect1>
<refsect1>
<title>Environment</title>
<title>List of network time synchronization services</title>
<variablelist class='environment-variables'>
<varlistentry>
<term><varname>$SYSTEMD_TIMEDATED_NTP_SERVICES</varname></term>
<para><command>systemd-timesyncd</command> will look for files with a <literal>.list</literal> extension
in <filename>ntp-units.d/</filename> directories. Each file is parsed as a list of unit names, one per
line. Empty lines and lines with comments (<literal>#</literal>) are ignored. Files are read from
<filename>/usr/lib/systemd/ntp-units.d/</filename> and the corresponding directories under
<filename>/etc/</filename>, <filename>/run/</filename>, <filename>/usr/local/lib/</filename>. Files in
<filename>/etc/</filename> override files with the same name in <filename>/run/</filename>,
<filename>/usr/local/lib/</filename>, and <filename>/usr/lib/</filename>. Files in
<filename>/run/</filename> override files with the same name under <filename>/usr/</filename>. Packages
should install their configuration files in <filename>/usr/lib/</filename> (distribution packages) or
<filename>/usr/local/lib/</filename> (local installs).</para>
<listitem><para>Colon-separated list of unit names of NTP client services.
If not set, then
<citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
is used. See the entries of NTP related commands of
<citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
for details about this.</para>
<example>
<title><filename>ntp-units.d/</filename> entry for <command>systemd-timesyncd</command></title>
<programlisting># /usr/lib/systemd/ntp-units.d/80-systemd-timesync.list
systemd-timesyncd.service
</programlisting>
</example>
<para>Example:
<programlisting>SYSTEMD_TIMEDATED_NTP_SERVICES=ntpd.service:chronyd.service:systemd-timesyncd.service</programlisting>
</para></listitem>
</varlistentry>
</variablelist>
<para>If the environment variable <varname>$SYSTEMD_TIMEDATED_NTP_SERVICES</varname> is set,
<command>systemd-timesyncd</command> will parse the contents of that variable as a colon-separated list
of unit names. When set, this variable overrides the file-based list described above.</para>
<example>
<title>An override that specifies that <command>chronyd</command> should be used if available</title>
<programlisting>SYSTEMD_TIMEDATED_NTP_SERVICES=chronyd.service:systemd-timesyncd.service</programlisting>
</example>
</refsect1>
<refsect1>
<title>See Also</title>
<para>

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@ -23,22 +23,25 @@
<refsynopsisdiv>
<cmdsynopsis>
<command>timedatectl <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg></command>
<command>timedatectl</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="req">COMMAND</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>timedatectl</command> may be used to query and
change the system clock and its settings.</para>
<para><command>timedatectl</command> may be used to query and change the system clock and its settings,
and enable or disable time synchronization services.</para>
<para>Use
<citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
to initialize the system time zone for mounted (but not booted)
system images.</para>
<para><command>timedatectl</command> may be used to show the current status of
<para><command>timedatectl</command> may be used to show the current status of time synchronization
services, for example
<citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
@ -123,11 +126,8 @@
<varlistentry>
<term><command>status</command></term>
<listitem><para>Show current settings of the system clock and RTC,
including whether network time synchronization through
<filename>systemd-timesyncd.service</filename> is active. Even if it is
inactive, a different service might still synchronize the clock.
If no command is specified, this is the implied default.
<listitem><para>Show current settings of the system clock and RTC, including whether network time
synchronization is active. If no command is specified, this is the implied default.
</para></listitem>
</varlistentry>
@ -193,11 +193,11 @@
<varlistentry>
<term><command>set-ntp [BOOL]</command></term>
<listitem><para>Takes a boolean argument. Controls whether network time synchronization is active
and enabled (if available). If the argument is true, this enables and starts the first existed
service listed in the environment variable <varname>$SYSTEMD_TIMEDATED_NTP_SERVICES</varname>
of <filename>systemd-timedated.service</filename>. If the argument is false, then this disables and
stops the all services listed in <varname>$SYSTEMD_TIMEDATED_NTP_SERVICES</varname>.</para></listitem>
<listitem><para>Takes a boolean argument. Controls whether network time synchronization is active and
enabled (if available). If the argument is true, this enables and starts the first existing network
synchronization service. If the argument is false, then this disables and stops the known network
synchronization services. The way that the list of services is built is described below.</para>
</listitem>
</varlistentry>
</variablelist>
@ -250,8 +250,7 @@
<refsect1>
<title>Exit status</title>
<para>On success, 0 is returned, a non-zero failure
code otherwise.</para>
<para>On success, 0 is returned, a non-zero failure code otherwise.</para>
</refsect1>
<xi:include href="less-variables.xml" />

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@ -247,6 +247,11 @@ static int guess_type(const char **name, bool *is_usr, bool *is_collection, cons
if (path_equal(n, "kernel/install.d"))
ext = ".install";
if (path_equal(n, "systemd/ntp-units.d")) {
coll = true;
ext = ".list";
}
if (PATH_IN_SET(n, "systemd/system-preset", "systemd/user-preset")) {
coll = true;
ext = ".preset";

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@ -15,7 +15,9 @@
#include "bus-error.h"
#include "bus-util.h"
#include "clock-util.h"
#include "conf-files.h"
#include "def.h"
#include "fd-util.h"
#include "fileio-label.h"
#include "fileio.h"
#include "fs-util.h"
@ -36,6 +38,8 @@
#define NULL_ADJTIME_UTC "0.0 0 0\n0\nUTC\n"
#define NULL_ADJTIME_LOCAL "0.0 0 0\n0\nLOCAL\n"
#define UNIT_LIST_DIRS (const char* const*) CONF_PATHS_STRV("systemd/ntp-units.d")
typedef struct UnitStatusInfo {
char *name;
char *load_state;
@ -117,20 +121,17 @@ static int context_add_ntp_service(Context *c, const char *s) {
return 0;
}
static int context_parse_ntp_services(Context *c) {
static int context_parse_ntp_services_from_environment(Context *c) {
const char *env, *p;
int r;
assert(c);
env = getenv("SYSTEMD_TIMEDATED_NTP_SERVICES");
if (!env) {
r = context_add_ntp_service(c, "systemd-timesyncd.service");
if (r < 0)
log_warning_errno(r, "Failed to add NTP service \"systemd-timesyncd.service\", ignoring: %m");
if (!env)
return 0;
}
log_debug("Using list of ntp services from environment variable $SYSTEMD_TIMEDATED_NTP_SERVICES.");
for (p = env;;) {
_cleanup_free_ char *word = NULL;
@ -150,7 +151,62 @@ static int context_parse_ntp_services(Context *c) {
log_warning_errno(r, "Failed to add NTP service \"%s\", ignoring: %m", word);
}
return 0;
return 1;
}
static int context_parse_ntp_services_from_disk(Context *c) {
_cleanup_strv_free_ char **files = NULL;
char **f;
int r;
r = conf_files_list_strv(&files, ".list", NULL, CONF_FILES_FILTER_MASKED, UNIT_LIST_DIRS);
if (r < 0)
return log_error_errno(r, "Failed to enumerate .list files: %m");
STRV_FOREACH(f, files) {
_cleanup_fclose_ FILE *file = NULL;
log_debug("Reading file '%s'", *f);
r = fopen_unlocked(*f, "re", &file);
if (r < 0) {
log_error_errno(r, "Failed to open %s, ignoring: %m", *f);
continue;
}
for (;;) {
_cleanup_free_ char *line = NULL;
const char *word;
r = read_line(file, LINE_MAX, &line);
if (r < 0) {
log_error_errno(r, "Failed to read %s, ignoring: %m", *f);
continue;
}
if (r == 0)
break;
word = strstrip(line);
if (isempty(word) || startswith("#", word))
continue;
r = context_add_ntp_service(c, word);
if (r < 0)
log_warning_errno(r, "Failed to add NTP service \"%s\", ignoring: %m", word);
}
}
return 1;
}
static int context_parse_ntp_services(Context *c) {
int r;
r = context_parse_ntp_services_from_environment(c);
if (r != 0)
return r;
return context_parse_ntp_services_from_disk(c);
}
static int context_ntp_service_is_active(Context *c) {