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From 2b5c9fceaaa30ec9c2d031c9ca32b71c43f22f98 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 3 Jan 2023 12:55:50 +0100
Subject: [PATCH] notify: add --stopping + --reloading switches
These wrap RELOADING=1 and STOPPING=1 messages. The former is
particularly useful, since we want to insert the MONOTONIC_USEC= field
into the message automatically, which is easy from C but harder from
shell.
(cherry picked from commit fd0f4da5457fbf7136f2d1888142d5fea75fd45a)
Related: RHEL-6090
---
man/systemd-notify.xml | 107 ++++++++++++++++++++++++-----------------
src/notify/notify.c | 39 +++++++++++++--
2 files changed, 97 insertions(+), 49 deletions(-)
diff --git a/man/systemd-notify.xml b/man/systemd-notify.xml
index 1327d23155..a275123d40 100644
--- a/man/systemd-notify.xml
+++ b/man/systemd-notify.xml
@@ -30,34 +30,35 @@
<refsect1>
<title>Description</title>
- <para><command>systemd-notify</command> may be called by daemon
- scripts to notify the init system about status changes. It can be
- used to send arbitrary information, encoded in an
- environment-block-like list of strings. Most importantly, it can be
- used for start-up completion notification.</para>
-
- <para>This is mostly just a wrapper around
- <function>sd_notify()</function> and makes this functionality
+ <para><command>systemd-notify</command> may be called by service scripts to notify the invoking service
+ manager about status changes. It can be used to send arbitrary information, encoded in an
+ environment-block-like list of strings. Most importantly, it can be used for start-up completion
+ notification.</para>
+
+ <para>This is mostly just a wrapper around <function>sd_notify()</function> and makes this functionality
available to shell scripts. For details see
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
- <para>The command line may carry a list of environment variables
- to send as part of the status update.</para>
+ <para>The command line may carry a list of environment variables to send as part of the status
+ update.</para>
<para>Note that systemd will refuse reception of status updates from this command unless
<varname>NotifyAccess=</varname> is set for the service unit this command is called from.</para>
- <para>Note that <function>sd_notify()</function> notifications may be attributed to units correctly only if either
- the sending process is still around at the time PID 1 processes the message, or if the sending process is
- explicitly runtime-tracked by the service manager. The latter is the case if the service manager originally forked
- off the process, i.e. on all processes that match <varname>NotifyAccess=</varname><option>main</option> or
- <varname>NotifyAccess=</varname><option>exec</option>. Conversely, if an auxiliary process of the unit sends an
- <function>sd_notify()</function> message and immediately exits, the service manager might not be able to properly
- attribute the message to the unit, and thus will ignore it, even if <varname>NotifyAccess=</varname><option>all
- </option> is set for it. When <option>--no-block</option> is used, all synchronization for reception of notifications
- is disabled, and hence the aforementioned race may occur if the invoking process is not the service manager or spawned
- by the service manager.</para>
+ <para>Note that <function>sd_notify()</function> notifications may be attributed to units correctly only
+ if either the sending process is still around at the time the service manager processes the message, or
+ if the sending process is explicitly runtime-tracked by the service manager. The latter is the case if
+ the service manager originally forked off the process, i.e. on all processes that match
+ <varname>NotifyAccess=</varname><option>main</option> or
+ <varname>NotifyAccess=</varname><option>exec</option>. Conversely, if an auxiliary process of the unit
+ sends an <function>sd_notify()</function> message and immediately exits, the service manager might not be
+ able to properly attribute the message to the unit, and thus will ignore it, even if
+ <varname>NotifyAccess=</varname><option>all</option> is set for it. To address this
+ <command>systemd-notify</command> will wait until the notification message has been processed by the
+ service manager. When <option>--no-block</option> is used, this synchronization for reception of
+ notifications is disabled, and hence the aforementioned race may occur if the invoking process is not the
+ service manager or spawned by the service manager.</para>
<para>Hence, <command>systemd-notify</command> will first attempt to invoke <function>sd_notify()</function>
pretending to have the PID of the invoking process. This will only succeed when invoked with sufficient privileges.
@@ -66,7 +67,6 @@
— appears as sender of the message, which in turn is helpful if the shell process is the main process of a service,
due to the limitations of <varname>NotifyAccess=</varname><option>all</option>. Use the <option>--pid=</option>
switch to tweak this behaviour.</para>
-
</refsect1>
<refsect1>
@@ -78,22 +78,42 @@
<varlistentry>
<term><option>--ready</option></term>
- <listitem><para>Inform the init system about service start-up
- completion. This is equivalent to <command>systemd-notify
- READY=1</command>. For details about the semantics of this
- option see
+ <listitem><para>Inform the invoking service manager about service start-up or configuration reload
+ completion. This is equivalent to <command>systemd-notify READY=1</command>. For details about the
+ semantics of this option see
+ <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--reloading</option></term>
+
+ <listitem><para>Inform the invoking service manager about the beginning of a configuration reload
+ cycle. This is equivalent to <command>systemd-notify RELOADING=1</command> (but implicitly also sets
+ a <varname>MONOTONIC_USEC=</varname> field as required for <varname>Type=notify-reload</varname>
+ services, see
+ <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ for details). For details about the semantics of this option see
+ <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--stopping</option></term>
+
+ <listitem><para>Inform the invoking service manager about the beginning of the shutdown phase of the
+ service. This is equivalent to <command>systemd-notify STOPPING=1</command>. For details about the
+ semantics of this option see
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--pid=</option></term>
- <listitem><para>Inform the service manager about the main PID of the daemon. Takes a PID as
+ <listitem><para>Inform the service manager about the main PID of the service. Takes a PID as
argument. If the argument is specified as <literal>auto</literal> or omitted, the PID of the process
that invoked <command>systemd-notify</command> is used, except if that's the service manager. If the
argument is specified as <literal>self</literal>, the PID of the <command>systemd-notify</command>
command itself is used, and if <literal>parent</literal> is specified the calling process' PID is
- used — even if it is the service manager. This is equivalent to <command>systemd-notify
+ used — even if it is the service manager. The latter is equivalent to <command>systemd-notify
MAINPID=$PID</command>. For details about the semantics of this option see
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
</varlistentry>
@@ -110,27 +130,26 @@
<varlistentry>
<term><option>--status=</option></term>
- <listitem><para>Send a free-form status string for the daemon
- to the init systemd. This option takes the status string as
- argument. This is equivalent to <command>systemd-notify
- STATUS=…</command>. For details about the semantics of this
- option see
- <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
+ <listitem><para>Send a free-form human readable status string for the daemon to the service
+ manager. This option takes the status string as argument. This is equivalent to
+ <command>systemd-notify STATUS=…</command>. For details about the semantics of this option see
+ <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>. This
+ information is shown in
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+ <command>status</command> output, among other places.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--booted</option></term>
- <listitem><para>Returns 0 if the system was booted up with
- systemd, non-zero otherwise. If this option is passed, no
- message is sent. This option is hence unrelated to the other
- options. For details about the semantics of this option, see
+ <listitem><para>Returns 0 if the system was booted up with systemd, non-zero otherwise. If this
+ option is passed, no message is sent. This option is hence unrelated to the other options. For
+ details about the semantics of this option, see
<citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>. An
alternate way to check for this state is to call
- <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
- with the <command>is-system-running</command> command. It will
- return <literal>offline</literal> if the system was not booted
- with systemd. </para></listitem>
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> with
+ the <command>is-system-running</command> command. It will return <literal>offline</literal> if the
+ system was not booted with systemd. </para></listitem>
</varlistentry>
<varlistentry>
@@ -162,9 +181,8 @@
<example>
<title>Start-up Notification and Status Updates</title>
- <para>A simple shell daemon that sends start-up notifications
- after having set up its communication channel. During runtime it
- sends further status updates to the init system:</para>
+ <para>A simple shell daemon that sends start-up notifications after having set up its communication
+ channel. During runtime it sends further status updates to the init system:</para>
<programlisting>#!/bin/sh
@@ -192,5 +210,4 @@ done</programlisting>
<citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
-
</refentry>
diff --git a/src/notify/notify.c b/src/notify/notify.c
index 7b23e7bdb0..2d4900a110 100644
--- a/src/notify/notify.c
+++ b/src/notify/notify.c
@@ -23,6 +23,8 @@
#include "util.h"
static bool arg_ready = false;
+static bool arg_reloading = false;
+static bool arg_stopping = false;
static pid_t arg_pid = 0;
static const char *arg_status = NULL;
static bool arg_booted = false;
@@ -42,7 +44,10 @@ static int help(void) {
"\n%sNotify the init system about service status updates.%s\n\n"
" -h --help Show this help\n"
" --version Show package version\n"
- " --ready Inform the init system about service start-up completion\n"
+ " --ready Inform the service manager about service start-up/reload\n"
+ " completion\n"
+ " --reloading Inform the service manager about configuration reloading\n"
+ " --stopping Inform the service manager about service shutdown\n"
" --pid[=PID] Set main PID of daemon\n"
" --uid=USER Set user to send from\n"
" --status=TEXT Set status text\n"
@@ -81,6 +86,8 @@ static int parse_argv(int argc, char *argv[]) {
enum {
ARG_READY = 0x100,
+ ARG_RELOADING,
+ ARG_STOPPING,
ARG_VERSION,
ARG_PID,
ARG_STATUS,
@@ -93,6 +100,8 @@ static int parse_argv(int argc, char *argv[]) {
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, ARG_VERSION },
{ "ready", no_argument, NULL, ARG_READY },
+ { "reloading", no_argument, NULL, ARG_RELOADING },
+ { "stopping", no_argument, NULL, ARG_STOPPING },
{ "pid", optional_argument, NULL, ARG_PID },
{ "status", required_argument, NULL, ARG_STATUS },
{ "booted", no_argument, NULL, ARG_BOOTED },
@@ -120,6 +129,14 @@ static int parse_argv(int argc, char *argv[]) {
arg_ready = true;
break;
+ case ARG_RELOADING:
+ arg_reloading = true;
+ break;
+
+ case ARG_STOPPING:
+ arg_stopping = true;
+ break;
+
case ARG_PID:
if (isempty(optarg) || streq(optarg, "auto")) {
arg_pid = getppid();
@@ -176,6 +193,8 @@ static int parse_argv(int argc, char *argv[]) {
if (optind >= argc &&
!arg_ready &&
+ !arg_stopping &&
+ !arg_reloading &&
!arg_status &&
!arg_pid &&
!arg_booted) {
@@ -187,10 +206,10 @@ static int parse_argv(int argc, char *argv[]) {
}
static int run(int argc, char* argv[]) {
- _cleanup_free_ char *status = NULL, *cpid = NULL, *n = NULL;
+ _cleanup_free_ char *status = NULL, *cpid = NULL, *n = NULL, *monotonic_usec = NULL;
_cleanup_strv_free_ char **final_env = NULL;
- char* our_env[4];
- unsigned i = 0;
+ char* our_env[7];
+ size_t i = 0;
pid_t source_pid;
int r;
@@ -212,9 +231,21 @@ static int run(int argc, char* argv[]) {
return r <= 0;
}
+ if (arg_reloading) {
+ our_env[i++] = (char*) "RELOADING=1";
+
+ if (asprintf(&monotonic_usec, "MONOTONIC_USEC=" USEC_FMT, now(CLOCK_MONOTONIC)) < 0)
+ return log_oom();
+
+ our_env[i++] = monotonic_usec;
+ }
+
if (arg_ready)
our_env[i++] = (char*) "READY=1";
+ if (arg_stopping)
+ our_env[i++] = (char*) "STOPPING=1";
+
if (arg_status) {
status = strjoin("STATUS=", arg_status);
if (!status)
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