<listitem><para>In the child, call
<function>fork()</function> again, to
- ensure the daemon can never re-aquire
+ ensure the daemon can never re-acquire
a terminal again.</para></listitem>
<listitem><para>Call <function>exit()</function> in the
communication channels are established already, and no
request is lost because client requests will be queued
by the bus system (in case of D-Bus) or the kernel (in
- case of sockets), until the activation
+ case of sockets), until the activation is
completed.</para>
<refsect2>
activation of daemons. However, the primary
advantage of this scheme is that all providers
and all consumers of the sockets can be
- started in parallel as soon als all sockets
+ started in parallel as soon as all sockets
are established. In addition to that daemons
can be restarted with losing only a minimal
number of client transactions or even any
the hardware of the respective kind is plugged
in or otherwise becomes available. In a
new-style init system it is possible to bind
- activation to hardware plug/unplug events. In systemd,
- kernel devices appearing in the sysfs/udev
- device tree can be exposed as units if they
- are tagged with the string
+ activation to hardware plug/unplug events. In
+ systemd, kernel devices appearing in the
+ sysfs/udev device tree can be exposed as units
+ if they are tagged with the string
"<literal>systemd</literal>". Like any other
kind of unit they may then pull in other units
when activated (i.e. Plugged in) and thus
<filename>bluetoothd.service</filename> via
controlling a
<filename>bluetooth.target.wants/</filename>
- symlink uniformly with a tool like
- <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ symlink uniformly with a command like
+ <command>enable</command> of
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
instead of manipulating the udev
ruleset.</para>
</refsect2>
to the CPU and IO schedulers. If a process
executed by the init system shall not
negatively impact the amount of CPU or IO
- bandwith available to other processes, it
+ bandwidth available to other processes, it
should be configured with
<varname>CPUSchedulingPolicy=idle</varname>
and/or
<listitem><para>If your daemon
registers a D-Bus name on the bus,
make sure to use
- <varname>Type=dbus</varname> if
+ <varname>Type=dbus</varname> in the
+ service file if
possible.</para></listitem>
<listitem><para>Make sure to set a
operating
system-independent.</para></listitem>
+ <listitem><para>Since not all syslog
+ implementations are socket-activatable
+ yet, it is recommended to place an
+ <varname>After=syslog.target</varname>
+ dependency in service files for
+ daemons that can log to
+ syslog. <filename>syslog.target</filename>
+ then either pulls in the syslog daemon
+ itself or simply the activation
+ socket. A <varname>Wants=</varname> or
+ even <varname>Requires=</varname>
+ dependency should generally not be
+ added, since it should be up to the
+ administrator whether he wants to
+ enable logging or not, and most syslog
+ clients work fine if no log daemon is
+ running.</para></listitem>
+
<listitem><para>Make sure to include
- an <literal>[Install]</literal> section including
- installation information for the unit
- file. See
+ an <literal>[Install]</literal>
+ section including installation
+ information for the unit file. See
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details. To activate your service
on boot make sure to add a
<varname>WantedBy=multi-user.target</varname>
or
- <varname>WantedBy=graphical.target</varname> directive.</para></listitem>
+ <varname>WantedBy=graphical.target</varname>
+ directive. To activate your socket on
+ boot, make sure to add
+ <varname>WantedBy=sockets.target</varname>. Usually
+ you also want to make sure that when
+ your service is installed your socket
+ is installed too, hence add
+ <varname>Also=foo.socket</varname> in
+ your service file
+ <filename>foo.service</filename>, for
+ a hypothetical program
+ <filename>foo</filename>.</para></listitem>
</orderedlist>
</refsect2>
install their systemd unit files in the
directory returned by <command>pkg-config
systemd
- --variable=systemdsystemnunitdir</command>
- (for system services),
- resp. <command>pkg-config systemd
- --variable=systemdsessionunitdir</command>
- (for session services). This will make the
+ --variable=systemdsystemunitdir</command> (for
+ system services), resp. <command>pkg-config
+ systemd
+ --variable=systemduserunitdir</command>
+ (for user services). This will make the
services available in the system on explicit
request but not activate them automatically
during boot. Optionally, during package
installation (e.g. <command>rpm -i</command>
by the administrator) symlinks should be
created in the systemd configuration
- directories via the
- <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ directories via the <command>enable</command>
+ command of the
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
tool, to activate them automatically on
boot.</para>
AC_ARG_WITH([systemdsystemunitdir],
AS_HELP_STRING([--with-systemdsystemunitdir=DIR], [Directory for systemd service files]),
[], [with_systemdsystemunitdir=$($PKG_CONFIG --variable=systemdsystemunitdir systemd)])
-AC_SUBST([systemdsystemunitdir], [$with_systemdsystemunitdir])
-AM_CONDITIONAL(HAVE_SYSTEMD, [test -n "$with_systemdsystemunitdir"])</programlisting>
+if test "x$with_systemdsystemunitdir" != xno; then
+ AC_SUBST([systemdsystemunitdir], [$with_systemdsystemunitdir])
+fi
+AM_CONDITIONAL(HAVE_SYSTEMD, [test -n "$with_systemdsystemunitdir" -a "x$with_systemdsystemunitdir" != xno ])</programlisting>
<para>This snippet allows automatic
installation of the unit files on systemd
machines, and optionally allows their
installation even on machines lacking
systemd. (Modification of this snippet for the
- session unit directory is left as excercise to the
+ user unit directory is left as excercise to the
reader.)</para>
<para>Additionally, to ensure that
package managers:</para>
<programlisting>%post
-/usr/bin/systemd-install enable foobar.service foobar.socket >/dev/null 2>&1 || :
+if [ $1 -eq 1 ]; then
+ # On install (not upgrade), enable (but don't start) the
+ # units by default
+ /bin/systemctl enable foobar.service foobar.socket >/dev/null 2>&1 || :
+
+ # Alternatively, just call
+ # /bin/systemctl daemon-reload >/dev/null 2>&1 || :
+ # here, if the daemon should not be enabled by default on
+ # installation
+fi
%preun
-if [ "$1" -eq 0 ]; then
- /usr/bin/systemd-install disable foobar.service foobar.socket >/dev/null 2>&1 || :
+if [ $1 -eq 0 ]; then
+ # On uninstall (not upgrade), disable and stop the units
+ /bin/systemctl disable foobar.service foobar.socket >/dev/null 2>&1 || :
+ /bin/systemctl stop foobar.service foobar.socket >/dev/null 2>&1 || :
+fi
+
+%postun
+# Reload init system configuration, to make systemd honour changed
+# or deleted unit files
+/bin/systemctl daemon-reload >/dev/null 2>&1 || :
+if [ $1 -ge 1 ] ; then
+ # On upgrade (not uninstall), optionally, restart the daemon
+ /bin/systemctl try-restart foobar.service >/dev/null 2>&1 || :
+fi</programlisting>
+
+ <para>Depending on whether your service should
+ or should not be started/stopped/restarted
+ during package installation, deinstallation or
+ upgrade, a different set of commands may be
+ specified. See
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ for details.</para>
+
+ <para>To facilitate upgrades from a package
+ version that shipped only SysV init scripts to
+ a package version that ships both a SysV init
+ script and a native systemd service file, use
+ a fragment like the following:</para>
+
+ <programlisting>%triggerun -- foobar < 0.47.11-1
+if /sbin/chkconfig foobar ; then
+ /bin/systemctl enable foobar.service foobar.socket >/dev/null 2>&1 || :
fi</programlisting>
+ <para>Where 0.47.11-1 is the first package
+ version that includes the native unit
+ file. This fragment will ensure that the first
+ time the unit file is installed it will be
+ enabled if and only if the SysV init script is
+ enabled, thus making sure that the enable
+ status is not changed. Note that
+ <command>chkconfig</command> is a command
+ specific to Fedora which can be used to check
+ whether a SysV init script is enabled. Other
+ operating systems will have to use different
+ commands here.</para>
</refsect2>
</refsect1>
<para>Since new-style init systems such as systemd are
compatible with traditional SysV init systems it is
not strictly necessary to port existing daemons to the
- new style. However doing this offers additional
- functionality to the daemons as well as it simplifies
+ new style. However doing so offers additional
+ functionality to the daemons as well as simplifying
integration into new-style init systems.</para>
<para>To port an existing SysV compatible daemon the
left-over file descriptors are passed to
executed processes, it might be a good choice
to simply skip the closing of all remaining
- open file descriptors if file descriptors are
+ open file descriptors if sockets are
passed.</para></listitem>
<listitem><para>Write and install a systemd
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
~ianmdlvl / elogind.git / blobdiff