<refsect1>
<title>Description</title>
- <para>A unit configuration file whose name ends in .socket
- encodes information about an IPC or network socket or
- a file system FIFO controlled and supervised by systemd,
- for socket-based activation.</para>
+ <para>A unit configuration file whose name ends in
+ <filename>.socket</filename> encodes information about
+ an IPC or network socket or a file system FIFO
+ controlled and supervised by systemd, for socket-based
+ activation.</para>
<para>This man page lists the configuration options
specific to this unit type. See
for the common options of all unit configuration
files. The common configuration items are configured
in the generic [Unit] and [Install] sections. The
- service specific configuration options are configured
+ socket specific configuration options are configured
in the [Socket] section.</para>
<para>Additional options are listed in
- <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
-
- <para>For each socket file a matching service file (see <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details)
- must exist, describing the service to start on
- incoming traffic on the socket. Depending on the
- setting of <option>Accept=</option> (see below) this
- must either be named like the socket unit, but with
- the suffix replaced; or it must be a template file
- named the same way. Example: a socket file
+ <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ which define the execution environment the
+ <option>ExecStartPre=</option>,
+ <option>ExecStartPost=</option>,
+ <option>ExecStopPre=</option> and
+ <option>ExecStoptPost=</option> commands are executed
+ in.</para>
+
+ <para>For each socket file a matching service file
+ (see
+ <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details) must exist, describing the service to
+ start on incoming traffic on the socket. Depending on
+ the setting of <option>Accept=</option> (see below),
+ this must either be named like the socket unit, but
+ with the suffix replaced; or it must be a template
+ file named the same way. Example: a socket file
<filename>foo.socket</filename> needs a matching
service <filename>foo.service</filename> if
<option>Accept=false</option> is set. If
file <filename>foo@.service</filename> must exist from
which services are instantiated for each incoming
connection.</para>
+
+ <para>Unless <varname>DefaultDependencies=</varname>
+ is set to <option>false</option>, socket units will
+ implicitly have dependencies of type
+ <varname>Requires=</varname> and
+ <varname>After=</varname> on
+ <filename>sysinit.target</filename> as well as
+ dependencies of type <varname>Conflicts=</varname> and
+ <varname>Before=</varname> on
+ <filename>shutdown.target</filename>. These ensure
+ that socket units pull in basic system
+ initialization, and are terminated cleanly prior to
+ system shutdown. Only sockets involved with early
+ boot or late system shutdown should disable this
+ option.</para>
+
+ <para>Socket units may be used to implement on-demand
+ starting of services, as well as parallelized starting
+ of services.</para>
</refsect1>
<refsect1>
this section are shared with other unit types. These
options are documented in
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
- options specific to the [Socket] section of service
+ options specific to the [Socket] section of socket
units are the following:</para>
<variablelist>
regardless whether there is incoming
traffic on them or not.</para>
- <para>If an IP address is used here it
+ <para>If an IP address is used here, it
is often desirable to listen on it
before the interface it is configured
on is up and running, and even
interfaces. This controls the
SO_BINDTODEVICE socket option (see
<citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details). If this option is used
+ for details). If this option is used,
an automatic dependency from this
socket unit on the network interface
device unit
<varlistentry>
<term><varname>DirectoryMode=</varname></term>
<listitem><para>If listening on a file
- system socket of FIFO the parent
+ system socket of FIFO, the parent
directories are automatically created
if needed. This option specifies the
file system access mode used when
- creating these directories. Defaults
- to 0755.</para></listitem>
+ creating these directories. Takes an
+ access mode in octal
+ notation. Defaults to
+ 0755.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>SocketMode=</varname></term>
<listitem><para>If listening on a file
- system socket of FIFO this option
+ system socket of FIFO, this option
specifies the file system access mode
used when creating the file
- node. Defaults to
+ node. Takes an access mode in octal
+ notation. Defaults to
0666.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>Accept=</varname></term>
<listitem><para>Takes a boolean
- argument. If true a service instance
+ argument. If true, a service instance
is spawned for each incoming
connection and only the connection
- socket is passed to it. If false all
+ socket is passed to it. If false, all
listening sockets themselves are
passed to the started service unit,
and only one service unit is spawned
for all connections (also see
above). This value is ignored for
datagram sockets and FIFOs where
- unconditionally a single service unit
+ a single service unit unconditionally
handles all incoming traffic. Defaults
to <option>false</option>. For
- performance reasons it is recommended
+ performance reasons, it is recommended
to write new daemons only in a way
that is suitable for
<option>Accept=false</option>. This
option is mostly useful to allow
daemons designed for usage with
- <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- to work unmodified with system socket
+ <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ to work unmodified with systemd socket
activation.</para></listitem>
</varlistentry>
services instances for, when
<option>Accept=true</option> is
set. If more concurrent connections
- are coming in they will be refused,
+ are coming in, they will be refused
until at least one existing connection
is terminated. This setting has no
effect for sockets configured with
address. Defaults to <option>false</option>.</para></listitem>
</varlistentry>
- <!--
- { "TimeoutSec", config_parse_usec, &u->socket.timeout_usec, "Socket" },
- { "KillMode", config_parse_kill_mode, &u->socket.kill_mode, "Socket" },
--->
+ <varlistentry>
+ <term><varname>TCPCongestion=</varname></term>
+ <listitem><para>Takes a string
+ value. Controls the TCP congestion
+ algorithm used by this socket. Should
+ be one of "westwood", "veno", "cubic",
+ "lp" or any other available algorithm
+ supported by the IP stack. This
+ setting applies only to stream
+ sockets.</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><varname>ExecStartPre=</varname></term>
<term><varname>ExecStartPost=</varname></term>
- <listitem><para>Takes a command line
- that is executed before (resp. after)
- the listening sockets/FIFOs are created and
+ <listitem><para>Takes one or more
+ command lines, which are executed
+ before (resp. after) the listening
+ sockets/FIFOs are created and
bound. The first token of the command
line must be an absolute file name,
then followed by arguments for the
- process. If specified more than once,
- all commands are executed one after
- the other, serially. Use of these
- settings is optional.</para></listitem>
+ process. Multiple command lines may be
+ specified following the same scheme as
+ used for
+ <varname>ExecStartPre=</varname> of
+ service unit files.</para></listitem>
</varlistentry>
<varlistentry>
<listitem><para>Additional commands
that are executed before (resp. after)
the listening sockets/FIFOs are closed
- and removed. If specified more than
- once, all commands are executed one
- after the other, serially. Use of
- these settings is
- optional.</para></listitem>
+ and removed. Multiple command lines
+ may be specified following the same
+ scheme as used for
+ <varname>ExecStartPre=</varname> of
+ service unit files.</para></listitem>
</varlistentry>
-
<varlistentry>
<term><varname>TimeoutSec=</varname></term>
<listitem><para>Configures the time to
<varname>ExecStartPost=</varname>,
<varname>ExecStopPre=</varname> and
<varname>ExecStopPost=</varname> to
- finish. If a comand does not exit
- within the configured time the socket
+ finish. If a command does not exit
+ within the configured time, the socket
will be considered failed and be shut
- down again. All commands still running
+ down again. All commands still running,
will be terminated forcibly via
SIGTERM, and after another delay of
this time with SIGKILL. (See
- <option>KilleMode=</option> below.)
+ <option>KillMode=</option> below.)
Takes a unit-less value in seconds, or
a time span value such as "5min
20s". Pass 0 to disable the timeout
60s.</para></listitem>
</varlistentry>
-
<varlistentry>
<term><varname>KillMode=</varname></term>
<listitem><para>Specifies how
- processes of this service shall be
+ processes of this socket unit shall be
killed. One of
<option>control-group</option>,
<option>process-group</option>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
-
-
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
~ianmdlvl / elogind.git / blobdiff