3 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
4 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
5 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
6 <refentry id=
"systemd-socket-proxyd"
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>systemd-socket-proxyd
</title>
11 <productname>systemd
</productname>
14 <refentrytitle>systemd-socket-proxyd
</refentrytitle>
15 <manvolnum>8</manvolnum>
18 <refname>systemd-socket-proxyd
</refname>
19 <refpurpose>Bidirectionally proxy local sockets to another (possibly remote) socket.
</refpurpose>
23 <command>systemd-socket-proxyd
</command>
24 <arg choice=
"opt" rep=
"repeat"><replaceable>OPTIONS
</replaceable></arg>
25 <arg choice=
"plain"><replaceable>HOST
</replaceable>:
<replaceable>PORT
</replaceable></arg>
28 <command>systemd-socket-proxyd
</command>
29 <arg choice=
"opt" rep=
"repeat"><replaceable>OPTIONS
</replaceable></arg>
30 <arg choice=
"plain"><replaceable>UNIX-DOMAIN-SOCKET-PATH
</replaceable>
35 <title>Description
</title>
37 <command>systemd-socket-proxyd
</command> is a generic
38 socket-activated network socket forwarder proxy daemon for IPv4,
39 IPv6 and UNIX stream sockets. It may be used to bi-directionally
40 forward traffic from a local listening socket to a local or remote
41 destination socket.
</para>
43 <para>One use of this tool is to provide socket activation support
44 for services that do not natively support socket activation. On
45 behalf of the service to activate, the proxy inherits the socket
46 from systemd, accepts each client connection, opens a connection
47 to a configured server for each client, and then bidirectionally
48 forwards data between the two.
</para>
49 <para>This utility's behavior is similar to
50 <citerefentry project='die-net'
><refentrytitle>socat
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
51 The main differences for
<command>systemd-socket-proxyd
</command>
52 are support for socket activation with
53 <literal>Accept=no
</literal> and an event-driven
54 design that scales better with the number of
58 <title>Options
</title>
59 <para>The following options are understood:
</para>
61 <xi:include href=
"standard-options.xml" xpointer=
"help" />
62 <xi:include href=
"standard-options.xml" xpointer=
"version" />
64 <term><option>--connections-max=
</option></term>
65 <term><option>-c
</option></term>
67 <listitem><para>Sets the maximum number of simultaneous connections, defaults to
256.
68 If the limit of concurrent connections is reached further connections will be refused.
</para></listitem>
71 <term><option>--exit-idle-time=
</option></term>
73 <listitem><para>Sets the time before exiting when there are no connections, defaults to
74 <constant>infinity
</constant>. Takes a unit-less value in seconds, or a time span value such
75 as
<literal>5min
20s
</literal>.
</para></listitem>
80 <title>Exit status
</title>
81 <para>On success,
0 is returned, a non-zero failure
82 code otherwise.
</para>
85 <title>Examples
</title>
87 <title>Simple Example
</title>
88 <para>Use two services with a dependency and no namespace
91 <title>proxy-to-nginx.socket
</title>
92 <programlisting><![CDATA[[Socket]
96 WantedBy=sockets.target]]
></programlisting>
99 <title>proxy-to-nginx.service
</title>
100 <programlisting><![CDATA[[Unit]
101 Requires=nginx.service
103 Requires=proxy-to-nginx.socket
104 After=proxy-to-nginx.socket
107 ExecStart=/usr/lib/systemd/systemd-socket-proxyd /run/nginx/socket
109 PrivateNetwork=yes]]
></programlisting>
112 <title>nginx.conf
</title>
116 listen unix:/run/nginx/socket;
121 <title>Enabling the proxy
</title>
122 <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
123 $ curl http://localhost:
80/]]
></programlisting>
125 <para>If
<filename>nginx.service
</filename> has
<varname>StopWhenUnneeded=
</varname> set, then
126 passing
<option>--exit-idle-time=
</option> to
<command>systemd-socket-proxyd
</command> allows
127 both services to stop during idle periods.
</para>
130 <title>Namespace Example
</title>
131 <para>Similar as above, but runs the socket proxy and the main
132 service in the same private namespace, assuming that
133 <filename>nginx.service
</filename> has
134 <varname>PrivateTmp=
</varname> and
135 <varname>PrivateNetwork=
</varname> set, too.
</para>
137 <title>proxy-to-nginx.socket
</title>
138 <programlisting><![CDATA[[Socket]
142 WantedBy=sockets.target]]
></programlisting>
145 <title>proxy-to-nginx.service
</title>
146 <programlisting><![CDATA[[Unit]
147 Requires=nginx.service
149 Requires=proxy-to-nginx.socket
150 After=proxy-to-nginx.socket
151 JoinsNamespaceOf=nginx.service
154 ExecStart=/usr/lib/systemd/systemd-socket-proxyd
127.0.0.1:
8080
156 PrivateNetwork=yes]]
></programlisting>
159 <title>nginx.conf
</title>
160 <programlisting><![CDATA[[…]
163 […]]]
></programlisting>
166 <title>Enabling the proxy
</title>
167 <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
168 $ curl http://localhost:
80/]]
></programlisting>
173 <title>See Also
</title>
175 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
176 <citerefentry><refentrytitle>systemd.socket
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
177 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
178 <citerefentry><refentrytitle>systemctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
179 <citerefentry project='die-net'
><refentrytitle>socat
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
180 <citerefentry project='die-net'
><refentrytitle>nginx
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
181 <citerefentry project='die-net'
><refentrytitle>curl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>