man/systemd-socket-proxyd.xml

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   3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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   5 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
   6 <refentry id="systemd-socket-proxyd"
   7     xmlns:xi="http://www.w3.org/2001/XInclude">
   8
   9   <refentryinfo>
  10     <title>systemd-socket-proxyd</title>
  11     <productname>systemd</productname>
  12   </refentryinfo>
  13   <refmeta>
  14     <refentrytitle>systemd-socket-proxyd</refentrytitle>
  15     <manvolnum>8</manvolnum>
  16   </refmeta>
  17   <refnamediv>
  18     <refname>systemd-socket-proxyd</refname>
  19     <refpurpose>Bidirectionally proxy local sockets to another (possibly remote) socket</refpurpose>
  20   </refnamediv>
  21   <refsynopsisdiv>
  22     <cmdsynopsis>
  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>
  26     </cmdsynopsis>
  27     <cmdsynopsis>
  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>
  31       </arg>
  32     </cmdsynopsis>
  33   </refsynopsisdiv>
  34   <refsect1>
  35     <title>Description</title>
  36     <para>
  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>
  42
  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
  55     connections.</para>
  56   </refsect1>
  57   <refsect1>
  58     <title>Options</title>
  59     <para>The following options are understood:</para>
  60     <variablelist>
  61       <xi:include href="standard-options.xml" xpointer="help" />
  62       <xi:include href="standard-options.xml" xpointer="version" />
  63       <varlistentry>
  64         <term><option>--connections-max=</option></term>
  65         <term><option>-c</option></term>
  66
  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>
  69       </varlistentry>
  70       <varlistentry>
  71         <term><option>--exit-idle-time=</option></term>
  72
  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>
  76       </varlistentry>
  77     </variablelist>
  78   </refsect1>
  79   <refsect1>
  80     <title>Exit status</title>
  81     <para>On success, 0 is returned, a non-zero failure
  82     code otherwise.</para>
  83   </refsect1>
  84   <refsect1>
  85     <title>Examples</title>
  86     <refsect2>
  87       <title>Simple Example</title>
  88       <para>Use two services with a dependency and no namespace
  89       isolation.</para>
  90       <example>
  91         <title>proxy-to-nginx.socket</title>
  92         <programlisting><![CDATA[[Socket]
  93 ListenStream=80
  94
  95 [Install]
  96 WantedBy=sockets.target]]></programlisting>
  97       </example>
  98       <example>
  99         <title>proxy-to-nginx.service</title>
 100         <programlisting><![CDATA[[Unit]
 101 Requires=nginx.service
 102 After=nginx.service
 103 Requires=proxy-to-nginx.socket
 104 After=proxy-to-nginx.socket
 105
 106 [Service]
 107 Type=notify
 108 ExecStart=/usr/lib/systemd/systemd-socket-proxyd /run/nginx/socket
 109 PrivateTmp=yes
 110 PrivateNetwork=yes]]></programlisting>
 111       </example>
 112       <example>
 113         <title>nginx.conf</title>
 114         <programlisting>
 115 <![CDATA[[…]
 116 server {
 117     listen       unix:/run/nginx/socket;
 118     […]]]>
 119 </programlisting>
 120       </example>
 121       <example>
 122         <title>Enabling the proxy</title>
 123         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 124 $ curl http://localhost:80/]]></programlisting>
 125       </example>
 126       <para>If <filename>nginx.service</filename> has <varname>StopWhenUnneeded=</varname> set, then
 127       passing <option>--exit-idle-time=</option> to <command>systemd-socket-proxyd</command> allows
 128       both services to stop during idle periods.</para>
 129     </refsect2>
 130     <refsect2>
 131       <title>Namespace Example</title>
 132       <para>Similar as above, but runs the socket proxy and the main
 133       service in the same private namespace, assuming that
 134       <filename>nginx.service</filename> has
 135       <varname>PrivateTmp=</varname> and
 136       <varname>PrivateNetwork=</varname> set, too.</para>
 137       <example>
 138         <title>proxy-to-nginx.socket</title>
 139         <programlisting><![CDATA[[Socket]
 140 ListenStream=80
 141
 142 [Install]
 143 WantedBy=sockets.target]]></programlisting>
 144       </example>
 145       <example>
 146         <title>proxy-to-nginx.service</title>
 147         <programlisting><![CDATA[[Unit]
 148 Requires=nginx.service
 149 After=nginx.service
 150 Requires=proxy-to-nginx.socket
 151 After=proxy-to-nginx.socket
 152 JoinsNamespaceOf=nginx.service
 153
 154 [Service]
 155 Type=notify
 156 ExecStart=/usr/lib/systemd/systemd-socket-proxyd 127.0.0.1:8080
 157 PrivateTmp=yes
 158 PrivateNetwork=yes]]></programlisting>
 159       </example>
 160       <example>
 161         <title>nginx.conf</title>
 162         <programlisting><![CDATA[[…]
 163 server {
 164     listen       8080;
 165     […]]]></programlisting>
 166       </example>
 167       <example>
 168         <title>Enabling the proxy</title>
 169         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 170 $ curl http://localhost:80/]]></programlisting>
 171       </example>
 172     </refsect2>
 173   </refsect1>
 174   <refsect1>
 175     <title>See Also</title>
 176     <para>
 177       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 178       <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 179       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 180       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 181       <citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 182       <citerefentry project='die-net'><refentrytitle>nginx</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 183       <citerefentry project='die-net'><refentrytitle>curl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 184     </para>
 185   </refsect1>
 186 </refentry>