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+ -->
   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 ExecStart=/usr/lib/systemd/systemd-socket-proxyd /run/nginx/socket
 108 PrivateTmp=yes
 109 PrivateNetwork=yes]]></programlisting>
 110       </example>
 111       <example>
 112         <title>nginx.conf</title>
 113         <programlisting>
 114 <![CDATA[[…]
 115 server {
 116     listen       unix:/run/nginx/socket;
 117     […]]]>
 118 </programlisting>
 119       </example>
 120       <example>
 121         <title>Enabling the proxy</title>
 122         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 123 $ curl http://localhost:80/]]></programlisting>
 124       </example>
 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>
 128     </refsect2>
 129     <refsect2>
 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>
 136       <example>
 137         <title>proxy-to-nginx.socket</title>
 138         <programlisting><![CDATA[[Socket]
 139 ListenStream=80
 140
 141 [Install]
 142 WantedBy=sockets.target]]></programlisting>
 143       </example>
 144       <example>
 145         <title>proxy-to-nginx.service</title>
 146         <programlisting><![CDATA[[Unit]
 147 Requires=nginx.service
 148 After=nginx.service
 149 Requires=proxy-to-nginx.socket
 150 After=proxy-to-nginx.socket
 151 JoinsNamespaceOf=nginx.service
 152
 153 [Service]
 154 ExecStart=/usr/lib/systemd/systemd-socket-proxyd 127.0.0.1:8080
 155 PrivateTmp=yes
 156 PrivateNetwork=yes]]></programlisting>
 157       </example>
 158       <example>
 159         <title>nginx.conf</title>
 160         <programlisting><![CDATA[[…]
 161 server {
 162     listen       8080;
 163     […]]]></programlisting>
 164       </example>
 165       <example>
 166         <title>Enabling the proxy</title>
 167         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 168 $ curl http://localhost:80/]]></programlisting>
 169       </example>
 170     </refsect2>
 171   </refsect1>
 172   <refsect1>
 173     <title>See Also</title>
 174     <para>
 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>
 182     </para>
 183   </refsect1>
 184 </refentry>