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     </variablelist>
  71   </refsect1>
  72   <refsect1>
  73     <title>Exit status</title>
  74     <para>On success, 0 is returned, a non-zero failure
  75     code otherwise.</para>
  76   </refsect1>
  77   <refsect1>
  78     <title>Examples</title>
  79     <refsect2>
  80       <title>Simple Example</title>
  81       <para>Use two services with a dependency and no namespace
  82       isolation.</para>
  83       <example>
  84         <title>proxy-to-nginx.socket</title>
  85         <programlisting><![CDATA[[Socket]
  86 ListenStream=80
  87
  88 [Install]
  89 WantedBy=sockets.target]]></programlisting>
  90       </example>
  91       <example>
  92         <title>proxy-to-nginx.service</title>
  93         <programlisting><![CDATA[[Unit]
  94 Requires=nginx.service
  95 After=nginx.service
  96 Requires=proxy-to-nginx.socket
  97 After=proxy-to-nginx.socket
  98
  99 [Service]
 100 ExecStart=/usr/lib/systemd/systemd-socket-proxyd /run/nginx/socket
 101 PrivateTmp=yes
 102 PrivateNetwork=yes]]></programlisting>
 103       </example>
 104       <example>
 105         <title>nginx.conf</title>
 106         <programlisting>
 107 <![CDATA[[…]
 108 server {
 109     listen       unix:/run/nginx/socket;
 110     […]]]>
 111 </programlisting>
 112       </example>
 113       <example>
 114         <title>Enabling the proxy</title>
 115         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 116 $ curl http://localhost:80/]]></programlisting>
 117       </example>
 118     </refsect2>
 119     <refsect2>
 120       <title>Namespace Example</title>
 121       <para>Similar as above, but runs the socket proxy and the main
 122       service in the same private namespace, assuming that
 123       <filename>nginx.service</filename> has
 124       <varname>PrivateTmp=</varname> and
 125       <varname>PrivateNetwork=</varname> set, too.</para>
 126       <example>
 127         <title>proxy-to-nginx.socket</title>
 128         <programlisting><![CDATA[[Socket]
 129 ListenStream=80
 130
 131 [Install]
 132 WantedBy=sockets.target]]></programlisting>
 133       </example>
 134       <example>
 135         <title>proxy-to-nginx.service</title>
 136         <programlisting><![CDATA[[Unit]
 137 Requires=nginx.service
 138 After=nginx.service
 139 Requires=proxy-to-nginx.socket
 140 After=proxy-to-nginx.socket
 141 JoinsNamespaceOf=nginx.service
 142
 143 [Service]
 144 ExecStart=/usr/lib/systemd/systemd-socket-proxyd 127.0.0.1:8080
 145 PrivateTmp=yes
 146 PrivateNetwork=yes]]></programlisting>
 147       </example>
 148       <example>
 149         <title>nginx.conf</title>
 150         <programlisting><![CDATA[[…]
 151 server {
 152     listen       8080;
 153     […]]]></programlisting>
 154       </example>
 155       <example>
 156         <title>Enabling the proxy</title>
 157         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 158 $ curl http://localhost:80/]]></programlisting>
 159       </example>
 160     </refsect2>
 161   </refsect1>
 162   <refsect1>
 163     <title>See Also</title>
 164     <para>
 165       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 166       <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 167       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 168       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 169       <citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 170       <citerefentry project='die-net'><refentrytitle>nginx</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 171       <citerefentry project='die-net'><refentrytitle>curl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 172     </para>
 173   </refsect1>
 174 </refentry>