man/systemd-socket-proxyd.xml

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   6   SPDX-License-Identifier: LGPL-2.1+
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   8   Copyright © 2013 David Strauss
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  10 <refentry id="systemd-socket-proxyd"
  11     xmlns:xi="http://www.w3.org/2001/XInclude">
  12
  13   <refentryinfo>
  14     <title>systemd-socket-proxyd</title>
  15     <productname>systemd</productname>
  16     <authorgroup>
  17       <author>
  18         <contrib>Developer</contrib>
  19         <firstname>David</firstname>
  20         <surname>Strauss</surname>
  21         <email>david@davidstrauss.net</email>
  22       </author>
  23     </authorgroup>
  24   </refentryinfo>
  25   <refmeta>
  26     <refentrytitle>systemd-socket-proxyd</refentrytitle>
  27     <manvolnum>8</manvolnum>
  28   </refmeta>
  29   <refnamediv>
  30     <refname>systemd-socket-proxyd</refname>
  31     <refpurpose>Bidirectionally proxy local sockets to another (possibly remote) socket.</refpurpose>
  32   </refnamediv>
  33   <refsynopsisdiv>
  34     <cmdsynopsis>
  35       <command>systemd-socket-proxyd</command>
  36       <arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg>
  37       <arg choice="plain"><replaceable>HOST</replaceable>:<replaceable>PORT</replaceable></arg>
  38     </cmdsynopsis>
  39     <cmdsynopsis>
  40       <command>systemd-socket-proxyd</command>
  41       <arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg>
  42       <arg choice="plain"><replaceable>UNIX-DOMAIN-SOCKET-PATH</replaceable>
  43       </arg>
  44     </cmdsynopsis>
  45   </refsynopsisdiv>
  46   <refsect1>
  47     <title>Description</title>
  48     <para>
  49     <command>systemd-socket-proxyd</command> is a generic
  50     socket-activated network socket forwarder proxy daemon for IPv4,
  51     IPv6 and UNIX stream sockets. It may be used to bi-directionally
  52     forward traffic from a local listening socket to a local or remote
  53     destination socket.</para>
  54
  55     <para>One use of this tool is to provide socket activation support
  56     for services that do not natively support socket activation. On
  57     behalf of the service to activate, the proxy inherits the socket
  58     from systemd, accepts each client connection, opens a connection
  59     to a configured server for each client, and then bidirectionally
  60     forwards data between the two.</para>
  61     <para>This utility's behavior is similar to
  62     <citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
  63     The main differences for <command>systemd-socket-proxyd</command>
  64     are support for socket activation with
  65     <literal>Accept=false</literal> and an event-driven
  66     design that scales better with the number of
  67     connections.</para>
  68   </refsect1>
  69   <refsect1>
  70     <title>Options</title>
  71     <para>The following options are understood:</para>
  72     <variablelist>
  73       <xi:include href="standard-options.xml" xpointer="help" />
  74       <xi:include href="standard-options.xml" xpointer="version" />
  75       <varlistentry>
  76         <term><option>--connections-max=</option></term>
  77         <term><option>-c</option></term>
  78
  79         <listitem><para>Sets the maximum number of simultaneous connections, defaults to 256.
  80         If the limit of concurrent connections is reached further connections will be refused.</para></listitem>
  81       </varlistentry>
  82     </variablelist>
  83   </refsect1>
  84   <refsect1>
  85     <title>Exit status</title>
  86     <para>On success, 0 is returned, a non-zero failure
  87     code otherwise.</para>
  88   </refsect1>
  89   <refsect1>
  90     <title>Examples</title>
  91     <refsect2>
  92       <title>Simple Example</title>
  93       <para>Use two services with a dependency and no namespace
  94       isolation.</para>
  95       <example>
  96         <title>proxy-to-nginx.socket</title>
  97         <programlisting><![CDATA[[Socket]
  98 ListenStream=80
  99
 100 [Install]
 101 WantedBy=sockets.target]]></programlisting>
 102       </example>
 103       <example>
 104         <title>proxy-to-nginx.service</title>
 105         <programlisting><![CDATA[[Unit]
 106 Requires=nginx.service
 107 After=nginx.service
 108 Requires=proxy-to-nginx.socket
 109 After=proxy-to-nginx.socket
 110
 111 [Service]
 112 ExecStart=/usr/lib/systemd/systemd-socket-proxyd /run/nginx/socket
 113 PrivateTmp=yes
 114 PrivateNetwork=yes]]></programlisting>
 115       </example>
 116       <example>
 117         <title>nginx.conf</title>
 118         <programlisting>
 119 <![CDATA[[…]
 120 server {
 121     listen       unix:/run/nginx/socket;
 122     […]]]>
 123 </programlisting>
 124       </example>
 125       <example>
 126         <title>Enabling the proxy</title>
 127         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 128 $ curl http://localhost:80/]]></programlisting>
 129       </example>
 130     </refsect2>
 131     <refsect2>
 132       <title>Namespace Example</title>
 133       <para>Similar as above, but runs the socket proxy and the main
 134       service in the same private namespace, assuming that
 135       <filename>nginx.service</filename> has
 136       <varname>PrivateTmp=</varname> and
 137       <varname>PrivateNetwork=</varname> set, too.</para>
 138       <example>
 139         <title>proxy-to-nginx.socket</title>
 140         <programlisting><![CDATA[[Socket]
 141 ListenStream=80
 142
 143 [Install]
 144 WantedBy=sockets.target]]></programlisting>
 145       </example>
 146       <example>
 147         <title>proxy-to-nginx.service</title>
 148         <programlisting><![CDATA[[Unit]
 149 Requires=nginx.service
 150 After=nginx.service
 151 Requires=proxy-to-nginx.socket
 152 After=proxy-to-nginx.socket
 153 JoinsNamespaceOf=nginx.service
 154
 155 [Service]
 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>