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
  57     <para>Note that <command>systemd-socket-proxyd</command> will not forward socket side channel
  58     information, i.e. will not forward <constant>SCM_RIGHTS</constant>, <constant>SCM_CREDENTIALS</constant>,
  59     <constant>SCM_SECURITY</constant>, <constant>SO_PEERCRED</constant>, <constant>SO_PEERPIDFD</constant>,
  60     <constant>SO_PEERSEC</constant>, <constant>SO_PEERGROUPS</constant> and similar.</para>
  61   </refsect1>
  62   <refsect1>
  63     <title>Options</title>
  64     <para>The following options are understood:</para>
  65     <variablelist>
  66       <xi:include href="standard-options.xml" xpointer="help" />
  67       <xi:include href="standard-options.xml" xpointer="version" />
  68       <varlistentry>
  69         <term><option>--connections-max=</option></term>
  70         <term><option>-c</option></term>
  71
  72         <listitem><para>Sets the maximum number of simultaneous connections, defaults to 256.
  73         If the limit of concurrent connections is reached further connections will be refused.</para>
  74
  75         <xi:include href="version-info.xml" xpointer="v233"/></listitem>
  76       </varlistentry>
  77       <varlistentry>
  78         <term><option>--exit-idle-time=</option></term>
  79
  80         <listitem><para>Sets the time before exiting when there are no connections, defaults to
  81         <constant>infinity</constant>. Takes a unit-less value in seconds, or a time span value such
  82         as <literal>5min 20s</literal>.</para>
  83
  84         <xi:include href="version-info.xml" xpointer="v246"/></listitem>
  85       </varlistentry>
  86     </variablelist>
  87   </refsect1>
  88   <refsect1>
  89     <title>Exit status</title>
  90     <para>On success, 0 is returned, a non-zero failure
  91     code otherwise.</para>
  92   </refsect1>
  93   <refsect1>
  94     <title>Examples</title>
  95     <refsect2>
  96       <title>Simple Example</title>
  97       <para>Use two services with a dependency and no namespace
  98       isolation.</para>
  99       <example>
 100         <title>proxy-to-nginx.socket</title>
 101         <programlisting><![CDATA[[Socket]
 102 ListenStream=80
 103
 104 [Install]
 105 WantedBy=sockets.target]]></programlisting>
 106       </example>
 107       <example>
 108         <title>proxy-to-nginx.service</title>
 109         <programlisting><![CDATA[[Unit]
 110 Requires=nginx.service
 111 After=nginx.service
 112 Requires=proxy-to-nginx.socket
 113 After=proxy-to-nginx.socket
 114
 115 [Service]
 116 Type=notify
 117 ExecStart=/usr/lib/systemd/systemd-socket-proxyd /run/nginx/socket
 118 PrivateTmp=yes
 119 PrivateNetwork=yes]]></programlisting>
 120       </example>
 121       <example>
 122         <title>nginx.conf</title>
 123         <programlisting>
 124 <![CDATA[[…]
 125 server {
 126     listen       unix:/run/nginx/socket;
 127     […]]]>
 128 </programlisting>
 129       </example>
 130       <example>
 131         <title>Enabling the proxy</title>
 132         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 133 $ curl http://localhost:80/]]></programlisting>
 134       </example>
 135       <para>If <filename>nginx.service</filename> has <varname>StopWhenUnneeded=</varname> set, then
 136       passing <option>--exit-idle-time=</option> to <command>systemd-socket-proxyd</command> allows
 137       both services to stop during idle periods.</para>
 138     </refsect2>
 139     <refsect2>
 140       <title>Namespace Example</title>
 141       <para>Similar as above, but runs the socket proxy and the main
 142       service in the same private namespace, assuming that
 143       <filename>nginx.service</filename> has
 144       <varname>PrivateTmp=</varname> and
 145       <varname>PrivateNetwork=</varname> set, too.</para>
 146       <example>
 147         <title>proxy-to-nginx.socket</title>
 148         <programlisting><![CDATA[[Socket]
 149 ListenStream=80
 150
 151 [Install]
 152 WantedBy=sockets.target]]></programlisting>
 153       </example>
 154       <example>
 155         <title>proxy-to-nginx.service</title>
 156         <programlisting><![CDATA[[Unit]
 157 Requires=nginx.service
 158 After=nginx.service
 159 Requires=proxy-to-nginx.socket
 160 After=proxy-to-nginx.socket
 161 JoinsNamespaceOf=nginx.service
 162
 163 [Service]
 164 Type=notify
 165 ExecStart=/usr/lib/systemd/systemd-socket-proxyd 127.0.0.1:8080
 166 PrivateTmp=yes
 167 PrivateNetwork=yes]]></programlisting>
 168       </example>
 169       <example>
 170         <title>nginx.conf</title>
 171         <programlisting><![CDATA[[…]
 172 server {
 173     listen       8080;
 174     […]]]></programlisting>
 175       </example>
 176       <example>
 177         <title>Enabling the proxy</title>
 178         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 179 $ curl http://localhost:80/]]></programlisting>
 180       </example>
 181     </refsect2>
 182   </refsect1>
 183   <refsect1>
 184     <title>See Also</title>
 185     <para><simplelist type="inline">
 186       <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
 187       <member><citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
 188       <member><citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
 189       <member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
 190       <member><citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
 191       <member><citerefentry project='die-net'><refentrytitle>nginx</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
 192       <member><citerefentry project='die-net'><refentrytitle>curl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
 193     </simplelist></para>
 194   </refsect1>
 195 </refentry>