man/systemd-socket-proxyd.xml

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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   </refentryinfo>
  17   <refmeta>
  18     <refentrytitle>systemd-socket-proxyd</refentrytitle>
  19     <manvolnum>8</manvolnum>
  20   </refmeta>
  21   <refnamediv>
  22     <refname>systemd-socket-proxyd</refname>
  23     <refpurpose>Bidirectionally proxy local sockets to another (possibly remote) socket.</refpurpose>
  24   </refnamediv>
  25   <refsynopsisdiv>
  26     <cmdsynopsis>
  27       <command>systemd-socket-proxyd</command>
  28       <arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg>
  29       <arg choice="plain"><replaceable>HOST</replaceable>:<replaceable>PORT</replaceable></arg>
  30     </cmdsynopsis>
  31     <cmdsynopsis>
  32       <command>systemd-socket-proxyd</command>
  33       <arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg>
  34       <arg choice="plain"><replaceable>UNIX-DOMAIN-SOCKET-PATH</replaceable>
  35       </arg>
  36     </cmdsynopsis>
  37   </refsynopsisdiv>
  38   <refsect1>
  39     <title>Description</title>
  40     <para>
  41     <command>systemd-socket-proxyd</command> is a generic
  42     socket-activated network socket forwarder proxy daemon for IPv4,
  43     IPv6 and UNIX stream sockets. It may be used to bi-directionally
  44     forward traffic from a local listening socket to a local or remote
  45     destination socket.</para>
  46
  47     <para>One use of this tool is to provide socket activation support
  48     for services that do not natively support socket activation. On
  49     behalf of the service to activate, the proxy inherits the socket
  50     from systemd, accepts each client connection, opens a connection
  51     to a configured server for each client, and then bidirectionally
  52     forwards data between the two.</para>
  53     <para>This utility's behavior is similar to
  54     <citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
  55     The main differences for <command>systemd-socket-proxyd</command>
  56     are support for socket activation with
  57     <literal>Accept=false</literal> and an event-driven
  58     design that scales better with the number of
  59     connections.</para>
  60   </refsect1>
  61   <refsect1>
  62     <title>Options</title>
  63     <para>The following options are understood:</para>
  64     <variablelist>
  65       <xi:include href="standard-options.xml" xpointer="help" />
  66       <xi:include href="standard-options.xml" xpointer="version" />
  67       <varlistentry>
  68         <term><option>--connections-max=</option></term>
  69         <term><option>-c</option></term>
  70
  71         <listitem><para>Sets the maximum number of simultaneous connections, defaults to 256.
  72         If the limit of concurrent connections is reached further connections will be refused.</para></listitem>
  73       </varlistentry>
  74     </variablelist>
  75   </refsect1>
  76   <refsect1>
  77     <title>Exit status</title>
  78     <para>On success, 0 is returned, a non-zero failure
  79     code otherwise.</para>
  80   </refsect1>
  81   <refsect1>
  82     <title>Examples</title>
  83     <refsect2>
  84       <title>Simple Example</title>
  85       <para>Use two services with a dependency and no namespace
  86       isolation.</para>
  87       <example>
  88         <title>proxy-to-nginx.socket</title>
  89         <programlisting><![CDATA[[Socket]
  90 ListenStream=80
  91
  92 [Install]
  93 WantedBy=sockets.target]]></programlisting>
  94       </example>
  95       <example>
  96         <title>proxy-to-nginx.service</title>
  97         <programlisting><![CDATA[[Unit]
  98 Requires=nginx.service
  99 After=nginx.service
 100 Requires=proxy-to-nginx.socket
 101 After=proxy-to-nginx.socket
 102
 103 [Service]
 104 ExecStart=/usr/lib/systemd/systemd-socket-proxyd /run/nginx/socket
 105 PrivateTmp=yes
 106 PrivateNetwork=yes]]></programlisting>
 107       </example>
 108       <example>
 109         <title>nginx.conf</title>
 110         <programlisting>
 111 <![CDATA[[…]
 112 server {
 113     listen       unix:/run/nginx/socket;
 114     […]]]>
 115 </programlisting>
 116       </example>
 117       <example>
 118         <title>Enabling the proxy</title>
 119         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 120 $ curl http://localhost:80/]]></programlisting>
 121       </example>
 122     </refsect2>
 123     <refsect2>
 124       <title>Namespace Example</title>
 125       <para>Similar as above, but runs the socket proxy and the main
 126       service in the same private namespace, assuming that
 127       <filename>nginx.service</filename> has
 128       <varname>PrivateTmp=</varname> and
 129       <varname>PrivateNetwork=</varname> set, too.</para>
 130       <example>
 131         <title>proxy-to-nginx.socket</title>
 132         <programlisting><![CDATA[[Socket]
 133 ListenStream=80
 134
 135 [Install]
 136 WantedBy=sockets.target]]></programlisting>
 137       </example>
 138       <example>
 139         <title>proxy-to-nginx.service</title>
 140         <programlisting><![CDATA[[Unit]
 141 Requires=nginx.service
 142 After=nginx.service
 143 Requires=proxy-to-nginx.socket
 144 After=proxy-to-nginx.socket
 145 JoinsNamespaceOf=nginx.service
 146
 147 [Service]
 148 ExecStart=/usr/lib/systemd/systemd-socket-proxyd 127.0.0.1:8080
 149 PrivateTmp=yes
 150 PrivateNetwork=yes]]></programlisting>
 151       </example>
 152       <example>
 153         <title>nginx.conf</title>
 154         <programlisting><![CDATA[[…]
 155 server {
 156     listen       8080;
 157     […]]]></programlisting>
 158       </example>
 159       <example>
 160         <title>Enabling the proxy</title>
 161         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 162 $ curl http://localhost:80/]]></programlisting>
 163       </example>
 164     </refsect2>
 165   </refsect1>
 166   <refsect1>
 167     <title>See Also</title>
 168     <para>
 169       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 170       <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 171       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 172       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 173       <citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 174       <citerefentry project='die-net'><refentrytitle>nginx</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 175       <citerefentry project='die-net'><refentrytitle>curl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 176     </para>
 177   </refsect1>
 178 </refentry>