man/systemd-socket-proxyd.xml

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   8 <refentry id="systemd-socket-proxyd"
   9     xmlns:xi="http://www.w3.org/2001/XInclude">
  10
  11   <refentryinfo>
  12     <title>systemd-socket-proxyd</title>
  13     <productname>systemd</productname>
  14   </refentryinfo>
  15   <refmeta>
  16     <refentrytitle>systemd-socket-proxyd</refentrytitle>
  17     <manvolnum>8</manvolnum>
  18   </refmeta>
  19   <refnamediv>
  20     <refname>systemd-socket-proxyd</refname>
  21     <refpurpose>Bidirectionally proxy local sockets to another (possibly remote) socket.</refpurpose>
  22   </refnamediv>
  23   <refsynopsisdiv>
  24     <cmdsynopsis>
  25       <command>systemd-socket-proxyd</command>
  26       <arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg>
  27       <arg choice="plain"><replaceable>HOST</replaceable>:<replaceable>PORT</replaceable></arg>
  28     </cmdsynopsis>
  29     <cmdsynopsis>
  30       <command>systemd-socket-proxyd</command>
  31       <arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg>
  32       <arg choice="plain"><replaceable>UNIX-DOMAIN-SOCKET-PATH</replaceable>
  33       </arg>
  34     </cmdsynopsis>
  35   </refsynopsisdiv>
  36   <refsect1>
  37     <title>Description</title>
  38     <para>
  39     <command>systemd-socket-proxyd</command> is a generic
  40     socket-activated network socket forwarder proxy daemon for IPv4,
  41     IPv6 and UNIX stream sockets. It may be used to bi-directionally
  42     forward traffic from a local listening socket to a local or remote
  43     destination socket.</para>
  44
  45     <para>One use of this tool is to provide socket activation support
  46     for services that do not natively support socket activation. On
  47     behalf of the service to activate, the proxy inherits the socket
  48     from systemd, accepts each client connection, opens a connection
  49     to a configured server for each client, and then bidirectionally
  50     forwards data between the two.</para>
  51     <para>This utility's behavior is similar to
  52     <citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
  53     The main differences for <command>systemd-socket-proxyd</command>
  54     are support for socket activation with
  55     <literal>Accept=no</literal> and an event-driven
  56     design that scales better with the number of
  57     connections.</para>
  58   </refsect1>
  59   <refsect1>
  60     <title>Options</title>
  61     <para>The following options are understood:</para>
  62     <variablelist>
  63       <xi:include href="standard-options.xml" xpointer="help" />
  64       <xi:include href="standard-options.xml" xpointer="version" />
  65       <varlistentry>
  66         <term><option>--connections-max=</option></term>
  67         <term><option>-c</option></term>
  68
  69         <listitem><para>Sets the maximum number of simultaneous connections, defaults to 256.
  70         If the limit of concurrent connections is reached further connections will be refused.</para></listitem>
  71       </varlistentry>
  72     </variablelist>
  73   </refsect1>
  74   <refsect1>
  75     <title>Exit status</title>
  76     <para>On success, 0 is returned, a non-zero failure
  77     code otherwise.</para>
  78   </refsect1>
  79   <refsect1>
  80     <title>Examples</title>
  81     <refsect2>
  82       <title>Simple Example</title>
  83       <para>Use two services with a dependency and no namespace
  84       isolation.</para>
  85       <example>
  86         <title>proxy-to-nginx.socket</title>
  87         <programlisting><![CDATA[[Socket]
  88 ListenStream=80
  89
  90 [Install]
  91 WantedBy=sockets.target]]></programlisting>
  92       </example>
  93       <example>
  94         <title>proxy-to-nginx.service</title>
  95         <programlisting><![CDATA[[Unit]
  96 Requires=nginx.service
  97 After=nginx.service
  98 Requires=proxy-to-nginx.socket
  99 After=proxy-to-nginx.socket
 100
 101 [Service]
 102 ExecStart=/usr/lib/systemd/systemd-socket-proxyd /run/nginx/socket
 103 PrivateTmp=yes
 104 PrivateNetwork=yes]]></programlisting>
 105       </example>
 106       <example>
 107         <title>nginx.conf</title>
 108         <programlisting>
 109 <![CDATA[[…]
 110 server {
 111     listen       unix:/run/nginx/socket;
 112     […]]]>
 113 </programlisting>
 114       </example>
 115       <example>
 116         <title>Enabling the proxy</title>
 117         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 118 $ curl http://localhost:80/]]></programlisting>
 119       </example>
 120     </refsect2>
 121     <refsect2>
 122       <title>Namespace Example</title>
 123       <para>Similar as above, but runs the socket proxy and the main
 124       service in the same private namespace, assuming that
 125       <filename>nginx.service</filename> has
 126       <varname>PrivateTmp=</varname> and
 127       <varname>PrivateNetwork=</varname> set, too.</para>
 128       <example>
 129         <title>proxy-to-nginx.socket</title>
 130         <programlisting><![CDATA[[Socket]
 131 ListenStream=80
 132
 133 [Install]
 134 WantedBy=sockets.target]]></programlisting>
 135       </example>
 136       <example>
 137         <title>proxy-to-nginx.service</title>
 138         <programlisting><![CDATA[[Unit]
 139 Requires=nginx.service
 140 After=nginx.service
 141 Requires=proxy-to-nginx.socket
 142 After=proxy-to-nginx.socket
 143 JoinsNamespaceOf=nginx.service
 144
 145 [Service]
 146 ExecStart=/usr/lib/systemd/systemd-socket-proxyd 127.0.0.1:8080
 147 PrivateTmp=yes
 148 PrivateNetwork=yes]]></programlisting>
 149       </example>
 150       <example>
 151         <title>nginx.conf</title>
 152         <programlisting><![CDATA[[…]
 153 server {
 154     listen       8080;
 155     […]]]></programlisting>
 156       </example>
 157       <example>
 158         <title>Enabling the proxy</title>
 159         <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket
 160 $ curl http://localhost:80/]]></programlisting>
 161       </example>
 162     </refsect2>
 163   </refsect1>
 164   <refsect1>
 165     <title>See Also</title>
 166     <para>
 167       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 168       <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 169       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 170       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 171       <citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 172       <citerefentry project='die-net'><refentrytitle>nginx</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 173       <citerefentry project='die-net'><refentrytitle>curl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 174     </para>
 175   </refsect1>
 176 </refentry>