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<?xml version="1.0"?>
<!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2013 David Strauss
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="systemd-socket-proxyd">
<refentryinfo>
<title>systemd-socket-proxyd</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>David</firstname>
<surname>Strauss</surname>
<email>david@davidstrauss.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-socket-proxyd</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-socket-proxyd</refname>
<refpurpose>Bidirectionally proxy local sockets to another (possibly remote) socket.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>systemd-socket-proxyd</command>
<arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg>
<arg choice="plain"><replaceable>HOST</replaceable>:<replaceable>PORT</replaceable></arg>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-socket-proxyd</command>
<arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg>
<arg choice="plain"><replaceable>UNIX-DOMAIN-SOCKET-PATH</replaceable>
</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>systemd-socket-proxyd</command> is a generic
socket-activated network socket forwarder proxy daemon
for IPv4, IPv6 and UNIX stream sockets. It may be used
to bi-directionally forward traffic from a local listening socket to a
local or remote destination socket.</para>
<para>One use of this tool is to provide
socket activation support for services that do not
natively support socket activation. On behalf of the
service to activate, the proxy inherits the socket
from systemd, accepts each client connection, opens a
connection to a configured server for each client, and
then bidirectionally forwards data between the
two.</para>
<para>This utility's behavior is similar to
<citerefentry><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
The main differences for <command>systemd-socket-proxyd</command>
are support for socket activation with
<literal>Accept=false</literal> and an event-driven
design that scales better with the number of
connections.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>-h</option></term>
<term><option>--help</option></term>
<listitem>
<para>Prints a short help
text and exits.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--version</option></term>
<listitem>
<para>Prints a version
string and exits.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>On success, 0 is returned, a non-zero failure
code otherwise.</para>
</refsect1>
<refsect1>
<title>Examples</title>
<refsect2>
<title>Direct-Use Example</title>
<para>Use two services with a dependency
and no namespace isolation.</para>
<example label="proxy socket unit">
<title>/etc/systemd/system/proxy-to-nginx.socket</title>
<programlisting>
<![CDATA[[Socket]
ListenStream=80
[Install]
WantedBy=sockets.target]]>
</programlisting>
</example>
<example label="proxy service unit">
<title>/etc/systemd/system/proxy-to-nginx.service</title>
<programlisting>
<![CDATA[[Unit]
After=nginx.service
Requires=nginx.service
[Service]
ExecStart=/usr/bin/systemd-socket-proxyd /tmp/nginx.sock
PrivateTmp=true
PrivateNetwork=true]]>
</programlisting>
</example>
<example label="nginx configuration">
<title>/etc/nginx/nginx.conf</title>
<programlisting>
<![CDATA[[...]
server {
listen unix:/tmp/nginx.sock;
[...]]]>
</programlisting>
</example>
<example label="commands">
<programlisting>
<![CDATA[# systemctl enable proxy-to-nginx.socket
# systemctl start proxy-to-nginx.socket
$ curl http://localhost:80/]]>
</programlisting>
</example>
</refsect2>
<refsect2>
<title>Indirect-Use Example</title>
<para>Use a shell script to isolate the
service and proxy into the same namespace.
This is particularly useful for running
TCP-only daemons without the daemon
affecting ports on regular
interfaces.</para>
<example label="combined proxy and nginx socket unit">
<title>
/etc/systemd/system/proxy-with-nginx.socket</title>
<programlisting>
<![CDATA[[Socket]
ListenStream=80
[Install]
WantedBy=sockets.target]]>
</programlisting>
</example>
<example label="combined proxy and nginx service unit">
<title>
/etc/systemd/system/proxy-with-nginx.service</title>
<programlisting>
<![CDATA[[Unit]
After=remote-fs.target nss-lookup.target
[Service]
ExecStartPre=/usr/sbin/nginx -t
ExecStart=/usr/bin/socket-proxyd-nginx.sh
PrivateTmp=true
PrivateNetwork=true]]>
</programlisting>
</example>
<example label="shell script">
<title>
/usr/bin/socket-proxyd-nginx.sh</title>
<programlisting>
<![CDATA[#!/bin/sh
/usr/sbin/nginx
while [ ! -f /tmp/nginx.pid ]
do
/usr/bin/inotifywait /tmp/nginx.pid
done
exec /usr/bin/systemd-socket-proxyd localhost 8080]]>
</programlisting>
</example>
<example label="nginx configuration">
<title>
/etc/nginx/nginx.conf</title>
<programlisting>
<![CDATA[[...]
server {
listen 8080;
listen unix:/tmp/nginx.sock;
[...]]]>
</programlisting>
</example>
<example label="commands">
<programlisting>
<![CDATA[# systemctl enable proxy-with-nginx.socket
# systemctl start proxy-with-nginx.socket
$ curl http://localhost:80/]]>
</programlisting>
</example>
</refsect2>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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