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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 --system daemon-reload
# systemctl start proxy-to-nginx.socket
# systemctl enable 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=syslog.target 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 --system daemon-reload
# systemctl start proxy-with-nginx.socket
# systemctl enable 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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