man/systemd-socket-proxyd.xml

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  23 <refentry id="systemd-socket-proxyd"
  24     xmlns:xi="http://www.w3.org/2001/XInclude">
  25
  26   <refentryinfo>
  27     <title>systemd-socket-proxyd</title>
  28     <productname>systemd</productname>
  29     <authorgroup>
  30       <author>
  31         <contrib>Developer</contrib>
  32         <firstname>David</firstname>
  33         <surname>Strauss</surname>
  34         <email>david@davidstrauss.net</email>
  35       </author>
  36     </authorgroup>
  37   </refentryinfo>
  38   <refmeta>
  39     <refentrytitle>systemd-socket-proxyd</refentrytitle>
  40     <manvolnum>8</manvolnum>
  41   </refmeta>
  42   <refnamediv>
  43     <refname>systemd-socket-proxyd</refname>
  44     <refpurpose>Bidirectionally proxy local sockets to another (possibly remote) socket.</refpurpose>
  45   </refnamediv>
  46   <refsynopsisdiv>
  47     <cmdsynopsis>
  48       <command>systemd-socket-proxyd</command>
  49       <arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg>
  50       <arg choice="plain"><replaceable>HOST</replaceable>:<replaceable>PORT</replaceable></arg>
  51     </cmdsynopsis>
  52     <cmdsynopsis>
  53       <command>systemd-socket-proxyd</command>
  54       <arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg>
  55       <arg choice="plain"><replaceable>UNIX-DOMAIN-SOCKET-PATH</replaceable>
  56       </arg>
  57     </cmdsynopsis>
  58   </refsynopsisdiv>
  59   <refsect1>
  60     <title>Description</title>
  61     <para>
  62     <command>systemd-socket-proxyd</command> is a generic
  63     socket-activated network socket forwarder proxy daemon for IPv4,
  64     IPv6 and UNIX stream sockets. It may be used to bi-directionally
  65     forward traffic from a local listening socket to a local or remote
  66     destination socket.</para>
  67
  68     <para>One use of this tool is to provide socket activation support
  69     for services that do not natively support socket activation. On
  70     behalf of the service to activate, the proxy inherits the socket
  71     from systemd, accepts each client connection, opens a connection
  72     to a configured server for each client, and then bidirectionally
  73     forwards data between the two.</para>
  74     <para>This utility's behavior is similar to
  75     <citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
  76     The main differences for <command>systemd-socket-proxyd</command>
  77     are support for socket activation with
  78     <literal>Accept=false</literal> and an event-driven
  79     design that scales better with the number of
  80     connections.</para>
  81   </refsect1>
  82   <refsect1>
  83     <title>Options</title>
  84     <para>The following options are understood:</para>
  85     <variablelist>
  86       <xi:include href="standard-options.xml" xpointer="help" />
  87       <xi:include href="standard-options.xml" xpointer="version" />
  88       <varlistentry>
  89         <term><option>--max-connections=</option></term>
  90         <term><option>-c</option></term>
  91
  92         <listitem><para>Sets the maximum number of simultaneous connections, defaults to 256.
  93         If the limit of concurrent connections is reached further connections will be refused.</para></listitem>
  94       </varlistentry>
  95     </variablelist>
  96   </refsect1>
  97   <refsect1>
  98     <title>Exit status</title>
  99     <para>On success, 0 is returned, a non-zero failure
 100     code otherwise.</para>
 101   </refsect1>
 102   <refsect1>
 103     <title>Examples</title>
 104     <refsect2>
 105       <title>Simple Example</title>
 106       <para>Use two services with a dependency and no namespace
 107       isolation.</para>
 108       <example>
 109         <title>proxy-to-nginx.socket</title>
 110         <programlisting><![CDATA[[Socket]
 111 ListenStream=80
 112
 113 [Install]
 114 WantedBy=sockets.target]]></programlisting>
 115       </example>
 116       <example>
 117         <title>proxy-to-nginx.service</title>
 118         <programlisting><![CDATA[[Unit]
 119 Requires=nginx.service
 120 After=nginx.service
 121
 122 [Service]
 123 ExecStart=/usr/lib/systemd/systemd-socket-proxyd /tmp/nginx.sock
 124 PrivateTmp=yes
 125 PrivateNetwork=yes]]></programlisting>
 126       </example>
 127       <example>
 128         <title>nginx.conf</title>
 129         <programlisting>
 130 <![CDATA[[…]
 131 server {
 132     listen       unix:/tmp/nginx.sock;
 133     […]]]>
 134 </programlisting>
 135       </example>
 136       <example>
 137         <title>Enabling the proxy</title>
 138         <programlisting><![CDATA[# systemctl enable proxy-to-nginx.socket
 139 # systemctl start proxy-to-nginx.socket
 140 $ curl http://localhost:80/]]></programlisting>
 141       </example>
 142     </refsect2>
 143     <refsect2>
 144       <title>Namespace Example</title>
 145       <para>Similar as above, but runs the socket proxy and the main
 146       service in the same private namespace, assuming that
 147       <filename>nginx.service</filename> has
 148       <varname>PrivateTmp=</varname> and
 149       <varname>PrivateNetwork=</varname> set, too.</para>
 150       <example>
 151         <title>proxy-to-nginx.socket</title>
 152         <programlisting><![CDATA[[Socket]
 153 ListenStream=80
 154
 155 [Install]
 156 WantedBy=sockets.target]]></programlisting>
 157       </example>
 158       <example>
 159         <title>proxy-to-nginx.service</title>
 160         <programlisting><![CDATA[[Unit]
 161 Requires=nginx.service
 162 After=nginx.service
 163 JoinsNamespaceOf=nginx.service
 164
 165 [Service]
 166 ExecStart=/usr/lib/systemd/systemd-socket-proxyd 127.0.0.1:8080
 167 PrivateTmp=yes
 168 PrivateNetwork=yes]]></programlisting>
 169       </example>
 170       <example>
 171         <title>nginx.conf</title>
 172         <programlisting><![CDATA[[…]
 173 server {
 174     listen       8080;
 175     […]]]></programlisting>
 176       </example>
 177       <example>
 178         <title>Enabling the proxy</title>
 179         <programlisting><![CDATA[# systemctl enable proxy-to-nginx.socket
 180 # systemctl start proxy-to-nginx.socket
 181 $ curl http://localhost:80/]]></programlisting>
 182       </example>
 183     </refsect2>
 184   </refsect1>
 185   <refsect1>
 186     <title>See Also</title>
 187     <para>
 188       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 189       <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 190       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 191       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 192       <citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 193       <citerefentry project='die-net'><refentrytitle>nginx</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 194       <citerefentry project='die-net'><refentrytitle>curl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 195     </para>
 196   </refsect1>
 197 </refentry>