<?xml version="1.0"?>

<!--
  Copyright (C) Nginx, Inc.
  -->

<!DOCTYPE module SYSTEM "../../../../dtd/module.dtd">

<module name="Module ngx_stream_mqtt_preread_module"
        link="/en/docs/http/ngx_stream_mqtt_preread_module.html"
        lang="en"
        rev="1">

<section id="summary">

<para>
The <literal>ngx_stream_mqtt_preread_module</literal> module (1.23.4) allows
extracting information from the CONNECT message
of the Message Queuing Telemetry Transport protocol (MQTT) versions
<link url="https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/mqtt-v3.1.1.html">3.1.1</link>
and
<link url="https://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html">5.0</link>,
for example, a username or a client ID.
</para>

<para>
<note>
This module is available as part of our
<commercial_version>commercial subscription</commercial_version>.
</note>
</para>

</section>


<section id="example" name="Example Configuration">

<para>
<example>
mqtt_preread on;
return       $mqtt_preread_clientid;
</example>
</para>

</section>


<section id="directives" name="Directives">

<directive name="mqtt_preread">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>stream</context>
<context>server</context>

<para>
Enables extracting information from the MQTT CONNECT message at
the <link doc="stream_processing.xml" id="preread_phase">preread</link> phase.
</para>

</directive>

</section>


<section id="variables" name="Embedded Variables">

<para>
<list type="tag">

<tag-name id="var_mqtt_preread_clientid"><var>$mqtt_preread_clientid</var></tag-name>
<tag-desc>
the <literal>clientid</literal> value from the CONNECT message
</tag-desc>

<tag-name id="var_mqtt_preread_username"><var>$mqtt_preread_username</var></tag-name>
<tag-desc>
the <literal>username</literal> value from the CONNECT message
</tag-desc>

</list>
</para>

</section>

</module>