<?xml version="1.0"?>

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

<module name="Module ngx_http_memcached_module"
        link="/en/docs/http/ngx_http_memcached_module.html"
        lang="en">

<section id="summary">

<para>
The <literal>ngx_http_memcached_module</literal> module allows to obtain
responses from a memcached server.
The key is set in the <var>$memcached_key</var> variable.
A response should be put in memcached in advance via means that are
external to nginx.
</para>

</section>


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

<para>
<example>
server {
    location / {
        set            $memcached_key "$uri?$args";
        memcached_pass host:11211;
        error_page     404 502 504 = @fallback;
    }

    location @fallback {
        proxy_pass     http://backend;
    }
}
</example>
</para>

</section>


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

<directive name="memcached_buffer_size">
<syntax><value>size</value></syntax>
<default>4k|8k</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Sets <value>size</value> of the buffer used for reading a response
received from the memcached server.
A response is passed to a client synchronously, immediately as it is received.
</para>

</directive>


<directive name="memcached_connect_timeout">
<syntax><value>time</value></syntax>
<default>60s</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Defines a timeout for establishing a connection with the memcached server.
It should be noted that this timeout cannot usually exceed 75 seconds.
</para>

</directive>


<directive name="memcached_next_upstream">
<syntax>
    <literal>error</literal> |
    <literal>timeout</literal> |
    <literal>invalid_response</literal> |
    <literal>not_found</literal> |
    <literal>off</literal>
    ...</syntax>
<default>error timeout</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Specifies in which cases a request should be passed to the next server:
<list type="tag">

<tag-name><literal>error</literal></tag-name>
<tag-desc>an error occurred while establishing a connection with the
server, passing it a request, or reading the response header;</tag-desc>

<tag-name><literal>timeout</literal></tag-name>
<tag-desc>a timeout has occurred while establishing a connection with the
server, passing it a request, or reading the response header;</tag-desc>

<tag-name><literal>invalid_response</literal></tag-name>
<tag-desc>a server returned empty or invalid response;</tag-desc>

<tag-name><literal>not_found</literal></tag-name>
<tag-desc>a response was not found on the server;</tag-desc>

<tag-name><literal>off</literal></tag-name>
<tag-desc>disables passing a request to the next server.</tag-desc>

</list>
</para>

<para>
It should be understood that passing a request to the next server is
only possible if a client was not sent anything yet.
That is, if an error or a timeout occurs in the middle of
transferring a response, fixing this is impossible.
</para>

</directive>


<directive name="memcached_pass">
<syntax><value>address</value></syntax>
<default/>
<context>location</context>
<context>if in location</context>

<para>
Sets an address of the memcached server.
An address can be specified as a domain name or an address, and a port,
for example,
<example>
memcached_pass localhost:11211;
</example>
</para>

<para>
If a domain name resolves to several addresses, all of them will be
used in a round-robin fashion.
In addition, an address can be specified as a
<link doc="ngx_http_upstream_module.xml">server group</link>.
</para>

</directive>


<directive name="memcached_read_timeout">
<syntax><value>time</value></syntax>
<default>60s</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Defines a timeout for reading a response from the memcached server.
A timeout is only set between two successive read operations,
not for the transmission of the whole response.
If a memcached server does not transmit anything within this time,
a connection is closed.
</para>

</directive>


<directive name="memcached_send_timeout">
<syntax><value>time</value></syntax>
<default>60s</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Sets a timeout for transmitting a request to the memcached server.
A timeout is only set between two successive write operations,
not for the transmission of the whole request.
If a memcached server does not receive anything within this time,
a connection is closed.
</para>

</directive>

</section>

</module>