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view xml/en/docs/http/ngx_http_limit_conn_module.xml @ 572:17ceffcc7ffb
Brought the ngx_http_map_module documentation up to date.
author | Ruslan Ermilov <ru@nginx.com> |
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date | Thu, 05 Jul 2012 13:15:08 +0000 |
parents | bef9e1a2e3c8 |
children | ebcb351d9eb3 |
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<?xml version="1.0"?> <!DOCTYPE module SYSTEM "../../../../dtd/module.dtd"> <module name="Module ngx_http_limit_conn_module" link="/en/docs/http/ngx_http_limit_conn_module.html" lang="en"> <section id="summary"> <para> The <literal>ngx_http_limit_conn_module</literal> module allows to limit the number of connections per defined key, in particular, the number of connections from a single IP address. </para> <para> Not all connections are counted; only those that have requests currently being processed by the server, in which request header has been fully read. </para> </section> <section id="example" name="Example Configuration"> <para> <example> http { limit_conn_zone $binary_remote_addr zone=addr:10m; ... server { ... location /download/ { limit_conn addr 1; } </example> </para> </section> <section id="directives" name="Directives"> <directive name="limit_conn"> <syntax><value>zone</value> <value>number</value></syntax> <default/> <context>http</context> <context>server</context> <context>location</context> <para> Sets the maximum allowed number of connections for a given key value. When this limit is exceeded, the server will return error <http-status code="503" text="Service Temporarily Unavailable"/> in reply to a request. For example, the directives <example> limit_conn_zone $binary_remote_addr zone=addr:10m; server { location /download/ { limit_conn addr 1; } </example> allow for only a single connection at a time, per unique IP address. </para> <para> When several <literal>limit_conn</literal> directives are specified, any configured limit will apply. For example, the following configuration will limit the number of connections to the server per client IP and at the same time will limit the total number of connections to the virtual host: <example> limit_conn_zone $binary_remote_addr zone=perip:10m; limit_conn_zone $server_name zone=perserver:10m; server { ... limit_conn perip 10; limit_conn perserver 100; } </example> </para> <para> These directives are inherited from the previous level if and only if there are no <literal>limit_conn</literal> directives on the current level. </para> </directive> <directive name="limit_conn_log_level"> <syntax> <literal>info</literal> | <literal>notice</literal> | <literal>warn</literal> | <literal>error</literal></syntax> <default>error</default> <context>http</context> <context>server</context> <context>location</context> <appeared-in>0.8.18</appeared-in> <para> Sets the desired logging level for cases when the server limits the number of connections. </para> </directive> <directive name="limit_conn_zone"> <syntax> <value>$variable</value> <literal>zone</literal>=<value>name</value>:<value>size</value></syntax> <default/> <context>http</context> <para> Sets the parameters for a zone that keeps states for various keys. This state stores the current number of connections in particular. The key is any non-empty value of the specified variable (empty values are not accounted). Example usage: <example> limit_conn_zone $binary_remote_addr zone=addr:10m; </example> Here, an IP address of the client serves as a key. Note that instead of <var>$remote_addr</var>, the <var>$binary_remote_addr</var> variable is used here. The length of the <var>$remote_addr</var> variable's value can range from 7 to 15 bytes, and the stored state occupies either 32 or 64 bytes of memory on 32-bit platforms, and always 64 bytes on 64-bit platforms. The length of the <var>$binary_remote_addr</var> variable's value is always 4 bytes, and the stored state always occupies 32 bytes on 32-bit platforms, and 64 bytes on 64-bit platforms. One megabyte zone can keep about 32 thousand 32-bit states, and about 16 thousand 64-byte states. If the storage for a zone is exhausted, the server will return error <http-status code="503" text="Service Temporarily Unavailable"/> to all further requests. </para> </directive> <directive name="limit_zone"> <syntax> <value>name</value> <value>$variable</value> <value>size</value></syntax> <default/> <context>http</context> <para> This directive is made obsolete in version 1.1.8, an equivalent <link id="limit_conn_zone"/> directive with a changed syntax should be used instead: <note> <literal>limit_conn_zone</literal> <value>$variable</value> <literal>zone</literal>=<value>name</value>:<value>size</value>; </note> </para> </directive> </section> </module>