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view xml/en/docs/http/ngx_http_limit_conn_module.xml @ 2846:fdf1464e1977
Moved banner to the external file to make partial rollout possible.
An idea is to have several banners and show them with different probability
specified by split directive in the nginx.conf
author | Sergey Budnevitch <sb@waeme.net> |
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date | Tue, 10 May 2022 18:07:27 +0400 |
parents | eeed494bba51 |
children | a85e4d126bc7 |
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<?xml version="1.0"?> <!-- Copyright (C) Igor Sysoev Copyright (C) Nginx, Inc. --> <!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" rev="14"> <section id="summary"> <para> The <literal>ngx_http_limit_conn_module</literal> module is used to limit the number of connections per the defined key, in particular, the number of connections from a single IP address. </para> <para> Not all connections are counted. A connection is counted only if it has a request being processed by the server and the whole request header has already been 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 shared memory zone and the maximum allowed number of connections for a given key value. When this limit is exceeded, the server will return the <link id="limit_conn_status">error</link> 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 only one connection per an IP address at a time. <note> In HTTP/2 and SPDY, each concurrent request is considered a separate connection. </note> </para> <para> There could be several <literal>limit_conn</literal> directives. For example, the following configuration will limit the number of connections to the server per a client IP and, at the same time, the total number of connections to the virtual server: <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 configuration level if and only if there are no <literal>limit_conn</literal> directives defined on the current level. </para> </directive> <directive name="limit_conn_dry_run"> <syntax><literal>on</literal> | <literal>off</literal></syntax> <default>off</default> <context>http</context> <context>server</context> <context>location</context> <appeared-in>1.17.6</appeared-in> <para> Enables the dry run mode. In this mode, the number of connections is not limited, however, in the shared memory zone, the number of excessive connections is accounted as usual. </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_status"> <syntax><value>code</value></syntax> <default>503</default> <context>http</context> <context>server</context> <context>location</context> <appeared-in>1.3.15</appeared-in> <para> Sets the status code to return in response to rejected requests. </para> </directive> <directive name="limit_conn_zone"> <syntax> <value>key</value> <literal>zone</literal>=<value>name</value>:<value>size</value></syntax> <default/> <context>http</context> <para> Sets parameters for a shared memory zone that will keep states for various keys. In particular, the state includes the current number of connections. The <value>key</value> can contain text, variables, and their combination. Requests with an empty key value are not accounted. <note> Prior to version 1.7.6, a <value>key</value> could contain exactly one variable. </note> Usage example: <example> limit_conn_zone $binary_remote_addr zone=addr:10m; </example> Here, a client IP address serves as a key. Note that instead of <var>$remote_addr</var>, the <var>$binary_remote_addr</var> variable is used here. The <var>$remote_addr</var> variable’s size can vary from 7 to 15 bytes. The stored state occupies either 32 or 64 bytes of memory on 32-bit platforms and always 64 bytes on 64-bit platforms. The <var>$binary_remote_addr</var> variable’s size is always 4 bytes for IPv4 addresses or 16 bytes for IPv6 addresses. The stored state always occupies 32 or 64 bytes on 32-bit platforms and 64 bytes on 64-bit platforms. One megabyte zone can keep about 32 thousand 32-byte states or about 16 thousand 64-byte states. If the zone storage is exhausted, the server will return the <link id="limit_conn_status">error</link> to all further requests. </para> <para> <note> Additionally, as part of our <commercial_version>commercial subscription</commercial_version>, the <link doc="ngx_http_api_module.xml" id="http_limit_conns_">status information</link> for each such shared memory zone can be <link doc="ngx_http_api_module.xml" id="getHttpLimitConnZone">obtained</link> or <link doc="ngx_http_api_module.xml" id="deleteHttpLimitConnZoneStat">reset</link> with the <link doc="ngx_http_api_module.xml">API</link> since 1.17.7. </note> </para> </directive> <directive name="limit_zone"> <syntax> <value>name</value> <value>$variable</value> <value>size</value></syntax> <default/> <context>http</context> <para> This directive was made obsolete in version 1.1.8 and was removed in version 1.7.6. An equivalent <link id="limit_conn_zone"/> directive with a changed syntax should be used instead: <note> <literal>limit_conn_zone</literal> <value>$variable</value> <literal>zone</literal>=<value>name</value>:<value>size</value>; </note> </para> </directive> </section> <section id="variables" name="Embedded Variables"> <para> <list type="tag"> <tag-name id="var_limit_conn_status"><var>$limit_conn_status</var></tag-name> <tag-desc> keeps the result of limiting the number of connections (1.17.6): <literal>PASSED</literal>, <literal>REJECTED</literal>, or <literal>REJECTED_DRY_RUN</literal> </tag-desc> </list> </para> </section> </module>