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comparison xml/en/docs/http/ngx_http_limit_req_module.xml @ 529:d477ae38c0bd

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Clarified on what this module actually limits.
author Ruslan Ermilov <ru@nginx.com>
date Wed, 06 Jun 2012 14:17:28 +0000
parents 0e55c9a48da9
children ebcb351d9eb3
comparison
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528:85bbe7a5f393 529:d477ae38c0bd
8 8
9 <section id="summary"> 9 <section id="summary">
10 10
11 <para> 11 <para>
12 The <literal>ngx_http_limit_req_module</literal> module (0.7.21) allows 12 The <literal>ngx_http_limit_req_module</literal> module (0.7.21) allows
13 to limit the number 13 to limit the request processing rate per defined key,
14 of requests per defined key, in particular, the number of requests 14 in particular, the processing rate of requests coming
15 from a single IP address. 15 from a single IP address.
16 The limitation is done using the “leaky bucket” method. 16 The limitation is done using the “leaky bucket” method.
17 </para> 17 </para>
18 18
19 </section> 19 </section>
58 If the rate of requests exceeds the rate configured for a zone, 58 If the rate of requests exceeds the rate configured for a zone,
59 request processing is delayed such as that they are processed 59 request processing is delayed such as that they are processed
60 at a defined rate. 60 at a defined rate.
61 Excessive requests are delayed until their number exceeds the 61 Excessive requests are delayed until their number exceeds the
62 defined number of bursts. 62 defined number of bursts.
63 In this case, the request is terminated with an error 63 When exceeded, the request is terminated with an error
64 <http-status code="503" text="Service Temporarily Unavailable"/>. 64 <http-status code="503" text="Service Temporarily Unavailable"/>.
65 By default, the number of bursts is equal to zero. 65 By default, the number of bursts is equal to zero.
66 For example, the directives 66 For example, the directives
67 <example> 67 <example>
68 limit_req_zone $binary_remote_addr zone=one:10m rate=1r/s; 68 limit_req_zone $binary_remote_addr zone=one:10m rate=1r/s;
98 <context>server</context> 98 <context>server</context>
99 <context>location</context> 99 <context>location</context>
100 <appeared-in>0.8.18</appeared-in> 100 <appeared-in>0.8.18</appeared-in>
101 101
102 <para> 102 <para>
103 Sets the desired logging level for cases when the server limits 103 Sets the desired logging level
104 the number of requests, or delays request processing. 104 for cases when the server refuses to process requests
105 Delays are logged with the level one less than limits; for example, 105 due to rate being exceeded,
106 or delays request processing.
107 Delays are logged with the level one less than refusals; for example,
106 if “<literal>limit_req_log_level notice</literal>” is specified, 108 if “<literal>limit_req_log_level notice</literal>” is specified,
107 delays are logged with the <literal>info</literal> level. 109 delays are logged with the <literal>info</literal> level.
108 </para> 110 </para>
109 111
110 </directive> 112 </directive>
118 <default/> 120 <default/>
119 <context>http</context> 121 <context>http</context>
120 122
121 <para> 123 <para>
122 Sets the parameters for a zone that keeps states for various keys. 124 Sets the parameters for a zone that keeps states for various keys.
123 This state stores the current number of requests in particular. 125 The state stores the current number of excessive requests in particular.
124 The key is any non-empty value of the specified variable 126 The key is any non-empty value of the specified variable
125 (empty values are not accounted). 127 (empty values are not accounted).
126 Example usage: 128 Example usage:
127 <example> 129 <example>
128 limit_req_zone $binary_remote_addr zone=one:10m rate=1r/s; 130 limit_req_zone $binary_remote_addr zone=one:10m rate=1r/s;
129 </example> 131 </example>
130 </para> 132 </para>
131 133
132 <para> 134 <para>
133 Here, the states are kept in a 10 megabyte zone “one”, and an 135 Here, the states are kept in a 10 megabyte zone “one”, and an
134 average rate of requests for this zone cannot exceed 136 average request processing rate for this zone cannot exceed
135 1 request per second. 137 1 request per second.
136 </para> 138 </para>
137 139
138 <para> 140 <para>
139 An IP address of the client serves as a key. 141 An IP address of the client serves as a key.