3802a3d3d7af51ddff31943d5514382f01265770Lennart Poettering<?xml version="1.0"?>

12b42c76672a66c2d4ea7212c14f8f1b5a62b78dTom Gundersen<!DOCTYPE modulesynopsis SYSTEM "/style/modulesynopsis.dtd">

c91faef3b3facfdf13282aee957af25dd555890bLennart Poettering<?xml-stylesheet type="text/xsl" href="/style/manual.en.xsl"?>

c91faef3b3facfdf13282aee957af25dd555890bLennart Poettering

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<modulesynopsis metafile="mod_cache.xml.meta">

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<name>mod_cache</name>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<description>Content cache keyed to URIs.</description>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<status>Extension</status>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<sourcefile>mod_cache.c</sourcefile>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<identifier>cache_module</identifier>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<summary>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <note type="warning">This module should be used with care and

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek can be used to circumvent <directive

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek module="mod_authz_host">Allow</directive> and <directive

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek module="mod_authz_host">Deny</directive> directives. You

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek should not enable caching for any content to which you wish

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek to limit access by client host name, address or environment

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek variable.</note>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p><module>mod_cache</module> implements an <a

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek href="http://www.ietf.org/rfc/rfc2616.txt">RFC 2616</a> compliant HTTP

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek content cache that can be used to cache either local or proxied content.

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <module>mod_cache</module> requires the services of one or more storage

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek management modules. Two storage management modules are included in

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek the base Apache distribution:</p>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <dl>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <dt><module>mod_disk_cache</module></dt>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <dd>implements a disk based storage manager.</dd>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <dt><module>mod_mem_cache</module></dt>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <dd>implements a memory based storage manager.

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <module>mod_mem_cache</module> can be configured to operate in two

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek modes: caching open file descriptors or caching objects in heap storage.

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <module>mod_mem_cache</module> can be used to cache locally generated content

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek or to cache backend server content for <module>mod_proxy</module> when

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek configured using <directive module="mod_proxy">ProxyPass</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek (aka <dfn>reverse proxy</dfn>)</dd>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </dl>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

3ba3a79df4ae094d1008c04a9af8d1ff970124c4Zbigniew Jędrzejewski-Szmek <p>Content is stored in and retrieved from the cache using URI based keys. Content with

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek access protection is not cached.</p>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>Further details, discussion, and examples, are provided in the

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <a href="/caching.html">Caching Guide</a>.</p>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek</summary>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<seealso><a href="/caching.html">Caching Guide</a></seealso>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<section id="related"><title>Related Modules and Directives</title>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <related>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <modulelist>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <module>mod_disk_cache</module>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <module>mod_mem_cache</module>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </modulelist>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directivelist>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_disk_cache">CacheRoot</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_disk_cache">CacheDirLevels</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_disk_cache">CacheDirLength</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_disk_cache">CacheMinFileSize</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_disk_cache">CacheMaxFileSize</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_mem_cache">MCacheSize</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_mem_cache">MCacheMaxObjectCount</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_mem_cache">MCacheMinObjectSize</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_mem_cache">MCacheMaxObjectSize</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_mem_cache">MCacheRemovalAlgorithm</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <directive module="mod_mem_cache">MCacheMaxStreamingBuffer</directive>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </directivelist>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </related>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek</section>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<section id="sampleconf"><title>Sample Configuration</title>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <example><title>Sample httpd.conf</title>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek #<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek # Sample Cache Configuration<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek #<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek LoadModule cache_module modules/mod_cache.so<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek &lt;IfModule mod_cache.c&gt;<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <indent>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek #LoadModule disk_cache_module modules/mod_disk_cache.so<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek # If you want to use mod_disk_cache instead of mod_mem_cache,<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek # uncomment the line above and comment out the LoadModule line below.<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek &lt;IfModule mod_disk_cache.c&gt;<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <indent>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek CacheRoot c:/cacheroot<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek CacheEnable disk /<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek CacheDirLevels 5<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek CacheDirLength 3<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </indent>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek &lt;/IfModule&gt; <br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek LoadModule mem_cache_module modules/mod_mem_cache.so<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek &lt;IfModule mod_mem_cache.c&gt;<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <indent>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek CacheEnable mem /<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek MCacheSize 4096<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek MCacheMaxObjectCount 100<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek MCacheMinObjectSize 1<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek MCacheMaxObjectSize 2048<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </indent>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek &lt;/IfModule&gt;<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek # When acting as a proxy, don't cache the list of security updates<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek CacheDisable http://security.update.server/update-list/<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </indent>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek &lt;/IfModule&gt;

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </example>

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek</section>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<directivesynopsis>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<name>CacheEnable</name>

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek<description>Enable caching of specified URLs using a specified storage

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmekmanager</description>

71418295125c542d3edd1e7251bb0701ef1af89bZbigniew Jędrzejewski-Szmek<syntax>CacheEnable <var>cache_type</var> <var>url-string</var></syntax>

71418295125c542d3edd1e7251bb0701ef1af89bZbigniew Jędrzejewski-Szmek<contextlist><context>server config</context><context>virtual host</context>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek</contextlist>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

71418295125c542d3edd1e7251bb0701ef1af89bZbigniew Jędrzejewski-Szmek<usage>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>The <directive>CacheEnable</directive> directive instructs

71418295125c542d3edd1e7251bb0701ef1af89bZbigniew Jędrzejewski-Szmek <module>mod_cache</module> to cache urls at or below

71418295125c542d3edd1e7251bb0701ef1af89bZbigniew Jędrzejewski-Szmek <var>url-string</var>. The cache storage manager is specified with the

71418295125c542d3edd1e7251bb0701ef1af89bZbigniew Jędrzejewski-Szmek <var>cache_type</var> argument. <var>cache_type</var> <code> mem</code>

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek instructs <module>mod_cache</module> to use the memory based storage

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek manager implemented by <module>mod_mem_cache</module>.

b938cb902c3b5bca807a94b277672c64d6767886Jan Engelhardt <var>cache_type</var> <code>disk</code> instructs

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek <module>mod_cache</module> to use the disk based storage manager

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek implemented by <module>mod_disk_cache</module>.

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek <var>cache_type</var> <code>fd</code> instructs

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <module>mod_cache</module> to use the file descriptor cache implemented

71418295125c542d3edd1e7251bb0701ef1af89bZbigniew Jędrzejewski-Szmek by <module>mod_mem_cache</module>.</p>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>In the event that the URL space overlaps between different

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek <directive>CacheEnable</directive> directives (as in the example below),

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek each possible storage manager will be run until the first one that

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek actually processes the request. The order in which the storage managers are

7284335adbb8cb2bc9c11f9e102906da1bf71145Zbigniew Jędrzejewski-Szmek run is determined by the order of the <directive>CacheEnable</directive>

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek directives in the configuration file.</p>

7284335adbb8cb2bc9c11f9e102906da1bf71145Zbigniew Jędrzejewski-Szmek

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <example>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek CacheEnable mem /manual<br />

c91faef3b3facfdf13282aee957af25dd555890bLennart Poettering CacheEnable fd /images<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek CacheEnable disk /<br />

7284335adbb8cb2bc9c11f9e102906da1bf71145Zbigniew Jędrzejewski-Szmek </example>

7284335adbb8cb2bc9c11f9e102906da1bf71145Zbigniew Jędrzejewski-Szmek

7284335adbb8cb2bc9c11f9e102906da1bf71145Zbigniew Jędrzejewski-Szmek <p>When acting as a forward proxy server, <var>url-string</var> can

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek also be used to specify remote sites and proxy protocols which

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek caching should be enabled for.</p>

b938cb902c3b5bca807a94b277672c64d6767886Jan Engelhardt

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek <example>

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek # Cache proxied url's<br />

9407bc2d03b6405754807b6f38c8ca95b4fc1f40Zbigniew Jędrzejewski-Szmek CacheEnable disk /<br /><br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek # Cache FTP-proxied url's<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek CacheEnable disk ftp://<br /><br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek # Cache content from www.apache.org<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek CacheEnable disk http://www.apache.org/<br />

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </example>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek</usage>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek</directivesynopsis>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek

3ba3a79df4ae094d1008c04a9af8d1ff970124c4Zbigniew Jędrzejewski-Szmek<directivesynopsis>

3ba3a79df4ae094d1008c04a9af8d1ff970124c4Zbigniew Jędrzejewski-Szmek<name>CacheDisable</name>

3ba3a79df4ae094d1008c04a9af8d1ff970124c4Zbigniew Jędrzejewski-Szmek<description>Disable caching of specified URLs</description>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<syntax>CacheDisable <var> url-string</var></syntax>

798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<contextlist><context>server config</context><context>virtual host</context>

c91faef3b3facfdf13282aee957af25dd555890bLennart Poettering</contextlist>

c91faef3b3facfdf13282aee957af25dd555890bLennart Poettering

<usage>

<p>The <directive>CacheDisable</directive> directive instructs

<module>mod_cache</module> to <em>not</em> cache urls at or below

<var>url-string</var>.</p>

<example><title>Example</title>

CacheDisable /local_files

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>CacheMaxExpire</name>

<description>The maximum time in seconds to cache a document</description>

<syntax>CacheMaxExpire <var>seconds</var></syntax>

<default>CacheMaxExpire 86400 (one day)</default>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>The <directive>CacheMaxExpire</directive> directive specifies the maximum number of

seconds for which cachable HTTP documents will be retained without checking the origin

server. Thus, documents will be out of date at most this number of seconds. This maximum

value is enforced even if an expiry date was supplied with the document.</p>

<example>

CacheMaxExpire 604800

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>CacheMinExpire</name>

<description>The minimum time in seconds to cache a document</description>

<syntax>CacheMinExpire <var>seconds</var></syntax>

<default>CacheMinExpire 0</default>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>The <directive>CacheMinExpire</directive> directive specifies the minimum number of

seconds for which cachable HTTP documents will be retained without checking the origin

server. This is only used if no valid expire time was supplied with the document.</p>

<example>

CacheMinExpire 3600

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>CacheDefaultExpire</name>

<description>The default duration to cache a document when no expiry date is specified.</description>

<syntax>CacheDefaultExpire <var>seconds</var></syntax>

<default>CacheDefaultExpire 3600 (one hour)</default>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>The <directive>CacheDefaultExpire</directive> directive specifies a default time,

in seconds, to cache a document if neither an expiry date nor last-modified date are provided

with the document. The value specified with the <directive>CacheMaxExpire</directive>

directive does <em>not</em> override this setting.</p>

<example>

CacheDefaultExpire 86400

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>CacheIgnoreNoLastMod</name>

<description>Ignore the fact that a response has no Last Modified

header.</description>

<syntax>CacheIgnoreNoLastMod On|Off</syntax>

<default>CacheIgnoreNoLastMod Off</default>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>Ordinarily, documents without a last-modified date are not cached.

Under some circumstances the last-modified date is removed (during

<module>mod_include</module> processing for example) or not provided

at all. The <directive>CacheIgnoreNoLastMod</directive> directive

provides a way to specify that documents without last-modified dates

should be considered for caching, even without a last-modified date.

If neither a last-modified date nor an expiry date are provided with

the document then the value specified by the

<directive>CacheDefaultExpire</directive> directive will be used to

generate an expiration date.</p>

<example>

CacheIgnoreNoLastMod On

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>CacheIgnoreCacheControl</name>

<description>Ignore request to not serve cached content to client</description>

<syntax>CacheIgnoreCacheControl On|Off</syntax>

<default>CacheIgnoreCacheControl Off</default>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>Ordinarily, requests containing a Cache-Control: no-cache or

Pragma: no-cache header value will not be served from the cache. The

<directive>CacheIgnoreCacheControl</directive> directive allows this

behavior to be overridden. <directive>CacheIgnoreCacheControl</directive>

On tells the server to attempt to serve the resource from the cache even

if the request contains no-cache header values. Resources requiring

authorization will <em>never</em> be cached.</p>

<example>

CacheIgnoreCacheControl On

</example>

<note type="warning"><title>Warning:</title>

This directive will allow serving from the cache even if the client has

requested that the document not be served from the cache. This might

result in stale content being served.

</note>

</usage>

<seealso><directive module="mod_cache">CacheStorePrivate</directive></seealso>

<seealso><directive module="mod_cache">CacheStoreNoStore</directive></seealso>

</directivesynopsis>

<directivesynopsis>

<name>CacheIgnoreQueryString</name>

<description>Ignore query string when caching</description>

<syntax>CacheIgnoreQueryString On|Off</syntax>

<default>CacheIgnoreQueryString Off</default>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>Ordinarily, requests with query string parameters are cached separately

for each unique query string. This is according to RFC 2616/13.9 done only

if an expiration time is specified. The

<directive>CacheIgnoreQueryString</directive> directive tells the cache to

cache requests even if no expiration time is specified, and to reply with

a cached reply even if the query string differs. From a caching point of

view the request is treated as if having no query string when this

directive is enabled.</p>

<example>

CacheIgnoreQueryString On

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>CacheLastModifiedFactor</name>

<description>The factor used to compute an expiry date based on the

LastModified date.</description>

<syntax>CacheLastModifiedFactor <var>float</var></syntax>

<default>CacheLastModifiedFactor 0.1</default>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>In the event that a document does not provide an expiry date but does

provide a last-modified date, an expiry date can be calculated based on

the time since the document was last modified. The

<directive>CacheLastModifiedFactor</directive> directive specifies a

<var>factor</var> to be used in the generation of this expiry date

according to the following formula:

<code>expiry-period = time-since-last-modified-date * <var>factor</var>

expiry-date = current-date + expiry-period</code>

For example, if the document was last modified 10 hours ago, and

<var>factor</var> is 0.1 then the expiry-period will be set to

10*0.1 = 1 hour. If the current time was 3:00pm then the computed

expiry-date would be 3:00pm + 1hour = 4:00pm.

If the expiry-period would be longer than that set by

<directive>CacheMaxExpire</directive>, then the latter takes

precedence.</p>

<example>

CacheLastModifiedFactor 0.5

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>CacheIgnoreHeaders</name>

<description>Do not store the given HTTP header(s) in the cache.

</description>

<syntax>CacheIgnoreHeaders <var>header-string</var> [<var>header-string</var>] ...</syntax>

<default>CacheIgnoreHeaders None</default>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>According to RFC 2616, hop-by-hop HTTP headers are not stored in

the cache. The following HTTP headers are hop-by-hop headers and thus

do not get stored in the cache in <em>any</em> case regardless of the

setting of <directive>CacheIgnoreHeaders</directive>:</p>

<ul>

<li><code>Connection</code></li>

<li><code>Keep-Alive</code></li>

<li><code>Proxy-Authenticate</code></li>

<li><code>Proxy-Authorization</code></li>

<li><code>TE</code></li>

<li><code>Trailers</code></li>

<li><code>Transfer-Encoding</code></li>

<li><code>Upgrade</code></li>

</ul>

<p><directive>CacheIgnoreHeaders</directive> specifies additional HTTP

headers that should not to be stored in the cache. For example, it makes

sense in some cases to prevent cookies from being stored in the cache.</p>

<p><directive>CacheIgnoreHeaders</directive> takes a space separated list

of HTTP headers that should not be stored in the cache. If only hop-by-hop

headers not should be stored in the cache (the RFC 2616 compliant

behaviour), <directive>CacheIgnoreHeaders</directive> can be set to

<code>None</code>.</p>

<example><title>Example 1</title>

CacheIgnoreHeaders Set-Cookie

</example>

<example><title>Example 2</title>

CacheIgnoreHeaders None

</example>

<note type="warning"><title>Warning:</title>

If headers like <code>Expires</code> which are needed for proper cache

management are not stored due to a

<directive>CacheIgnoreHeaders</directive> setting, the behaviour of

mod_cache is undefined.

</note>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>CacheStorePrivate</name>

<description>Attempt to cache responses that the server has marked as private</description>

<syntax>CacheStorePrivate On|Off</syntax>

<default>CacheStorePrivate Off</default>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>Ordinarily, responses with Cache-Control: private header values will not

be stored in the cache. The <directive>CacheStorePrivate</directive>

directive allows this behavior to be overridden.

<directive>CacheStorePrivate</directive> On

tells the server to attempt to cache the resource even if it contains

private header values. Resources requiring authorization will

<em>never</em> be cached.</p>

<example>

CacheStorePrivate On

</example>

<note type="warning"><title>Warning:</title>

This directive will allow caching even if the upstream server has

requested that the resource not be cached. This directive is only

ideal for a 'private' cache.

</note>

</usage>

<seealso><directive module="mod_cache">CacheIgnoreCacheControl</directive></seealso>

<seealso><directive module="mod_cache">CacheStoreNoStore</directive></seealso>

</directivesynopsis>

<directivesynopsis>

<name>CacheStoreNoStore</name>

<description>Attempt to cache requests or responses that have been marked as no-store.</description>

<syntax>CacheStoreNoStore On|Off</syntax>

<default>CacheStoreNoStore Off</default>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<usage>

<p>Ordinarily, requests or responses with Cache-Control: no-store header

values will not be stored in the cache. The

<directive>CacheStoreNoCache</directive> directive allows this

behavior to be overridden. <directive>CacheStoreNoCache</directive> On

tells the server to attempt to cache the resource even if it contains

no-store header values. Resources requiring authorization will

<em>never</em> be cached.</p>

<example>

CacheStoreNoStore On

</example>

<note type="warning"><title>Warning:</title>

As described in RFC 2616, the no-store directive is intended to

"prevent the inadvertent release or retention of sensitive information

(for example, on backup tapes)." Enabling this option could store

sensitive information in the cache. You are hereby warned.

</note>

</usage>

<seealso><directive module="mod_cache">CacheIgnoreCacheControl</directive></seealso>

<seealso><directive module="mod_cache">CacheStorePrivate</directive></seealso>

</directivesynopsis>

</modulesynopsis>