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diff --git a/docs/manual/rewrite/advanced.html.en b/docs/manual/rewrite/advanced.html.en new file mode 100644 index 0000000..c2ad1c0 --- /dev/null +++ b/docs/manual/rewrite/advanced.html.en @@ -0,0 +1,370 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head> +<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" /> +<!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>Advanced Techniques with mod_rewrite - Apache HTTP Server Version 2.4</title> +<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> +<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> +<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" /> +<script src="../style/scripts/prettify.min.js" type="text/javascript"> +</script> + +<link href="../images/favicon.ico" rel="shortcut icon" /></head> +<body id="manual-page"><div id="page-header"> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p> +<p class="apache">Apache HTTP Server Version 2.4</p> +<img alt="" src="../images/feather.png" /></div> +<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div> +<div id="path"> +<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.4</a> > <a href="./">Rewrite</a></div><div id="page-content"><div id="preamble"><h1>Advanced Techniques with mod_rewrite</h1> +<div class="toplang"> +<p><span>Available Languages: </span><a href="../en/rewrite/advanced.html" title="English"> en </a> | +<a href="../fr/rewrite/advanced.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p> +</div> + + +<p>This document supplements the <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> +<a href="../mod/mod_rewrite.html">reference documentation</a>. It provides +a few advanced techniques using mod_rewrite.</p> + +<div class="warning">Note that many of these examples won't work unchanged in your +particular server configuration, so it's important that you understand +them, rather than merely cutting and pasting the examples into your +configuration.</div> + +</div> +<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#sharding">URL-based sharding across multiple backends</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#on-the-fly-content">On-the-fly Content-Regeneration</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#load-balancing">Load Balancing</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#structuredhomedirs">Structured Userdirs</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#redirectanchors">Redirecting Anchors</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#time-dependent">Time-Dependent Rewriting</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#setenvvars">Set Environment Variables Based On URL Parts</a></li> +</ul><h3>See also</h3><ul class="seealso"><li><a href="../mod/mod_rewrite.html">Module documentation</a></li><li><a href="intro.html">mod_rewrite introduction</a></li><li><a href="remapping.html">Redirection and remapping</a></li><li><a href="access.html">Controlling access</a></li><li><a href="vhosts.html">Virtual hosts</a></li><li><a href="proxy.html">Proxying</a></li><li><a href="rewritemap.html">Using RewriteMap</a></li><li><a href="avoid.html">When not to use mod_rewrite</a></li><li><a href="#comments_section">Comments</a></li></ul></div> +<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="sharding" id="sharding">URL-based sharding across multiple backends</a></h2> + + + + <dl> + <dt>Description:</dt> + + <dd> + <p>A common technique for distributing the burden of + server load or storage space is called "sharding". + When using this method, a front-end server will use the + url to consistently "shard" users or objects to separate + backend servers.</p> + </dd> + + <dt>Solution:</dt> + + <dd> + <p>A mapping is maintained, from users to target servers, in + external map files. They look like:</p> + +<div class="example"><p><code> +user1 physical_host_of_user1<br /> +user2 physical_host_of_user2<br /> +# ... and so on +</code></p></div> + + <p>We put this into a <code>map.users-to-hosts</code> file. The + aim is to map;</p> + +<div class="example"><p><code> +/u/user1/anypath +</code></p></div> + + <p>to</p> + +<div class="example"><p><code> +http://physical_host_of_user1/u/user/anypath +</code></p></div> + + <p>thus every URL path need not be valid on every backend physical + host. The following ruleset does this for us with the help of the map + files assuming that server0 is a default server which will be used if + a user has no entry in the map:</p> + +<pre class="prettyprint lang-config">RewriteEngine on +RewriteMap users-to-hosts "txt:/path/to/map.users-to-hosts" +RewriteRule "^/u/([^/]+)/?(.*)" "http://${users-to-hosts:$1|server0}/u/$1/$2"</pre> + + </dd> + </dl> + + <p>See the <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code> + documentation and the <a href="./rewritemap.html">RewriteMap HowTo</a> + for more discussion of the syntax of this directive.</p> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="on-the-fly-content" id="on-the-fly-content">On-the-fly Content-Regeneration</a></h2> + + + + <dl> + <dt>Description:</dt> + + <dd> + <p>We wish to dynamically generate content, but store it + statically once it is generated. This rule will check for the + existence of the static file, and if it's not there, generate + it. The static files can be removed periodically, if desired (say, + via cron) and will be regenerated on demand.</p> + </dd> + + <dt>Solution:</dt> + + <dd> + This is done via the following ruleset: + +<pre class="prettyprint lang-config"># This example is valid in per-directory context only +RewriteCond "%{REQUEST_URI}" "!-U" +RewriteRule "^(.+)\.html$" "/regenerate_page.cgi" [PT,L]</pre> + + + <p>The <code>-U</code> operator determines whether the test string + (in this case, <code>REQUEST_URI</code>) is a valid URL. It does + this via a subrequest. In the event that this subrequest fails - + that is, the requested resource doesn't exist - this rule invokes + the CGI program <code>/regenerate_page.cgi</code>, which generates + the requested resource and saves it into the document directory, so + that the next time it is requested, a static copy can be served.</p> + + <p>In this way, documents that are infrequently updated can be served in + static form. if documents need to be refreshed, they can be deleted + from the document directory, and they will then be regenerated the + next time they are requested.</p> + </dd> + </dl> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="load-balancing" id="load-balancing">Load Balancing</a></h2> + + + + <dl> + <dt>Description:</dt> + + <dd> + <p>We wish to randomly distribute load across several servers + using mod_rewrite.</p> + </dd> + + <dt>Solution:</dt> + + <dd> + <p>We'll use <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code> and a list of servers + to accomplish this.</p> + +<pre class="prettyprint lang-config">RewriteEngine on +RewriteMap lb "rnd:/path/to/serverlist.txt" +RewriteRule "^/(.*)" "http://${lb:servers}/$1" [P,L]</pre> + + +<p><code>serverlist.txt</code> will contain a list of the servers:</p> + +<div class="example"><p><code> +## serverlist.txt<br /> +<br /> +servers one.example.com|two.example.com|three.example.com<br /> +</code></p></div> + +<p>If you want one particular server to get more of the load than the +others, add it more times to the list.</p> + + </dd> + + <dt>Discussion</dt> + <dd> +<p>Apache comes with a load-balancing module - +<code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code> - which is far more flexible and +featureful than anything you can cobble together using mod_rewrite.</p> + </dd> + </dl> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="structuredhomedirs" id="structuredhomedirs">Structured Userdirs</a></h2> + + + + <dl> + <dt>Description:</dt> + + <dd> + <p>Some sites with thousands of users use a + structured homedir layout, <em>i.e.</em> each homedir is in a + subdirectory which begins (for instance) with the first + character of the username. So, <code>/~larry/anypath</code> + is <code>/home/<strong>l</strong>/larry/public_html/anypath</code> + while <code>/~waldo/anypath</code> is + <code>/home/<strong>w</strong>/waldo/public_html/anypath</code>.</p> + </dd> + + <dt>Solution:</dt> + + <dd> + <p>We use the following ruleset to expand the tilde URLs + into the above layout.</p> + +<pre class="prettyprint lang-config">RewriteEngine on +RewriteRule "^/~(<strong>([a-z])</strong>[a-z0-9]+)(.*)" "/home/<strong>$2</strong>/$1/public_html$3"</pre> + + </dd> + </dl> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="redirectanchors" id="redirectanchors">Redirecting Anchors</a></h2> + + + + <dl> + <dt>Description:</dt> + + <dd> + <p>By default, redirecting to an HTML anchor doesn't work, + because mod_rewrite escapes the <code>#</code> character, + turning it into <code>%23</code>. This, in turn, breaks the + redirection.</p> + </dd> + + <dt>Solution:</dt> + + <dd> + <p>Use the <code>[NE]</code> flag on the + <code>RewriteRule</code>. NE stands for No Escape. + </p> + </dd> + + <dt>Discussion:</dt> + <dd>This technique will of course also work with other + special characters that mod_rewrite, by default, URL-encodes.</dd> + </dl> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="time-dependent" id="time-dependent">Time-Dependent Rewriting</a></h2> + + + + <dl> + <dt>Description:</dt> + + <dd> + <p>We wish to use mod_rewrite to serve different content based on + the time of day.</p> + </dd> + + <dt>Solution:</dt> + + <dd> + <p>There are a lot of variables named <code>TIME_xxx</code> + for rewrite conditions. In conjunction with the special + lexicographic comparison patterns <code><STRING</code>, + <code>>STRING</code> and <code>=STRING</code> we can + do time-dependent redirects:</p> + +<pre class="prettyprint lang-config">RewriteEngine on +RewriteCond "%{TIME_HOUR}%{TIME_MIN}" ">0700" +RewriteCond "%{TIME_HOUR}%{TIME_MIN}" "<1900" +RewriteRule "^foo\.html$" "foo.day.html" [L] +RewriteRule "^foo\.html$" "foo.night.html"</pre> + + + <p>This provides the content of <code>foo.day.html</code> + under the URL <code>foo.html</code> from + <code>07:01-18:59</code> and at the remaining time the + contents of <code>foo.night.html</code>.</p> + + <div class="warning"><code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code>, intermediate proxies + and browsers may each cache responses and cause the either page to be + shown outside of the time-window configured. + <code class="module"><a href="../mod/mod_expires.html">mod_expires</a></code> may be used to control this + effect. You are, of course, much better off simply serving the + content dynamically, and customizing it based on the time of day.</div> + + </dd> + </dl> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="setenvvars" id="setenvvars">Set Environment Variables Based On URL Parts</a></h2> + + + + <dl> + <dt>Description:</dt> + + <dd> + <p>At times, we want to maintain some kind of status when we + perform a rewrite. For example, you want to make a note that + you've done that rewrite, so that you can check later to see if a + request came via that rewrite. One way to do this is by setting an + environment variable.</p> + </dd> + + <dt>Solution:</dt> + + <dd> + <p>Use the [E] flag to set an environment variable.</p> + +<pre class="prettyprint lang-config">RewriteEngine on +RewriteRule "^/horse/(.*)" "/pony/$1" [E=<strong>rewritten:1</strong>]</pre> + + + <p>Later in your ruleset you might check for this environment + variable using a RewriteCond:</p> + +<pre class="prettyprint lang-config">RewriteCond "%{ENV:rewritten}" "=1"</pre> + + + <p>Note that environment variables do not survive an external + redirect. You might consider using the [CO] flag to set a + cookie. For per-directory and htaccess rewrites, where the final + substitution is processed as an internal redirect, environment + variables from the previous round of rewriting are prefixed with + "REDIRECT_". </p> + + </dd> + </dl> + +</div></div> +<div class="bottomlang"> +<p><span>Available Languages: </span><a href="../en/rewrite/advanced.html" title="English"> en </a> | +<a href="../fr/rewrite/advanced.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p> +</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed by our moderators if they are either implemented or considered invalid/off-topic. 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