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diff --git a/docs/manual/rewrite/avoid.html.en b/docs/manual/rewrite/avoid.html.en new file mode 100644 index 00000000..b5e6ae51 --- /dev/null +++ b/docs/manual/rewrite/avoid.html.en @@ -0,0 +1,227 @@ +<?xml version="1.0" encoding="ISO-8859-1"?> +<!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><!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>When not to use mod_rewrite - Apache HTTP Server</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 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="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p> +<p class="apache">Apache HTTP Server Version 2.2</p> +<img alt="" src="../images/feather.gif" /></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 2.2</a> > <a href="./">Rewrite</a></div><div id="page-content"><div id="preamble"><h1>When not to use mod_rewrite</h1> +<div class="toplang"> +<p><span>Available Languages: </span><a href="../en/rewrite/avoid.html" title="English"> en </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 describes +perhaps one of the most important concepts about mod_rewrite - namely, +when to avoid using it.</p> + +<p>mod_rewrite should be considered a last resort, when other +alternatives are found wanting. Using it when there are simpler +alternatives leads to configurations which are confusing, fragile, and +hard to maintain. Understanding what other alternatives are available is +a very important step towards mod_rewrite mastery.</p> + +<p>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.</p> + +<p>The most common situation in which <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> is +the right tool is when the very best solution requires access to the +server configuration files, and you don't have that access. Some +configuration directives are only available in the server configuration +file. So if you are in a hosting situation where you only have .htaccess +files to work with, you may need to resort to +<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>.</p> + +</div> +<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#redirect">Simple Redirection</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#alias">URL Aliasing</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#vhosts">Virtual Hosting</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#proxy">Simple Proxying</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#setenv">Environment Variable Testing</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="advanced.html">Advanced techniques and tricks</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="redirect" id="redirect">Simple Redirection</a></h2> + + +<p><code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code> provides the <code class="directive"><a href="../mod/mod_alias.html#redirect">Redirect</a></code> and <code class="directive"><a href="../mod/mod_alias.html#redirectmatch">RedirectMatch</a></code> directives, which provide a +means to redirect one URL to another. This kind of simple redirection of +one URL, or a class of URLs, to somewhere else, should be accomplished +using these directives rather than <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code>. <code>RedirectMatch</code> +allows you to include a regular expression in your redirection criteria, +providing many of the benefits of using <code>RewriteRule</code>.</p> + +<p>A common use for <code>RewriteRule</code> is to redirect an entire +class of URLs. For example, all URLs in the <code>/one</code> directory +must be redirected to <code>http://one.example.com/</code>, or perhaps +all <code>http</code> requests must be redirected to +<code>https</code>.</p> + +<p>These situations are better handled by the <code>Redirect</code> +directive. Remember that <code>Redirect</code> preserves path +information. That is to say, a redirect for a URL <code>/one</code> will +also redirect all URLs under that, such as <code>/one/two.html</code> +and <code>/one/three/four.html</code>.</p> + +<p>To redirect URLs under <code>/one</code> to +<code>http://one.example.com</code>, do the following:</p> + +<div class="example"><p><code> +Redirect /one/ http://one.example.com/ +</code></p></div> + +<p>To redirect <code>http</code> URLs to <code>https</code>, do the +following:</p> + +<div class="example"><p><code> +<VirtualHost *:80> +ServerName www.example.com<br /> +Redirect / https://www.example.com/<br /> +</VirtualHost > +<br /> +<VirtualHost *:443> +ServerName www.example.com<br /> +<br /> +# ... SSL configuration goes here<br /> +</VirtualHost > +</code></p></div> + +<p>The use of <code>RewriteRule</code> to perform this task may be +appropriate if there are other <code>RewriteRule</code> directives in +the same scope. This is because, when there are <code>Redirect</code> +and <code>RewriteRule</code> directives in the same scope, the +<code>RewriteRule</code> directives will run first, regardless of the +order of appearance in the configuration file.</p> + +<p>In the case of the <em>http-to-https</em> redirection, the use of +<code>RewriteRule</code> would be appropriate if you don't have access +to the main server configuration file, and are obliged to perform this +task in a <code>.htaccess</code> file instead.</p> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="alias" id="alias">URL Aliasing</a></h2> +<p>The <code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code> directive +provides mapping from a URI to a directory - usually a directory outside +of your <code class="directive"><a href="../mod/core.html#documentroot">DocumentRoot</a></code>. Although it +is possible to perform this mapping with <code>mod_rewrite</code>, +<code>Alias</code> is the preferred method, for reasons of simplicity +and performance.</p> + +<div class="example"><h3>Using Alias</h3><p><code> +Alias /cats /var/www/virtualhosts/felines/htdocs +</code></p></div> + +<p> +The use of <code>mod_rewrite</code> to perform this mapping may be +appropriate when you do not have access to the server configuration +files. Alias may only be used in server or virtualhost context, and not +in a <code>.htaccess</code> file. +</p> + +<p>Symbolic links would be another way to accomplish the same thing, if +you have <code>Options FollowSymLinks</code> enabled on your +server.</p> +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="vhosts" id="vhosts">Virtual Hosting</a></h2> +<p>Although it is possible to handle <a href="vhosts.html">virtual hosts +with mod_rewrite</a>, it is seldom the right way. Creating individual +<VirtualHost> blocks is almost always the right way to go. In the +event that you have an enormous number of virtual hosts, consider using +<code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> to create these hosts automatically.</p> + +<p>Third-party modules such as <a href="link_needed">mod_macro</a> are +also useful for creating a large number of virtual hosts dynamically.</p> + +<p>Using <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> for vitualhost creation may be +appropriate if you are using a hosting service that does not provide +you access to the server configuration files, and you are therefore +restricted to configuration using <code>.htaccess</code> files.</p> + +<p>See the <a href="vhosts.html">virtual hosts with mod_rewrite</a> +document for more details on how you might accomplish this if it still +seems like the right approach.</p> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="proxy" id="proxy">Simple Proxying</a></h2> + +<p><code>RewriteRule</code> provides the <a href="flags.html#flag_p">[P]</a> flag to pass rewritten URIs through +<code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>.</p> + +<div class="example"><p><code> +RewriteRule ^/?images(.*) http://imageserver.local/images$1 [P] +</code></p></div> + +<p>However, in many cases, when there is no actual pattern matching +meeded, as in the example shown above, the <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code> directive is a better choice. +The example here could be rendered as:</p> + +<div class="example"><p><code> +ProxyPass /images/ http://imageserver.local/images/ +</code></p></div> + +<p>Note that whether you use <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> or <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code>, you'll still need to use the +<code class="directive"><a href="../mod/mod_proxy.html#proxypassreverse">ProxyPassReverse</a></code> directive to +catch redirects issued from the back-end server:</p> + +<div class="example"><p><code> +ProxyPassReverse /images/ http://imageserver.local/images/ +</code></p></div> + +<p>You may need to use <code>RewriteRule</code> instead when there are +other <code>RewriteRule</code>s in effect in the same scope, as a +<code>RewriteRule</code> will usually take effect before a +<code>ProxyPass</code>, and so may preempt what you're trying to +accomplish.</p> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="setenv" id="setenv">Environment Variable Testing</a></h2> + +<p><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> is frequently used to take a particular +action based on the presence or absense of a particular environment +variable or request header. This can be done more efficiently using the +<code class="directive"><a href="../mod/core.html#if"><If></a></code>.</p> + +<p>Consider, for example, the common scenario where +<code class="directive">RewriteRule</code> is used to enforce a canonical +hostname, such as <code>www.example.com</code> instead of +<code>example.com</code>. This can be done using the <code class="directive"><a href="../mod/core.html#if"><If></a></code> direct, as shown here:</p> + +<div class="example"><p><code> +<If "$req{Host} = 'example.com'"><br /> +RedirectMatch (.*) http://www.example.com$1 +</If> +</code></p></div> + +<p>This technique can be used to take actions based on any request +header, response header, or environment variable, replacing +<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> in many common scenarios.</p> + +<p>See especially the <a href="../expr.html">expression evaluation +documentation</a> for a overview of what types of expressions you can +use in <If> sections, and in certain other directives.</p> + +</div></div> +<div class="bottomlang"> +<p><span>Available Languages: </span><a href="../en/rewrite/avoid.html" title="English"> en </a></p> +</div><div id="footer"> +<p class="apache">Copyright 2011 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div> +</body></html>
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