1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
|
<?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>
<meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type" />
<!--
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
This file is generated from xml source: DO NOT EDIT
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
-->
<title>Dynamically Configured Mass Virtual Hosting - Apache HTTP Server Version 2.5</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/quickreference.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 2.5</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 2.5</a> > <a href="./">Virtual Hosts</a></div><div id="page-content"><div id="preamble"><h1>Dynamically Configured Mass Virtual Hosting</h1>
<div class="toplang">
<p><span>Available Languages: </span><a href="../en/vhosts/mass.html" title="English"> en </a> |
<a href="../fr/vhosts/mass.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
<a href="../ko/vhosts/mass.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> |
<a href="../tr/vhosts/mass.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
</div>
<p>This document describes how to efficiently serve an
arbitrary number of virtual hosts with the Apache HTTP Server. A
<a href="../rewrite/vhosts.html">separate document</a> discusses using
<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> to create dynamic mass virtual hosts.
</p>
</div>
<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#motivation">Motivation</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#overview">Overview</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#simple">Dynamic Virtual Hosts with
mod_vhost_alias</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#homepages">Simplified Dynamic Virtual Hosts</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#combinations">Using Multiple Virtual
Hosting Systems on the Same Server</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#ipbased">More Efficient IP-Based Virtual Hosting</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#rewrite">Mass virtual hosts with
mod_rewrite</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#macro">Mass virtual hosts with mod_macro</a></li>
</ul><h3>See also</h3><ul class="seealso"><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="motivation" id="motivation">Motivation</a> <a title="Permanent link" href="#motivation" class="permalink">¶</a></h2>
<p>The techniques described here are of interest if your
<code>httpd.conf</code> contains many
<code><VirtualHost></code> sections that are
substantially the same, for example:</p>
<pre class="prettyprint lang-config"><VirtualHost 111.22.33.44>
ServerName customer-1.example.com
DocumentRoot "/www/hosts/customer-1.example.com/docs"
ScriptAlias "/cgi-bin/" "/www/hosts/customer-1.example.com/cgi-bin"
</VirtualHost>
<VirtualHost 111.22.33.44>
ServerName customer-2.example.com
DocumentRoot "/www/hosts/customer-2.example.com/docs"
ScriptAlias "/cgi-bin/" "/www/hosts/customer-2.example.com/cgi-bin"
</VirtualHost>
<VirtualHost 111.22.33.44>
ServerName customer-N.example.com
DocumentRoot "/www/hosts/customer-N.example.com/docs"
ScriptAlias "/cgi-bin/" "/www/hosts/customer-N.example.com/cgi-bin"
</VirtualHost></pre>
<p>We wish to replace these multiple
<code><VirtualHost></code> blocks with a mechanism
that works them out dynamically. This has a number of
advantages:</p>
<ol>
<li>Your configuration file is smaller, so Apache starts
more quickly and uses less memory. Perhaps more importantly, the
smaller configuration is easier to maintain, and leaves less room
for errors.</li>
<li>Adding virtual hosts is simply a matter of creating the
appropriate directories in the filesystem and entries in the
DNS - you don't need to reconfigure or restart Apache.</li>
</ol>
<p>The main disadvantage is that you cannot have a different log file for
each virtual host; however, if you have many virtual hosts, doing
this can be a bad idea anyway, because of the <a href="fd-limits.html">number of file descriptors needed</a>.
It is better to <a href="../logs.html#piped">log to a pipe or a fifo</a>,
and arrange for the process at the other end to split up the log
files into one per virtual host. One example of such a process can
be found in the <a href="../programs/split-logfile.html">split-logfile</a>
utility.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="overview" id="overview">Overview</a> <a title="Permanent link" href="#overview" class="permalink">¶</a></h2>
<p>A virtual host is defined by two pieces of information: its
IP address, and the contents of the <code>Host:</code> header
in the HTTP request. The dynamic mass virtual hosting technique
used here is based on automatically inserting this information into the
pathname of the file that is used to satisfy the request. This
can be most easily done by using <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code>
with Apache httpd. Alternatively,
<a href="../rewrite/vhosts.html">mod_rewrite can
be used</a>.</p>
<p>Both of these modules are disabled by default; you must enable
one of them when configuring and building Apache httpd if you want to
use this technique.</p>
<p>A couple of things need to be determined from the request in
order to make the dynamic
virtual host look like a normal one. The most important is the
server name, which is used by the server to generate
self-referential URLs etc. It is configured with the
<code>ServerName</code> directive, and it is available to CGIs
via the <code>SERVER_NAME</code> environment variable. The
actual value used at run time is controlled by the <code class="directive"><a href="../mod/core.html#usecanonicalname">UseCanonicalName</a></code>
setting. With <code>UseCanonicalName Off</code>, the server name
is taken from the contents of the <code>Host:</code> header in the
request. With <code>UseCanonicalName DNS</code>, it is taken from a
reverse DNS lookup of the virtual host's IP address. The former
setting is used for name-based dynamic virtual hosting, and the
latter is used for IP-based hosting. If httpd cannot work out
the server name because there is no <code>Host:</code> header,
or the DNS lookup fails, then the value configured with
<code>ServerName</code> is used instead.</p>
<p>The other thing to determine is the document root (configured
with <code>DocumentRoot</code> and available to CGI scripts via the
<code>DOCUMENT_ROOT</code> environment variable). In a normal
configuration, this is used by the core module when
mapping URIs to filenames, but when the server is configured to
do dynamic virtual hosting, that job must be taken over by another
module (either <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> or
<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>), which has a different way of doing
the mapping. Neither of these modules is responsible for
setting the <code>DOCUMENT_ROOT</code> environment variable so
if any CGIs or SSI documents make use of it, they will get a
misleading value.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="simple" id="simple">Dynamic Virtual Hosts with
mod_vhost_alias</a> <a title="Permanent link" href="#simple" class="permalink">¶</a></h2>
<p>This extract from <code>httpd.conf</code> implements the
virtual host arrangement outlined in the <a href="#motivation">Motivation</a> section above
using <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code>.</p>
<pre class="prettyprint lang-config"># get the server name from the Host: header
UseCanonicalName Off
# this log format can be split per-virtual-host based on the first field
# using the split-logfile utility.
LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon
CustomLog "logs/access_log" vcommon
# include the server name in the filenames used to satisfy requests
VirtualDocumentRoot "/www/hosts/%0/docs"
VirtualScriptAlias "/www/hosts/%0/cgi-bin"</pre>
<p>This configuration can be changed into an IP-based virtual
hosting solution by just turning <code>UseCanonicalName
Off</code> into <code>UseCanonicalName DNS</code>. The server
name that is inserted into the filename is then derived from
the IP address of the virtual host. The variable <code>%0</code>
references the requested servername, as indicated in the
<code>Host:</code> header.</p>
<p>See the <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> documentation for more usage
examples.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="homepages" id="homepages">Simplified Dynamic Virtual Hosts</a> <a title="Permanent link" href="#homepages" class="permalink">¶</a></h2>
<p>This is an adjustment of the above system, tailored for an
ISP's web hosting server. Using <code>%2</code>,
we can select substrings of the server name to
use in the filename so that, for example, the documents for
<code>www.user.example.com</code> are found in
<code>/home/user/www</code>. It uses a single <code>cgi-bin</code>
directory instead of one per virtual host.</p>
<pre class="prettyprint lang-config">UseCanonicalName Off
LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon
CustomLog "logs/access_log" vcommon
# include part of the server name in the filenames
VirtualDocumentRoot "/home/%2/www"
# single cgi-bin directory
ScriptAlias "/cgi-bin/" "/www/std-cgi/"</pre>
<p>There are examples of more complicated
<code>VirtualDocumentRoot</code> settings in the
<code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> documentation.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="combinations" id="combinations">Using Multiple Virtual
Hosting Systems on the Same Server</a> <a title="Permanent link" href="#combinations" class="permalink">¶</a></h2>
<p>With more complicated setups, you can use httpd's normal
<code><VirtualHost></code> directives to control the
scope of the various virtual hosting configurations. For
example, you could have one IP address for general customers' homepages,
and another for commercial customers, with the following setup.
This can be combined with conventional
<code><VirtualHost></code> configuration sections, as shown
below.</p>
<pre class="prettyprint lang-config">UseCanonicalName Off
LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon
<Directory "/www/commercial">
Options FollowSymLinks
AllowOverride All
</Directory>
<Directory "/www/homepages">
Options FollowSymLinks
AllowOverride None
</Directory>
<VirtualHost 111.22.33.44>
ServerName www.commercial.example.com
CustomLog "logs/access_log.commercial" vcommon
VirtualDocumentRoot "/www/commercial/%0/docs"
VirtualScriptAlias "/www/commercial/%0/cgi-bin"
</VirtualHost>
<VirtualHost 111.22.33.45>
ServerName www.homepages.example.com
CustomLog "logs/access_log.homepages" vcommon
VirtualDocumentRoot "/www/homepages/%0/docs"
ScriptAlias "/cgi-bin/" "/www/std-cgi/"
</VirtualHost></pre>
<div class="note">
<h3>Note</h3>
<p>If the first VirtualHost block does <em>not</em> include a
<code class="directive"><a href="../mod/core.html#servername">ServerName</a></code> directive, the reverse
DNS of the relevant IP will be used instead.
If this is not the server name you
wish to use, a bogus entry (eg. <code>ServerName
none.example.com</code>) can be added to get around this
behaviour.</p>
</div>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="ipbased" id="ipbased">More Efficient IP-Based Virtual Hosting</a> <a title="Permanent link" href="#ipbased" class="permalink">¶</a></h2>
<p>The configuration changes suggested to turn <a href="#simple">the first
example</a> into an IP-based virtual hosting setup result in
a rather inefficient setup. A new DNS lookup is required for every
request. To avoid this overhead, the filesystem can be arranged to
correspond to the IP addresses, instead of to the host names, thereby
negating the need for a DNS lookup. Logging will also have to be adjusted
to fit this system.</p>
<pre class="prettyprint lang-config"># get the server name from the reverse DNS of the IP address
UseCanonicalName DNS
# include the IP address in the logs so they may be split
LogFormat "%A %h %l %u %t \"%r\" %s %b" vcommon
CustomLog "logs/access_log" vcommon
# include the IP address in the filenames
VirtualDocumentRootIP "/www/hosts/%0/docs"
VirtualScriptAliasIP "/www/hosts/%0/cgi-bin"</pre>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="rewrite" id="rewrite">Mass virtual hosts with
mod_rewrite</a> <a title="Permanent link" href="#rewrite" class="permalink">¶</a></h2>
<p>
Mass virtual hosting may also be accomplished using
<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>, either using simple <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directives, or using more
complicated techniques such as storing the vhost definitions externally
and accessing them via <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>. These techniques are
discussed in the <a href="../rewrite/vhosts.html">rewrite
documentation</a>.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="macro" id="macro">Mass virtual hosts with mod_macro</a> <a title="Permanent link" href="#macro" class="permalink">¶</a></h2>
<p>Another option for dynamically generated virtual hosts is
<code class="module"><a href="../mod/mod_macro.html">mod_macro</a></code>, with which you can create a virtualhost
template, and invoke it for multiple hostnames. An example of this is
provided in the <strong>Usage</strong> section of the module
documentation.
</p>
</div></div>
<div class="bottomlang">
<p><span>Available Languages: </span><a href="../en/vhosts/mass.html" title="English"> en </a> |
<a href="../fr/vhosts/mass.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
<a href="../ko/vhosts/mass.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> |
<a href="../tr/vhosts/mass.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </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 again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
<script type="text/javascript"><!--//--><![CDATA[//><!--
var comments_shortname = 'httpd';
var comments_identifier = 'http://httpd.apache.org/docs/trunk/vhosts/mass.html';
(function(w, d) {
if (w.location.hostname.toLowerCase() == "httpd.apache.org") {
d.write('<div id="comments_thread"><\/div>');
var s = d.createElement('script');
s.type = 'text/javascript';
s.async = true;
s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier;
(d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s);
}
else {
d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>');
}
})(window, document);
//--><!]]></script></div><div id="footer">
<p class="apache">Copyright 2019 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/quickreference.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></div><script type="text/javascript"><!--//--><![CDATA[//><!--
if (typeof(prettyPrint) !== 'undefined') {
prettyPrint();
}
//--><!]]></script>
</body></html>
|
