From: Noirin Plunkett Date: Wed, 19 Apr 2006 22:17:36 +0000 (+0000) Subject: Removing 1.3 refs from 2.x docs X-Git-Tag: 2.3.0~2434 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=7912f3af3c910d2cada45e9ea837230190a3ebd1;p=apache Removing 1.3 refs from 2.x docs git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@395411 13f79535-47bb-0310-9956-ffa450edef68 --- diff --git a/docs/manual/vhosts/mass.xml b/docs/manual/vhosts/mass.xml index 3e709c0794..9e0ef4f8f2 100644 --- a/docs/manual/vhosts/mass.xml +++ b/docs/manual/vhosts/mass.xml @@ -22,21 +22,12 @@ Virtual Hosts - Dynamically configured mass virtual hosting + Dynamically Configured Mass Virtual Hosting

This document describes how to efficiently serve an - arbitrary number of virtual hosts with Apache. + arbitrary number of virtual hosts with the Apache httpd webserver.

@@ -75,25 +66,25 @@ NameVirtualHost 111.22.33.44

The basic idea is to replace all of the static - <VirtualHost> configuration with a mechanism - that works it out dynamically. This has a number of + <VirtualHost> configurations with a mechanism + that works them out dynamically. This has a number of advantages:

    -
  1. Your configuration file is smaller so Apache starts - faster and uses less memory.
    2. +
  2. Your configuration file is smaller, so Apache starts + more quickly and uses less memory.
  3. 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.
-

The main disadvantage is that you cannot have a different - log file for each virtual host; however if you have very many - virtual hosts then doing this is dubious anyway because it eats - file descriptors. It is better to log to a pipe or a fifo and - arrange for the process at the other end to distribute the logs - to the customers (it can also accumulate statistics, etc.).

+

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 number of file + descriptors needed. It is better to log to a pipe or a fifo, and arrange for + the process at the other end to distribute the logs to the customers. + (This can also be used to accumulate statistics, etc.).

@@ -102,49 +93,48 @@ NameVirtualHost 111.22.33.44

A virtual host is defined by two pieces of information: its IP address, and the contents of the Host: header in the HTTP request. The dynamic mass virtual hosting technique - is based on automatically inserting this information into the + used here is based on automatically inserting this information into the pathname of the file that is used to satisfy the request. This - is done most easily using mod_vhost_alias, - but if you are using a version of Apache up to 1.3.6 then you - must use mod_rewrite. + can be most easily done by using mod_vhost_alias + with Apache 2.0. Alternatively, mod_rewrite can be used. Both of these modules are disabled by default; you must enable one of them when configuring and building Apache if you want to use this technique.

A couple of things need to be `faked' to make the dynamic virtual host look like a normal one. The most important is the - server name which is used by Apache to generate - self-referential URLs, etc. It is configured with the + server name, which is used by Apache to generate + self-referential URLs etc. It is configured with the ServerName directive, and it is available to CGIs via the SERVER_NAME environment variable. The actual value used at run time is controlled by the UseCanonicalName - setting. With UseCanonicalName Off the server name - comes from the contents of the Host: header in the - request. With UseCanonicalName DNS it comes from a + setting. With UseCanonicalName Off, the server name + is taken from the contents of the Host: header in the + request. With UseCanonicalName DNS, 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 Apache cannot work out - the server name because there is no Host: header - or the DNS lookup fails then the value configured with + the server name because there is no Host: header, + or the DNS lookup fails, then the value configured with ServerName is used instead.

The other thing to `fake' is the document root (configured with DocumentRoot and available to CGIs via the DOCUMENT_ROOT environment variable). In a normal - configuration this setting is used by the core module when + 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 is taken over by another + do dynamic virtual hosting, that job must be taken over by another module (either mod_vhost_alias or - mod_rewrite) which has a different way of doing + mod_rewrite), which has a different way of doing the mapping. Neither of these modules is responsible for setting the DOCUMENT_ROOT environment variable so - if any CGIs or SSI documents make use of it they will get a + if any CGIs or SSI documents make use of it, they will get a misleading value.

-
Simple dynamic virtual hosts +
Simple Dynamic Virtual Hosts

This extract from httpd.conf implements the virtual host arrangement outlined in the -

A virtually hosted homepages system +
A Virtually Hosted Homepages System -

This is an adjustment of the above system tailored for an +

This is an adjustment of the above system, tailored for an ISP's homepages server. Using a slightly more complicated - configuration we can select substrings of the server name to - use in the filename so that e.g. the documents for + configuration, we can select substrings of the server name to + use in the filename so that, for example, the documents for www.user.isp.com are found in /home/user/. It uses a single cgi-bin directory instead of one per virtual host.

@@ -198,15 +188,15 @@ ScriptAlias /cgi-bin/ /www/std-cgi/
-
Using more than - one virtual hosting system on the same server +
Using Multiple Virtual + Hosting Systems on the Same Server -

With more complicated setups you can use Apache's normal +

With more complicated setups, you can use Apache's normal <VirtualHost> directives to control the scope of the various virtual hosting configurations. For - example, you could have one IP address for homepages customers - and another for commercial customers with the following setup. - This can of course be combined with conventional + example, you could have one IP address for general customers' homepages, + and another for commercial customers, with the following setup. + This can, of course, be combined with conventional <VirtualHost> configuration sections.

@@ -253,16 +243,15 @@ LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon
-
More efficient IP-based virtual hosting +
More Efficient IP-Based Virtual Hosting -

After the first example I noted that - it is easy to turn it into an IP-based virtual hosting setup. - Unfortunately that configuration is not very efficient because - it requires a DNS lookup for every request. This can be avoided - by laying out the filesystem according to the IP addresses - themselves rather than the corresponding names and changing the - logging similarly. Apache will then usually not need to work - out the server name and so incur a DNS lookup.

+

The configuration changes suggested to turn the first + example 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.

# get the server name from the reverse DNS of the IP address
@@ -279,45 +268,20 @@ VirtualScriptAliasIP /www/hosts/%0/cgi-bin
-
Using older versions of Apache - -

The examples above rely on mod_vhost_alias - which appeared after version 1.3.6. If you are using a version - of Apache without mod_vhost_alias then you can - implement this technique with mod_rewrite as - illustrated below, but only for Host:-header-based virtual - hosts.

- -

In addition there are some things to beware of with logging. - Apache 1.3.6 is the first version to include the - %V log format directive; in versions 1.3.0 - 1.3.3 - the %v option did what %V does; - version 1.3.4 has no equivalent. In all these versions of - Apache the UseCanonicalName directive can appear - in .htaccess files which means that customers can - cause the wrong thing to be logged. Therefore the best thing to - do is use the %{Host}i directive which logs the - Host: header directly; note that this may include - :port on the end which is not the case for - %V.

- -
- -
Simple dynamic - virtual hosts using <code>mod_rewrite</code> +
Simple Dynamic + Virtual Hosts Using <module>mod_rewrite</module>

This extract from httpd.conf does the same thing as the first example. The first - half is very similar to the corresponding part above but with - some changes for backward compatibility and to make the + half is very similar to the corresponding part above, except for + some changes, required for backward compatibility and to make the mod_rewrite part work properly; the second half configures mod_rewrite to do the actual work.

-

There are a couple of especially tricky bits: By default, - mod_rewrite runs before the other URI translation - modules (mod_alias etc.) so if they are used then - mod_rewrite must be configured to accommodate - them. Also, some magic must be performed to do a +

There are a couple of especially tricky bits: by default, + mod_rewrite runs before other URI translation + modules (mod_alias etc.) - so if you wish to use these modules, mod_rewrite must be configured to accommodate + them. Also, some magic is required to do a per-dynamic-virtual-host equivalent of ScriptAlias.

@@ -362,7 +326,7 @@ RewriteRule ^/(.*)$ /www/hosts/${lowercase:%{SERVER_NAME}}/cgi-bin/$1 [H=cgi-
A - homepages system using <code>mod_rewrite</code> + Homepages System Using mod_rewrite

This does the same thing as the second example.

@@ -391,15 +355,15 @@ ScriptAlias /cgi-bin/ /www/std-cgi/
-
Using a separate virtual - host configuration file +
Using a Separate Virtual + Host Configuration File -

This arrangement uses more advanced mod_rewrite - features to get the translation from virtual host to document - root from a separate configuration file. This provides more - flexibility but requires more complicated configuration.

+

This arrangement uses more advanced mod_rewrite + features to work out the translation from virtual host to document + root, from a separate configuration file. This provides more + flexibility, but requires more complicated configuration.

-

The vhost.map file contains something like +

The vhost.map file should look something like this:

@@ -409,7 +373,7 @@ www.customer-2.com /www/customers/2
www.customer-N.com /www/customers/N
 -

The http.conf contains this:

+

The httpd.conf should contain the following:

RewriteEngine on