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diff --git a/usr.sbin/httpd/htdocs/manual/vhosts/virtual-host.html b/usr.sbin/httpd/htdocs/manual/vhosts/virtual-host.html new file mode 100644 index 00000000000..a419be1e738 --- /dev/null +++ b/usr.sbin/httpd/htdocs/manual/vhosts/virtual-host.html @@ -0,0 +1,222 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> +<HTML> +<HEAD> +<TITLE>Apache Server Virtual Host Support</TITLE> +</HEAD> + +<!-- Background white, links blue (unvisited), navy (visited), red (active) --> +<BODY + BGCOLOR="#FFFFFF" + TEXT="#000000" + LINK="#0000FF" + VLINK="#000080" + ALINK="#FF0000" +> +<DIV ALIGN="CENTER"> + <IMG SRC="../images/sub.gif" ALT="[APACHE DOCUMENTATION]"> + <H3> + Apache HTTP Server Version 1.3 + </H3> +</DIV> + +<H1 ALIGN="CENTER">Virtual Host Support</H1> + +<STRONG>See Also:</STRONG> +<A HREF="host.html">Non-IP based virtual hosts</A> + +<H2>What are virtual hosts?</H2> +This is the ability of a single machine to be a web server for multiple +domains. For example, an Internet service provider might have a machine +called <CODE>www.serve.com</CODE> which provides Web space for several +organizations including, say, <EM>smallco</EM> and <EM>baygroup</EM>. +Ordinarily, these groups would be given parts of the Web tree on www.serve.com. +So smallco's home page would have the URL +<BLOCKQUOTE> +http://www.serve.com/smallco/ +</BLOCKQUOTE> +and baygroup's home page would have the URL +<BLOCKQUOTE> +http://www.serve.com/baygroup/ +</BLOCKQUOTE> +<P> +For esthetic reasons, however, both organizations would rather their home +pages appeared under their own names rather than that of the service +provider's; but they do not want to set up their own Internet links and +servers. +<P> +Virtual hosts are the solution to this problem. smallco and baygroup would +have their own Internet name registrations, <CODE>www.smallco.com</CODE> and +<CODE>www.baygroup.org</CODE> respectively. These hostnames would both +correspond to the service provider's machine (www.serve.com). Thus +smallco's home page would now have the URL +<BLOCKQUOTE> +http://www.smallco.com/ +</BLOCKQUOTE> +and baygroup's home page would would have the URL +<BLOCKQUOTE> +http://www.baygroup.org/ +</BLOCKQUOTE> + +<H2>System requirements</H2> +Due to limitations in the HTTP/1.0 protocol, the web server <STRONG>must have a +different IP address for each virtual host</STRONG>. This can be achieved +by the machine having several physical network connections, or by use +of a <A HREF="../misc/vif-info.html">virtual interface</A> on some operating +systems. + +<H2>How to set up Apache</H2> +There are two ways of configuring apache to support multiple hosts. +Either by running a separate httpd daemon for each hostname, or by running a +single daemon which supports all the virtual hosts. +<P> +Use multiple daemons when: +<UL> +<LI>The different virtual hosts need very different httpd configurations, such + as different values for: + <A HREF="../mod/core.html#servertype">ServerType</A>, + <A HREF="../mod/core.html#user">User</A>, + <A HREF="../mod/core.html#group">Group</A>, + <A HREF="../mod/mod_mime.html#typesconfig">TypesConfig</A> or + <A HREF="../mod/core.html#serverroot">ServerRoot</A>. +<LI>The machine does not process a very high request rate. +</UL> +Use a single daemon when: +<UL> +<LI>Sharing of the httpd configuration between virtual hosts is acceptable. +<LI>The machine services a large number of requests, and so the performance + loss in running separate daemons may be significant. +</UL> + +<H2>Setting up multiple daemons</H2> +Create a separate httpd installation for each virtual host. +For each installation, use the +<A HREF="../mod/core.html#bindaddress">BindAddress</A> directive in the +configuration +file to select which IP address (or virtual host) that daemon services. +<EM>E.g.</EM>, +<BLOCKQUOTE><CODE>BindAddress www.smallco.com</CODE></BLOCKQUOTE> +This hostname can also be given as an IP address. + +<H2>Setting up a single daemon</H2> +For this case, a single httpd will service requests for all the virtual hosts. +The <A HREF="../mod/core.html#virtualhost">VirtualHost</A> directive in the + configuration file is used to set the values of +<A HREF="../mod/core.html#serveradmin">ServerAdmin</A>, +<A HREF="../mod/core.html#servername">ServerName</A>, +<A HREF="../mod/core.html#documentroot">DocumentRoot</A>, +<A HREF="../mod/core.html#errorlog">ErrorLog</A> and +<A HREF="../mod/mod_log_config.html#transferlog">TransferLog</A> configuration +directives to different values for each virtual host. +<EM>E.g.</EM>, +<BLOCKQUOTE><CODE> +<VirtualHost www.smallco.com><BR> +ServerAdmin webmaster@mail.smallco.com<BR> +DocumentRoot /groups/smallco/www<BR> +ServerName www.smallco.com<BR> +ErrorLog /groups/smallco/logs/error_log<BR> +TransferLog /groups/smallco/logs/access_log<BR> +</VirtualHost><BR> +<BR> +<VirtualHost www.baygroup.org><BR> +ServerAdmin webmaster@mail.baygroup.org<BR> +DocumentRoot /groups/baygroup/www<BR> +ServerName www.baygroup.org<BR> +ErrorLog /groups/baygroup/logs/error_log<BR> +TransferLog /groups/baygroup/logs/access_log<BR> +</VirtualHost><BR> +</CODE></BLOCKQUOTE> + +This VirtualHost hostnames can also be given as IP addresses. + +<P> + +Almost <STRONG>ANY</STRONG> configuration directive can be put +in the VirtualHost directive, with the exception of +<A HREF="../mod/core.html#servertype">ServerType</A>, +<A HREF="../mod/core.html#user">User</A>, +<A HREF="../mod/core.html#group">Group</A>, +<A HREF="../mod/core.html#startservers">StartServers</A>, +<A HREF="../mod/core.html#maxspareservers">MaxSpareServers</A>, +<A HREF="../mod/core.html#minspareservers">MinSpareServers</A>, +<A HREF="../mod/core.html#maxrequestsperchild">MaxRequestsPerChild</A>, +<A HREF="../mod/core.html#bindaddress">BindAddress</A>, +<A HREF="../mod/core.html#pidfile">PidFile</A>, +<A HREF="../mod/mod_mime.html#typesconfig">TypesConfig</A>, and +<A HREF="../mod/core.html#serverroot">ServerRoot</A>. + +<P> + +<EM>SECURITY:</EM> When specifying where to write log files, be aware +of some security risks which are present if anyone other than the +user that starts Apache has write access to the directory where they +are written. See the <A HREF="../misc/security_tips.html">security +tips</A> document for details. + +<P> + +<H2>File Handle/Resource Limits:</H2> +When using a large number of Virtual Hosts, Apache may run out of available +file descriptors if each Virtual Host specifies different log files. +The total number of file descriptors used by Apache is one for each distinct +error log file, one for every other log file directive, plus 10-20 for +internal use. Unix operating systems limit the number of file descriptors that +may be used by a process; the limit is typically 64, and may usually be +increased up to a large hard-limit. +<P> +Although Apache attempts to increase the limit as required, this +may not work if: +<OL> +<LI>Your system does not provide the setrlimit() system call. +<LI>The setrlimit(RLIMIT_NOFILE) call does not function on your system + (such as Solaris 2.3) +<LI>The number of file descriptors required exceeds the hard limit. +<LI>Your system imposes other limits on file descriptors, such as a limit +on stdio streams only using file descriptors below 256. (Solaris 2) +</OL> + +In the event of problems you can: +<UL> +<LI>Reduce the number of log files; don't specify log files in the VirtualHost +sections, but only log to the main log files. +<LI>If you system falls into 1 or 2 (above), then increase the file descriptor +limit before starting Apache, using a script like +<BLOCKQUOTE><CODE> +#!/bin/sh <BR> +ulimit -S -n 100 <BR> +exec httpd</CODE></BLOCKQUOTE> +</UL> + +The have been reports that Apache may start running out of resources allocated +for the root process. This will exhibit itself as errors in the error log like +"unable to fork". There are two ways you can bump this up: + +<OL> +<LI>Have a <CODE>csh</CODE> script wrapper around httpd which sets the +"rlimit" to some large number, like 512. +<LI>Edit http_main.c to add calls to setrlimit() from main(), along the lines +of +<PRE> + struct rlimit rlp; + + rlp.rlim_cur = rlp.rlim_max = 512; + if (setrlimit(RLIMIT_NPROC, &rlp)) { + fprintf(stderr, "setrlimit(RLIMIT_NPROC) failed.\n"); + exit(1); + } +</PRE> +(thanks to "Aaron Gifford <agifford@InfoWest.COM>" for the patch) +</OL> + +The latter will probably manifest itself in a later version of Apache. + +<HR> + +<H3 ALIGN="CENTER"> + Apache HTTP Server Version 1.3 +</H3> + +<A HREF="./"><IMG SRC="../images/index.gif" ALT="Index"></A> +<A HREF="../"><IMG SRC="../images/home.gif" ALT="Home"></A> + +</BODY> +</HTML> |