Multiple Domains and Web Sites in a single Joomla! installation

Although it's a best-practice to give every Website its own domain, Joomla! installation and database there can be special conditions in which a multi-site solution under a single Joomla! install is warranted.

An Example Application

A small business, 'Johnson Candies', has two separate but related brands: Red Candy and Yellow Candy. They require a single Joomla!-based Website where both candy types are visible, each with its own home page on the Joomla! site which corresponds to the domains www.redjohnsoncandy.com and www.yellowjohnsoncandy.com.

Additionally, each brand and site requires its own design: a yellow template for one; a red template, for the other.

Benefits

By including both brands in a single Joomla! web installation, Johnson Candies is able to save editing time (only one login), share articles and data across both brands (or sites) and use a single feature, such as a Contact Us form, for both brands.

Implementation Procedure

Prepare Your Domains

Use a single domain for your hosting account, as normal. Create the required add-on domains in the control panel of your hosting account. For the purpose of this tutorial, we will use www.redjohnsoncandy.com in addition to the base www.yellowjohnsoncandy.com domain name.

Install and Setup Joomla!

Install and setup Joomla! normally. Then develop articles, menus and modules for each site.

Create Templates

Next develop and install the necessary templates - one for each site that you wish to have. In the above example, you would create a template for red candy named Red Template and a template for yellow candy named Yellow Template. Once the templates are installed, assign them to the relevant menu items, using the Joomla! template manager in the Joomla! Administrator area.

Add a Redirect

Option #1: Create an .htaccess (Apache) redirect

Note Enable SEF URLs in Joomla! First

One option is to use .htaccess (Apache) to redirect inquiries to a given domain to a specific Joomla! page.

Our goal is to redirect any inquries to the Red Candy domain name to a given page on the Joomla! site. In this example, we redirect any inquiries to www.redjohnsoncandy.com to a category-blog page. You would have previously assigned the 'red candy' template to this menu item, to create the illusion of a separate site.

#The following rule works, but it changes which domain name displays.
RewriteCond %{HTTP_HOST} ^(www\.)?redjohnsoncandy\.com$
RewriteRule (.*) http://www.yellowjohnsoncandy.com/index.php?option=com_content&view=category&layout=blog&id=3&Itemid=12 [R=301,L]

Well, that works - but you can see the drawback immediately. Although the user is successfully viewing the Red Candy site, they will still see the Yellow Candy domain name. Unfortunately, if you are using both .htaccess and domain-parking (technically a redirect) - this is necessary in order to avoid creating a LOOP.

Option #2: Create a PHP Header Redirect

This solution has the benefit of keeping the illusion of separate domains/web sites apparent to the visitor. Instead of using .htaccess (Apache) for our redirect, we use one of the templates on the site.

In this example, the base domain is www.redjohnsoncandy.com. You have created a template for that area named Red Template. The trick is to open 'Red Template's' index.php file and add the following AS THE VERY FIRST LINES of the install's primary index.php.

<?php
$domain = $_SERVER["HTTP_HOST"];
$uri = $_SERVER["REQUEST_URI"];
$url = $domain . $uri;

if (($url == "redjohnsoncandy.com/") ||
   ($url == "www.redjohnsoncandy.com/")) { 
   header("Status: 301 Moved Permanently");
   header("Location: http://www.redjohnsoncandy.com/index.php?option=com_content&view=category&layout=blog&id=3&Itemid=12"); 
}
?>

Here's the benefit: The visitor will now be redirected to the appropriate Red Site page, that has the Red Template assigned to it only in the case where they have arrived at the 'red site' domain name. Otherwise, the conditional PHP rule is ignored, and the Yellow Site loads.

It is important to remember to request also de URI (url that follows the pure domain) so that you can make redirections to the same domain. When the URI is invisible in the url the variable becomes a "/" sign. That is why you have to compare your pure url with a "/" sign at the end. This way you´ll be able to make 301 redirects in the same domain. Otherwise you´ll create an infinite loop in the redirection process.

Option #3: Create a PHP Header Redirect, for multiple domains with specific domain redirects for custom templates

Solution for single webspace, with different domains, one Joomla install and depending on the user landing domain, redirects to a different default page. Paste following PHP code AS THE VERY FIRST THING in the install's primary index.php file. To assign another domain, just copy/past the "if" function and edit it with the values of the other domain in the same fashion. Further to setup the template views, you will have to assign different module item/link alias and setup template views within the Joomla! template manager. The alias setting is needed when you use SEF settings.

<?php
$domain = $_SERVER["SERVER_NAME"];
$requri = $_SERVER['REQUEST_URI'];
if (($domain == "www.example.de" && $requri == "/" || 
   $domain == "example.de"))  { 
   header("Status: 301 Moved Permanently");
   header("Location: http://www.example.de/index.php?option=com_content&view=article&id=6"); 
}
?>