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[[Category: Cookbook]]

Some sites with multiple virtual hosts may want to load balance to two separate backend clusters. For example, a www.foo.com might have 3 servers in its backend cluster and www.bar.com might only have 1 server in its backend cluster. Because Resin's <resin:LoadBalance> tag is flexible, you can use it to split the traffic as your site needs.

== resin.xml for www.foo.com and www.bar.com ==

This configuration has 5 servers in three separate clusters defined in a single resin.xml file. Although you can split the configuration into multiple files using <resin:import>, the basic single-file configuration is designed so you can review the entire system at once, instead of managing lots of configuration files.

Features:

* HTTP load balancing on port 80 of server 192.168.1.10 (the web-tier)
* www.foo.com handled by 3 servers: 192.168.2.10, 192.168.2.11, 192.168.2.12
* www.bar.com handled by 1 server: 192.168.3.10
* proxy-cache enabled on the web-tier, improving performance for all servers
* the web-tier server runs as "resin" user for security

=== resin.xml ===

 <resin xmlns="http://caucho.com/ns/resin">
        xmlns:resin="urn:java:com.caucho.resin">
  
   <cluster-default>
     <resin:import path="${__DIR__}/app-default.xml"/>
   </cluster-default>
 
   <cluster id="web-tier">
 
     <server id="http-a" address="192.168.1.10" port="6800">
       <http port="80"/>
       <user-name>resin</user-name>
       <group-name>resin</group-name>
     </server>
 
     <proxy-cache/>
 
     <host id="www.foo.com">
       <web-app id="/">
         <resin:LoadBalance regexp="^" cluster="foo-tier"/>
       </web-app>
     </host>
 
     <host id="www.bar.com">
       <web-app id="/">
         <resin:LoadBalance regexp="^" cluster="bar-tier"/>
       </web-app>
     </host>
   </cluster>
 
   <cluster id="foo-tier">
      <server id="foo-a" address="192.168.2.10" port="6800"/>
      <server id="foo-b" address="192.168.2.11" port="6800"/>
      <server id="foo-c" address="192.168.2.12" port="6800"/>
  
      <host id="/" root-directory="/var/www/www.foo.com">
        <web-app-deploy path="webapps"/>
      </host>
   </cluster>
 
 
   <cluster id="bar-tier">
      <server id="bar-a" address="192.168.3.10" port="6800"/>
  
      <host id="/" root-directory="/var/www/www.bar.com">
        <web-app-deploy path="webapps"/>
      </host>
   </cluster>
  </resin>