OXLoadBalancingClustering SessionLoadbalancing

Session load balancing

Since configuration of system services for the corresponding operating system is already described in the general installation guides, this guide will focus on the specialties when creating a distributed setup. Please refer to the installation guides for configuration that is not mentioned in this guide.

The web server on this setup is a pure frontend server. This means it takes and responds to requests sent by a client but it does not contain any groupware logic. All requests are forwarded to the Open-Xchange Servers through the AJP13 protocol. The configuration will allow round-robin session load balancing, basically both Open-Xchange servers are configured as backends for answering requests with an 50:50 probability of being chosen. Once a new session is created, that session is bound to the groupware server it has been created.

For the web server we only need a very small set of packages, basically only packages that starts with open-xchange-gui where most of additional packages are languagepacks or plugins. Add the Open-Xchange software repository to the package manager configuration first. Then install the open-xchange-gui package to the web server.

$ apt-get install open-xchange-configjump-generic-gui \
open-xchange-gui open-xchange-gui-wizard-plugin-gui \
open-xchange-online-help-de \
open-xchange-online-help-en open-xchange-online-help-fr

This will install the Open-Xchange user interface, Apache 2 and several services as dependency. The Apache module proxy_ajp will handle all the communication with the Open-Xchange Servers. Its configuration also contains the setup of the session balancing. What it basically does is defining two backend nodes and forwarding servlet paths to them based on the loadfactor. This setting can be customized in case the backend servers are not equal in terms of performance. The route property is important, it specifies a unique ID of a backend server and will be used when setting up Open-Xchange Servers later. Please see the Apache mod_proxy_ajp documentation for more details.

$ vim /etc/apache2/conf.d/proxy_ajp.conf

<Location /servlet/axis2/services>
   # restrict access to the soap provisioning API
   Order Deny,Allow
   Deny from all
   Allow from 127.0.0.1
   # you might add more ip addresses / networks here
   # Allow from 192.168 10 172.16
</Location>



<IfModule mod_proxy_ajp.c>
  ProxyRequests Off
  <Proxy balancer://oxcluster>
      Order deny,allow
      Allow from all
      # multiple server setups need to have the hostname inserted instead localhost
      BalancerMember ajp://10.20.30.213:8009 timeout=100 smax=0 ttl=60 retry=60 loadfactor=50 route=OX1
      BalancerMember ajp://10.20.30.215:8009 timeout=100 smax=0 ttl=60 retry=60 loadfactor=50 route=OX2
      ProxySet stickysession=JSESSIONID
  </Proxy>
  <Proxy /ajax>
      ProxyPass balancer://oxcluster/ajax
  </Proxy>
  <Proxy /servlet>
      ProxyPass balancer://oxcluster/servlet
  </Proxy>
  <Proxy /infostore>
      ProxyPass balancer://oxcluster/infostore
  </Proxy>
  <Proxy /publications>
      ProxyPass balancer://oxcluster/publications
  </Proxy>
  <Proxy /Microsoft-Server-ActiveSync>
      ProxyPass balancer://oxcluster/Microsoft-Server-ActiveSync
  </Proxy>
  <Proxy /usm-json>
      ProxyPass balancer://oxcluster/usm-json
  </Proxy>
</IfModule>

Restart the Apache 2 web server and check if it is possible to connect with a browser. By default, this configuration allows plain HTTP access. In order to offer privacy to the customer the connection must be secured by a HTTPS connection based on a valid certificate. It is also recommended to set a redirect for all plain HTTP connections to use HTTPS.

Add some required apache modules to the web server. See the general installation guides for more information about configuration of expires and deflate.

$ a2enmod proxy && a2enmod proxy_ajp && a2enmod proxy_balancer && a2enmod expires && a2enmod deflate && a2enmod headers

Restart the Apache web server after applying all configuration changes.

$ /etc/init.d/apache2 restart