Configure Apache HTTPd as a reverse proxy (mod_proxy)

The communication between the HTTP server and Geronimo can be also done via AJP connectors. By default, both Apache Geronimo distributions (Jetty and Tomcat) have already predefined one AJP v13 listener, the ports where these listeners are defined varies from one distribution to the other.

For Jetty the default AJP13 listener port is 8019
For Tomcat the default AJP13 listener port is 8009

This section will cover the configuration for both Geronimo distributions as the steps are very similar (if not equal).

The Jakarta Tomcat Connector mod_jk module is provided as a connector from Apache Tomcat source, Jetty (and obviously Tomcat) is fully compatible with this connector. This module is avaiable when you download the Tomcat source, but also is available for download separately, refer to the following URL for the proper version for your system.

http://tomcat.apache.org/download-connectors.cgi

In addition to the mod_jk you will require the workers.properties file, also available with the Apache Tomcat source distribution. This properties file tells the mod_jk plugin how to connect to the Geronimo server. For a detailed explanation on all the available options for configuring the Jakarta Tomcat Connector visit the following URL:

http://tomcat.apache.org/connectors-doc/config/workers.html

For practical purposes, the module mod_jk_1.2.6_2.0.50.dll for Windows and the workers.properties are included in the Attachments section in this article.

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Configure Apache HTTPd

Download the appropriate mod_jk for your platform from the Tomcat web site, rename it to mod_jk.dll (or .so depending on your platform) and copy it into the <httpd_home>\modules directory. Download and extract the workers.properties from the Apache Tomcat source (alternatively, download it from the Attachments section) to the <httpd_home>\conf directory.

Edit the httpd.conf file located in the <httpd_home>\conf directory to load the Jakarta Tomcat Connector mod_jk module. Add the following lines at the end of the httpd.conf file.

LoadModule jk_module modules/mod_jk.dll				
# Loads the Jakarta Tomcat Connector module

JkWorkersFile <httpd_home>\conf\workers.properties
# Tells the module the location of the workers.properties file

JkLogFile     <httpd_home>\logs\mod_jk.log
# Specifies the location for this module's specific log file

JkLogLevel    info
# Sets the module's log level to info

JkLogStampFormat "[%a %b %d %H:%M:%S %Y] "
# Sets the module's log time stamp format

JkAutoAlias <httpd_home>\config-store
# Automatically Alias webapp context directories into the Apache document space.

JkMount /console/* ajp13
# Sets a mount point from a context to a Tomcat worker. In this case will allow access (forward the request) to the console.

JkMount will map anything behind /console/ to the worker ajp13. The name ajp13 is defined in the workers.properties file which is described next. You will need to add more JkMount directives depending on the applications you want to be accessed via the remote HTTPd.

In this example the console has been enabled just for demonstation purposes. In a production environment you will not want to have the console accessible from the other network (normally the Internet). Having the console accessible represents a big security exposure.

The rule is that everything should have restricted access, normally a firewall would be placed in between the HTTP and the application server (depending on the topology) and you should map just the minumum resources necessary to have your application working from the other side.

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Configure workers.properties

The workers.properties, among other things, tells the HTTPd where the Geronimo server is, what version of AJP should use and the port where Geronimo is listening.

Edit the workers.properties file located in the <httpd_home>\conf directory to match your environment. The following example is an excerpt from the workers.properties file with just the variables you should focus on.

workers.java_home=<java_home>
# Sets the JAVA_HOME

ps=\
# For Windows systems use back slash "\" , for Unix systems use forward slash "/"

worker.ajp13.port=8009
# Use default 8009 for Apache Tomcat
# Change this value to 8019 for Jetty

worker.ajp13.host=localhost
# Specifies the location of the Geronimo server. Use default localhost for single-tier scenarios. Specify the hostname of the Geronimo server for multi-tier environments.

worker.ajp13.type=ajp13
# Sets the version of AJP used. The AJP listeners defined in Geronimo are AJP v13.

From this example note how the name of the worker is defined, look at the variables definition worker.ajp13.* , ajp13 is the worker name you specified earlier in the httpd.conf.

As a last step, stop and restart the Apache HTTPd to ensure these changes are loaded.

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Testing

For testing this configuration make sure both Geronimo and HTTPd are up and running.

Check Geronimo connectivity by accessing http://localhost:8080/console , you should see the Geronimo Administration Console.
Check HTTPd connectivity by accessing http://localhost , you should see the Apache HTTPd welcome page.
Check the HTTPd - Geronimo request forwarding by accessing http://localhost/console/ , you shoud be redirected to the Geronimo Administration Console. Note at the end of the URL there is a "/", failing to include this / will result in a Not Found error triggered by the Jakarta Tomcat Connector module.

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