Intro

I’m working on a Java web application deployed as a WAR via Apache Tomcat. The application settings are stored in a properties file deployed as a resource within the WAR. A PropertyPlaceholderConfigurer loads this properties file in order to configure bean instances.

Deployment Issues

Initially I used a custom deploy script executing via SSH on a successful Jenkins build. (Yes, I know I should’ve been using capistrano or fabric.) This caused an issue when I went to deploy the application using Chef.

There is an application_java cookbook that makes it easy to deploy WAR-based applications. Unfortunately, the way the properties are packaged with the WAR, I was using a hacky work-around to create the properties using a template resource after the application was deployed and exploded to the webapps directory.

Using a context.xml file

The way that it seems the application_java cookbook wants you to specify app settings is via a context.xml file. A Tomcat context provides two methods of passing variables: context parameters and environment entries. I needed to use one of these methods to pass in the location of the properties file used to configure the application. (The application cookbook family encourages storing configuration in the application’s shared deploy directory.) I found a useful article on StackOverflow 1, but I had to wade through several other references to figure it out completely. Here are the steps I had to take, laid out explicitly.

Configuring the Configuration

Here’s what I had to do:

1. Create an env-entry for variable CONFIG_PATH in the application’s web.xml.
2. Create an Environment element for variable CONFIG_PATH in the application’s context.xml. This is the file that will be used to configure the application using Chef. Make sure the value begins with file: or you’ll get an error like “Could not open ServletContext resource”
3. Add jee namespace to my beans.xml 2

4. Add an entry to perform a JNDI lookup in my beans.xml:

   <jee:jndi-lookup 
     id="beanConfigPath" 
     jndi-name="CONFIG_PATH"/>
   

5. In my beans.xml PropertyPlaceholderConfigurer entry, reference the bean above:

   <bean id="propertyConfigurer" 
     class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
     <property name="location" 
       ref="beanConfigPath" />
   </bean>
   

Conclusion

In retrospect, it may have been easy to try to use a context parameter instead. I also had not heard of JNDI before I worked on this issue, so that’s another topic I need to look into. Still in the works is making sure I can specify the location of a logback.xml file when I deploy via Chef. Right now I’m looking into using the Loader element of the context.xml in order to add the application’s shared directory to the classpath.