How to provide a context configuration for a web application in Tomcat?

Question

I have a web application that relies on some resources and parameters to be configured after it is installed, like a JDBC connection.

What I have come up with is pro

Answer 1

The solution is simple: don't put configuration in your context.xml.

Here is a solution that we use (which works well for a number of diverse external customers):

We have a single war which will be used in multiple environments, webapp.war. We have three environments, development, integration and production. Integration and production are at the customer site. We don't know passwords and file paths for the client integration and production sites.

We use a combination of two things: JNDI lookup for database stuff and external properties files.

In the context.xml that is delivered in the war, we have a ResourceLink

This gives a reference to a globally defined data source, which is defined in the server.xml for Tomcat.

So the database details can be changed by editing the server.xml without changing the webapp.war. Crucially, this only needs to be done once for each server, not at redeploy.

In our spring configuration, to define the dataSource we have:

For other properties, we have a global application.properties file which is delivered along with the webapp.war, but is not part of the war. This is referenced by a -D on the command line to start Tomcat. -Duk.co.farwell.webapp.applicationDir="/usr/xxx/fff". We pick up the definition and read the properties file. The database stuff could be done this way as well, but we'd lose the pooling done by Tomcat.

Another thing: we don't have to rebuild if servers are moved, or if machines are changed for some reason. This is a matter for the customer and their infrastructure people.