[logback-user] Context configuration during webapp loading

[Eric Schwarzenbach]

I'm trying to use variable substitution for my log file names, using the 
webapp / context name. (My use case is not literally a shared 
configuration, but two webapps deployed using copies of the same war 
with different names...so they each have their own logback.xml, though 
they are identical). I'm using the example on 
http://logback.qos.ch/faq.html#sharedConfiguration as my basis, and 
while it is working, my webapp ends up creating two log files.

First it creates one called application-name_IS_UNDEFINED.log with some 
of the first messages logged during startup, and then foo.log (where foo 
is the app name) with all subsequent messages. So it seems to me that 
the contextInitialized method of ServletContextListener isn't early 
enough, and that the default logback config is initializing earlier. 
This is using Tomcat 7, and Java 7.

How can I either hook into the earlier initialization or replace it? 
Where does that initialization happen? Is that static code?

Thanks,

Eric