The Java platform supports two kinds of deployment: binary using default tomcat server or code deployment.

You can send a jar file, and java platform will run it with default Procfile and tomcat7. Default procfile starts with:

% cat Procfile
web: /var/lib/tsuru/java/start-tomcat

You can set JAVA_MAX_MEMORY enviroment variable to set amount memory to run tomcat, if you don't it will start with 128MB.

If you just run a tsuru app-deploy of your code, tsuru will try to download all of your dependencies using maven and build your application.