Log4jruby is a thin wrapper around the Log4j Logger. It is geared more toward those who are using JRuby to integrate with and build on top of Java code that uses Log4j. The Log4jruby::Logger provides an interface much like the standard ruby Logger. Your ruby loggers are given a .jruby prefix and can be configured along with the loggers for your Java code.
Gemfile gem 'log4jruby', '~> 0.4.0'
install gem install log4jruby