Getting the Hostname or IP in Ruby on Rails

I'm in the process of maintaining a Ruby on Rails app and am looking for an easy way to find the hostname or IP address of the box I'm on (since it's a VM and new instances may have different hostnames or IP addresses). Is there a quick and easy way to do this in Ruby on Rails? Edit: The answer below is correct but the clarification Craig provided is useful (see also provided link in answer): The