Dead easy with a few hiccups if you’re using newer ruby versions. First install the mongrel gem;
> gem install mongrel --pre
The problem I had (and later overcame) was in not adding in the
--pre option into the install – turns out the current stable doesn’t play very well with newer ruby versions. This is likely to be fixed at some point, but this’ll get you through today 🙂
After that, just add the following to your Gemfile;
then just bundle install and rails will use mongrel as the default web server.