rbenv

install rbenv and ruby-build

$ git clone https://github.com/sstephenson/rbenv.git ~/.rbenv
$ git clone https://github.com/sstephenson/ruby-build.git ~/.rbenv/plugins/ruby-build

update .bashrc to include (also remove any rvm setup):

export PATH=$HOME/.rbenv/bin:$PATH
eval "$(rbenv init -)"

install ruby and bundler

$ rbenv install 2.0.0-p481
$ rbenv global 2.0.0-p481
$ gem install bundler
$ gem install passenger
$ rbenv rehash

setup a new capistrano installation

$ mv /pub/capistrano /pub/capistrano.bak
$ mkdir -p /pub/capistrano/shared/config
$ ~/bin/update_config.sh

install passenger apache module

$ passenger-install-apache2-module

update /etc/httpd/conf.d/passenger.conf based on the passenger install output

LoadModule passenger_module /home/conan/.rbenv/versions/2.0.0-p481/lib/ruby/gems/2.0.0/gems/passenger-4.0.45/buildout/apache2/mod_passenger.so
<IfModule mod_passenger.c>
PassengerRoot /home/conan/.rbenv/versions/2.0.0-p481/lib/ruby/gems/2.0.0/gems/passenger-4.0.45
PassengerDefaultRuby /home/conan/.rbenv/versions/2.0.0-p481/bin/ruby
</IfModule>

Upgrading ruby

first, update rbenv and ruby-build:

$ cd ~/.rbenv
$ git pull
$ cd plugins/ruby-build
$ git pull

then install a new version of ruby and make it the default:

$ rbenv install 2.1.4
$ rbenv global 2.1.4

make sure to reinstall the bundler and passenger gems, and re-install the passenger module and configuration following the same process above.