Converting Rails 2.3 to Rails 4.0 environment.rb - ruby-on-rails-4

Question

I have an application that runs fine under Rails 2.3.2.
I'm trying to upgrade it to Rails 4.0, using nginx and unicorn.
My config/environment.rb has these lines that don't work:
Rails::Initializer.run do |config|
config.load_paths += %W( #{RAILS_ROOT}/vendor/gems/ #{RAILS_ROOT}/app/exceptions/ )
config.action_controller.session = { :session_key => "my_app", :secret => "c4c6eee57d9af4f2e1a9c56a49d974b7" }
config.gem "mocha", :version => '>=0.9.4'
The error message I get in unicorn.log is
ERROR -- : uninitialized constant Rails (NameError)
/home/art/config/environment.rb:70:in `<top (required)>'
and line 70 is the " Rails::Initializer.run do |config|" line above.
I guess these things have been moved out into some initializer file somewhere?
I guess bundler now handle gem versions, so I should just move the "config.gem... :version ..." lines into my Gemfile?
And where should I set session_key?
Thanks for any advice.

Answer 1

in the new Rails require the application.rb file:
# Load the Rails application.
require File.expand_path('../application', __FILE__)
In the application.rb require rails:
require File.expand_path('../boot', __FILE__)
require 'rails/all'
# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)
usually the session_key is in a new initializer (under initializers folder - look here)
anyway try to run rake rails:update it might help you change some stuff,
or create new rails project and start to copy things from there.