How to deploy rack apps with ruby1.9?

I've been trying to get a simple hello world web app running on Sinatra.

I have the following setup:

• config.ru

  require 'hello.rb'开发者_如何转开发
  run Sinatra::Application
  

• hello.rb

  require "sinatra"
  
  get "/" do
      "Hello World!\n"
  end
  

• Gemfile

  source :rubygems
  gem 'sinatra'
  

This works on my local machine if I run ruby hello.rb, ruby1.9.1 hello.rb or rackup and go to the correct address in my browser. However, this doesn't work when deployed to heroku or if I run rackup1.9.1. I get the following error:

<internal:lib/rubygems/custom_require>:29:in `require': no such file to load -- hello.rb (LoadError)
    from <internal:lib/rubygems/custom_require>:29:in `require'
    from config.ru:1:in `block in <main>'
    from /usr/lib/ruby/1.9.1/rack/builder.rb:46:in `instance_eval'
    from /usr/lib/ruby/1.9.1/rack/builder.rb:46:in `initialize'
    from config.ru:1:in `new'
    from config.ru:1:in `<main>'
    from /usr/lib/ruby/1.9.1/rack/builder.rb:35:in `eval'
    from /usr/lib/ruby/1.9.1/rack/builder.rb:35:in `parse_file'
    from /usr/lib/ruby/1.9.1/rack/server.rb:113:in `app'
    from /usr/lib/ruby/1.9.1/rack/server.rb:189:in `wrapped_app'
    from /usr/lib/ruby/1.9.1/rack/server.rb:155:in `start'
    from /usr/lib/ruby/1.9.1/rack/server.rb:83:in `start'
    from /usr/bin/rackup1.9.1:4:in `<main>'

How can I get this working? I'm guessing config.ru should be different but I don't know what to change.

Try doing

require './hello'

or

require_relative 'hello'

The current directory is not present in the LOAD_PATH by default in Ruby 1.9.2.