Updated: Rails3 Custom Environment Variables

A while back, I wrote a blog post on adding custom environment variables to Rails3.

This has gotten much easier with a change made by Jose Valim back in March.

The change allows you to create your own custom configuration variables like so:

# config/environments/development.rb
Demo::Application.configure do
  [...]
  config.json_url = "http://www.domain.com"
  [...]
end

# config/environments/test.rb
Demo::Application.configure do
  [...]
  config.json_url = "http://test.domain.com"
  [...]
end

This allows you to add any configuration variables you want to your Rails app. What if you have a bunch of configuration values? You don’t want to pollute your config.* namespace. Wouldn’t it be helpful to have config.my_app.json_url and config.my_app.other_url?

That’s easy enough:

# config/environments/application.rb
Demo::Application.configure do
  config.my_app = ActiveSupport::OrderedOptions.new
end

# config/environments/development.rb
Demo::Application.configure do
  [...]
  config.my_app.json_url = "http://www.domain.com"
  [...]
end

# config/environments/test.rb
Demo::Application.configure do
  [...]
  config.my_app.json_url = "http://test.domain.com"
  [...]
end

Now you can do the following in the Rails console:

$ rails console
>> Demo::Application.config.my_app.json_url
"http://www.domain.com"
>>

$ rails console test
>> Demo::Application.config.my_app.json_url
"http://test.domain.com"
>>

Now your Rails application will have access to all the configuration you need.