For Rails, how to access or print out config variables (as experiment or test / debugging)

Most of the Rails config stuff can be accessed through:

Rails.application.config.<your_variable>

With regards to printing out the values of .yml files in config, you'd have to do that yourself becuase Rails will only load up the values for the current environment from database.yml, and any custom yml config files will be just that - custom. Here's one way you could load them all up...

all_configs = []
Dir[Rails.root.join("config/*.yml")].each {|f| all_configs << YAML.load_file(f) }

With regards to settings set in initializers, if it's a Rails config option (such as the session store which you've given as an example), then it will be available through Rails.application.config. If not, (for example configuration for a gem) then you will have to manually find those settings from the gem classes.

You can also use AppName::Application.config (where AppName is the name of your application) to access the Rails::Application::Configuration object.

$ AppName::Application.config == Rails.application.config
true

Like idlefingers pointed out, for newer versions of rails, Rails.application.config.my_variable should get you what you're looking for.

However, if that doesn't work because you're stuck with an older version of Rails (2.3, etc) you can use the ENV constant, like so: ENV['my_variable']