class ActiveRecord::DatabaseConfigurations

def find_db_config(env)

the first DatabaseConfig for the environment.
If the application has multiple databases +find_db_config+ will return

Returns a single DatabaseConfig object based on the requested environment. 
def find_db_config(env)
  configurations
    .sort_by.with_index { |db_config, i| db_config.for_current_env? ? [0, i] : [1, i] }
    .find do |db_config|
      db_config.env_name == env.to_s ||
        (db_config.for_current_env? && db_config.name == env.to_s)
    end
end