database_configuration

# File railties/lib/rails/application/configuration.rb, line 436
      def database_configuration
        path = paths["config/database"].existent.first
        yaml = Pathname.new(path) if path

        config = if yaml&.exist?
          loaded_yaml = ActiveSupport::ConfigurationFile.parse(yaml)
          if (shared = loaded_yaml.delete("shared"))
            loaded_yaml.each do |env, config|
              if config.is_a?(Hash) && config.values.all?(Hash)
                if shared.is_a?(Hash) && shared.values.all?(Hash)
                  config.map do |name, sub_config|
                    sub_config.reverse_merge!(shared[name])
                  end
                else
                  config.map do |name, sub_config|
                    sub_config.reverse_merge!(shared)
                  end
                end
              else
                config.reverse_merge!(shared)
              end
            end
          end
          Hash.new(shared).merge(loaded_yaml)
        elsif ENV["DATABASE_URL"]
          # Value from ENV['DATABASE_URL'] is set to default database connection
          # by Active Record.
          {}
        else
          raise "Could not load database configuration. No such file - #{paths["config/database"].instance_variable_get(:@paths)}"
        end

        config
      rescue => e
        raise e, "Cannot load database configuration:\n#{e.message}", e.backtrace
      end