# File lib/rack/server.rb, line 156
156:     def app
157:       @app ||= begin
158:         if !::File.exist? options[:config]
159:           abort "configuration #{options[:config]} not found"
160:         end
161: 
162:         app, options = Rack::Builder.parse_file(self.options[:config], opt_parser)
163:         self.options.merge! options
164:         app
165:       end
166:     end