Hi, Rack team,
I have created a rackup option -b/--builder, which is passed with Rack::Builder's build script.
This patch allows you a command like below, and will boot up the file directory server, without any config.ru file.
bundle exec rackup -b "run Rack::Directory.new '.'"
I intend this option to be just used as plackup's one-liner option -e.
How do you think?
Extract Builder.new_from_string from Builder.parse_file
Add a rackup option for one-liner rack app server