Ruby Rack - mounting a simple web server that reads index.html as default

I think that you are missing the the rackup command. Here is how it is used:

rackup config.ru

This is going to run your rack app on port 9292 using webrick. You can read "rackup --help" for more info how you can change these defaults.

About the app that you want to create. Here is how I think it should look like:

# This is the root of our app@root = File.expand_path(File.dirname(__FILE__))run Proc.new { |env|  # Extract the requested path from the request  path = Rack::Utils.unescape(env['PATH_INFO'])  index_file = @root + "#{path}/index.html"  if File.exists?(index_file)    # Return the index    [200, {'Content-Type' => 'text/html'}, File.read(index_file)]    # NOTE: using Ruby >= 1.9, third argument needs to respond to :each    # [200, {'Content-Type' => 'text/html'}, [File.read(index_file)]]  else    # Pass the request to the directory app    Rack::Directory.new(@root).call(env)  end}

I ended up on this page looking for a one liner...

If all you want is to serve the current directory for a few one-off tasks, this is all you need:

ruby -run -e httpd . -p 5000

Details on how it works: http://www.benjaminoakes.com/2013/09/13/ruby-simple-http-server-minimalist-rake/

You can do this using Rack::Static

map "/foo" do  use Rack::Static,     :urls => [""], :root => File.expand_path('bar'), :index => 'index.html'  run lambda {|*|}end