A simple rack middleware to debug the request pipeline

config.ru

# Usage example

require "inspect_middleware"
use InspectMiddleware
run GenericSinatraApp

inspect_middleware.rb

class InspectMiddleware
  require "yaml"

  def initialize(app)
    @app = app
  end

  def call(env)
    puts
    puts "-"*80
    puts "Request Pipeline"
    print_middleware_class = lambda do |klass|
      if middleware = klass.instance_variable_get(:@app)
        print "#{middleware.class} -> "
        print_middleware_class.call(middleware)
      else
        puts
        puts "#{klass.class} is a rack endpoint"
        puts
        puts "Class:"
        puts klass.inspect
        puts "-"*80
        puts
      end
    end

    print_middleware_class.call(@app)

    @app.call(env)
  end
end

sample_output.txt

--------------------------------------------------------------------------------
Request Pipeline
Rack::Static -> Rack::Sprockets::Base -> Rack::MobileDetect -> RedirectOnce -> Class -> 
Class is a rack endpoint

Class:
Jelli::UI
--------------------------------------------------------------------------------