Add minimal apps

sinatra.rb

@@ -0,0 +1,48 @@
+begin
+  require "bundler/inline"
+rescue LoadError => e
+  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
+  raise e
+end
+
+require 'yaml'
+compatibility = YAML.load(File.read('compatibility'))
+
+kind = File.basename(__FILE__, '.rb')
+version = ARGV[0] || raise(ArgumentError, 'missing version')
+match = compatibility[kind].select do |e|
+  Gem::Requirement.new(e['version']).satisfied_by?(Gem::Version.new(version))
+end.tap do |m|
+  if m.empty?
+    raise ArgumentError, "unmatched requirement for #{kind}:#{version}"
+  elsif !m.one?
+    raise ArgumentError, "ambiguous version range for #{kind}:#{version}"
+  end
+end.first
+server = ARGV[1] || 'thin'
+
+gemfile(true) do
+  source "https://rubygems.org"
+
+  ruby match['ruby'] if match['ruby']
+
+  gem 'sinatra', "~> #{version}.0"
+  gem server
+
+  match.fetch('gem', []).each do |name, requirement|
+    gem name, requirement
+  end
+end
+
+require 'sinatra/base'
+require 'json'
+
+class App < Sinatra::Base
+  get '/hello/world' do
+    status 200
+    content_type :json
+    body JSON.dump({ hello: :world })
+  end
+end
+
+Rack::Server.new(app: App, Host: '0.0.0.0', Port: 3000).start