Rack 'em, Stack 'em, Web Apps

While Rails is the most common Ruby web framework, it’s not the only option. Rack is a simple, elegant HTTP library, ideal for microservices and high performance applications.

In this talk, you’ll see Rack from top to bottom. Starting from the simplest app, we’ll grow our code into a RESTful HTTP API. We’ll test our code, write reusable middleware, and dig through what Rack provides out of the box. Throughout, we’ll balance when Rack is a good fit, and when larger tools are needed.

If you’ve heard of Rack but wondered where it fits in the Ruby web stack, here’s your chance!

Transcript

1. Rack 'em Stack 'em Web Apps @jasonrclark art by asher clark
2. http://fight.robotlikes.com 2
3. What Is Rack? 3
5. 5 x browser server rack ----- ------ --- ---- rails
6. Why Rack? 6
7. 7 Speed Simplicity Reuse
8. Show Me The Code!? 8
9. 9 # config.ru class Application def call(env) [200, {}, ["Good enough"]] end end run Application.new
10. 10 # config.ru class Application def call(env) [200, {}, ["Good enough"]] end end run Application.new
11. 11 # config.ru class Application def call(env) [200, {}, ["Good enough"]] end end run Application.new
12. 12 # config.ru class Application def call(env) [200, {}, ["Good enough"]] end end run Application.new
13. 13 # config.ru class Application def call(env) [200, {}, ["Good enough"]] end end run Application.new
14. 14 # config.ru class Application def call(env) [200, {}, ["Good enough"]] end end run Application.new
15. 15 # config.ru class Application def call(env) [200, {}, ["Good enough"]] end end run Application.new
16. 16 $ terminal $ rackup [2017-04-17] INFO WEBrick 1.3.1 [2017-04-17] INFO ruby 2.4.1 [2017-04-17] INFO WEBrick::HTTPServer#start: pid=32555 port=9292
18. 18 $ terminal $ curl http://localhost:9292 Good enough
19. Rack::Test 19
20. 20 # Gemfile gem "rack" gem "rack-test"
21. 21 # test/test_helper.rb require "minitest/autorun" require "rack/test"
22. 22 # app_test.rb class ApplicationTest < Minitest::Test include Rack::Test::Methods def app Application.new end # ... end
23. 23 # app_test.rb class ApplicationTest < Minitest::Test include Rack::Test::Methods def app Application.new end # ... end
24. 24 # app_test.rb class ApplicationTest < Minitest::Test include Rack::Test::Methods def app Application.new end # ... end
25. 25 # app_test.rb class ApplicationTest < Minitest::Test def test_its_good_enough get "/" assert last_response.ok? assert_equal "Good enough", last_response.body end end
26. 26 # app_test.rb class ApplicationTest < Minitest::Test def test_its_good_enough get "/" assert last_response.ok? assert_equal "Good enough", last_response.body end end
27. 27 # app_test.rb class ApplicationTest < Minitest::Test def test_its_good_enough get "/" assert last_response.ok? assert_equal "Good enough", last_response.body end end
28. Think About The Environment! 28
29. 29 # config.ru class Application def call(env) [200, {}, ["Good enough"]] end end run Application.new
30. 30 # config.ru class Application def call(env) [200, {}, ["Good enough"]] end end run Application.new
31. 31 # env { "REMOTE_ADDR"=>"::1", "REQUEST_METHOD"=>"GET", "REQUEST_URI"=>"http://localhost/bot", "PATH_INFO"=>"/bot", "QUERY_STRING"=>"", "HTTP_USER_AGENT"=>"Mozilla/5.0 (Mac)", "rack.input"=> #<Rack::Lint::InputWrapper>, # ... }
32. 32 # env { "REMOTE_ADDR"=>"::1", "REQUEST_METHOD"=>"GET", "REQUEST_URI"=>"http://localhost/bot", "PATH_INFO"=>"/bot", "QUERY_STRING"=>"", "HTTP_USER_AGENT"=>"Mozilla/5.0 (Mac)", "rack.input"=> #<Rack::Lint::InputWrapper>, # ... }
33. 33 # env { "REMOTE_ADDR"=>"::1", "REQUEST_METHOD"=>"GET", "REQUEST_URI"=>"http://localhost/bot", "PATH_INFO"=>"/bot", "QUERY_STRING"=>"", "HTTP_USER_AGENT"=>"Mozilla/5.0 (Mac)", "rack.input"=> #<Rack::Lint::InputWrapper>, # ... }
34. 34 # env { "REMOTE_ADDR"=>"::1", "REQUEST_METHOD"=>"GET", "REQUEST_URI"=>"http://localhost/bot", "PATH_INFO"=>"/bot", "QUERY_STRING"=>"", "HTTP_USER_AGENT"=>"Mozilla/5.0 (Mac)", "rack.input"=> #<Rack::Lint::InputWrapper>, # ... }
35. 35 # config.ru class Application def call(env) if env["PATH_INFO"] == "/bot" [403, {}, ["Beep beep intruder"]] else [200, {}, ["Good enough"]] end end end
36. 36 # config.ru class Application def call(env) if env["PATH_INFO"] == "/bot" [403, {}, ["Beep beep intruder"]] else [200, {}, ["Good enough"]] end end end
37. Routing 37
38. 38 Frameworks help!
39. 39 # config.ru class Status def call(env) # ... end end map "/status" do run Status.new end map "/" do run Application.new end
40. 40 # config.ru class Status def call(env) # ... end end map "/status" do run Status.new end map "/" do run Application.new end
41. 41 # config.ru class Status def call(env) # ... end end run Rack::URLMap.new( "/status" => Status.new, "/" => Application.new )
42. Rack::Request 42
43. 43 # app.rb class Application def call(env) request = Rack::Request.new(env) if request.path_info == "/bot" [403, {}, ["Beep intruder"]] else [200, {}, ["Good enough"]] end end end
44. 44 # app.rb class Application def call(env) request = Rack::Request.new(env) if request.path_info.match %r{/bot/(\d+)} [403, {}, ["Beep intruder on #{$1}"]] else [200, {}, ["Good enough"]] end end end
45. 45 Isn't there an easier way!?
46. 46 Frameworks help!
47. 47 # app.rb class Application def call(env) request = Rack::Request.new(env) if request.path_info.match %r{/bot/(\d+)} bot = Database.find($1) [200, {}, [bot.to_s]] else # ... end end end
48. 48 $ terminal $ curl http://localhost:9292/bot/1 <--[1]-->
49. GET 49
50. POST 50
51. 51 # app.rb if request.path_info.match %r{/bot/(\d+)} if request.get? bot = Database.find($1) [200, {}, [bot.to_s]] elsif request.post? bot = request.body.read Database.save($1, bot) [200, {}, ["Wrote bot #{$1}"]] end end
52. 52 # app.rb if request.path_info.match %r{/bot/(\d+)} if request.get? bot = Database.find($1) [200, {}, [bot.to_s]] elsif request.post? bot = request.body.read Database.save($1, bot) [200, {}, ["Wrote bot #{$1}"]] end end
53. 53 # app.rb if request.path_info.match %r{/bot/(\d+)} if request.get? bot = Database.find($1) [200, {}, [bot.to_s]] elsif request.post? bot = request.body.read Database.save($1, bot) [200, {}, ["Wrote bot #{$1}"]] end end
54. 54 # app.rb if request.path_info.match %r{/bot/(\d+)} if request.get? bot = Database.find($1) [200, {}, [bot.to_s]] elsif request.post? bot = request.body.read Database.save($1, bot) [200, {}, ["Wrote bot #{$1}"]] end end
55. 55 # app.rb if request.path_info.match %r{/bot/(\d+)} if request.get? bot = Database.find($1) [200, {}, [bot.to_s]] elsif request.post? bot = request.body.read Database.save($1, bot) [200, {}, ["Wrote bot #{$1}"]] end end
56. 56 # app.rb if request.path_info.match %r{/bot/(\d+)} if request.get? bot = Database.find($1) [200, {}, [bot.to_s]] elsif request.post? bot = request.body.read Database.save($1, bot) [200, {}, ["Wrote bot #{$1}"]] end end
57. 57 $ terminal $ curl -X POST http://localhost:9292/bot/2 --data "\[*]/" Wrote bot 2
58. 58 $ terminal $ curl -X POST http://localhost:9292/bot/2 --data "\[*]/" Wrote bot 2 $ curl http://localhost:9292/bot/2 \[*]/
59. Rack::Response 59
60. 60 # app.rb def call(env) response = Rack::Response.new if #... bot = Database.find($1) response.write(bot.to_s) end response.finish end
61. 61 # app.rb def call(env) response = Rack::Response.new if #... bot = Database.find($1) response.write(bot.to_s) end response.finish end
62. 62 # app.rb def call(env) response = Rack::Response.new if #... bot = Database.find($1) response.write(bot.to_s) end response.finish end
63. 63 # app.rb def call(env) response = Rack::Response.new if #... bot = Database.find($1) response.write(bot.to_s) end response.finish end
64. 64 $ pry > response.finish [200, {"Content-Length"=>"11"}, #<Rack::BodyProxy:0x007f80f0b92ff8...>]
65. 65 $ pry > response.finish [200, {"Content-Length"=>"11"}, #<Rack::BodyProxy:0x007f80f0b92ff8...>]
66. Middleware 66
67. 67 # config.ru require 'app' use Middleware run Application.new
68. 68 # config.ru require 'app' use Middleware run Application.new
69. 69 middleware middleware ----- ------ --- ---- app ----- ------ --- ---- ----- ------ --- ---- call() call() call()
70. 70 # middleware.rb class Middleware def initialize(app, _opts={}) @app = app end def call(env) @app.call(env) end end
71. 71 # middleware.rb class Middleware def initialize(app, _opts={}) @app = app end def call(env) @app.call(env) end end
72. 72 # middleware.rb class Middleware def initialize(app, _opts={}) @app = app end def call(env) @app.call(env) end end
73. 73 # middleware.rb def call(env) req = Rack::Request.new(env) key = req.get_header("HTTP_X_API_KEY") if key == "beep" @app.call(env) else [403, {}, ["FORBIDDEN! BEEP"]] end end
74. 74 # middleware.rb def call(env) req = Rack::Request.new(env) key = req.get_header("HTTP_X_API_KEY") if key == "beep" @app.call(env) else [403, {}, ["FORBIDDEN! BEEP"]] end end
75. 75 # middleware.rb def call(env) req = Rack::Request.new(env) key = req.get_header("HTTP_X_API_KEY") if key == "beep" @app.call(env) else [403, {}, ["FORBIDDEN! BEEP"]] end end
76. 76 # middleware.rb def call(env) req = Rack::Request.new(env) key = req.get_header("HTTP_X_API_KEY") if key == "beep" @app.call(env) else [403, {}, ["FORBIDDEN! BEEP"]] end end
77. 77 middleware ----- ------ --- ---- app ----- ------ --- ---- call() nope!
78. 78 $ terminal $ curl http://localhost:9292/bot/1 FORBIDDEN! BEEP
79. 79 $ terminal $ curl http://localhost:9292/bot/1 FORBIDDEN! BEEP $ curl -H "X-Api-Key: beep" http://localhost:9292/bot/1 <--[1]-->
80. 80 Rack::Static Rack::Session::* Rack::ShowExceptions Rack::Reloader
81. Frameworks 81
82. 82 middleware middleware ----- ------ --- ---- rails ----- ------ --- ---- call() call() call()
83. 83 # config/routes.rb Rails.application.routes.draw do mount RackApplication.new, at: "/api" end
84. 84 # config/application.rb class Application < Rails::Application config.middleware.use RackMiddleware config.middleware.insert_after Rack::Static, AnotherMiddleware end
85. 85 # config/application.rb class Application < Rails::Application config.middleware.use RackMiddleware config.middleware.insert_after Rack::Static, AnotherMiddleware end
86. 86 # config/application.rb class Application < Rails::Application config.middleware.use RackMiddleware config.middleware.insert_after Rack::Static, AnotherMiddleware end
87. 87 middleware middleware ----- ------ --- ---- rails ----- ------ --- ---- call() call() call()
88. 88 middleware middleware ---- ---- --- ---- rails ---- ---- --- ---- middleware -- --- -- ---
89. 89 middleware middleware ----- ------ --- ---- sinatra ----- ------ --- ---- call() call() call()
90. 90 # sinatra_app.rb class Application < Sinatra::Base get "/" do [200, {}, ["Wut!?"]] end end
91. 91 # sinatra_app.rb class Application < Sinatra::Base get "/" do [200, {}, ["Wut!?"]] end end
92. https://bit.ly/rack-apps What, Why, and How Request and Response Middleware Frameworks 92 ??