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
   

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2. http://fight.robotlikes.com
   2
   

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3. What Is
   Rack?
   3
   

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5. 5
   x
   browser server rack
   -----
   ------
   ---
   ----
   rails
   

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6. Why Rack?
   6
   

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7. 7
   Speed
   Simplicity
   Reuse
   

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8. Show Me
   The Code!?
   8
   

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9. 9
   # config.ru
   class Application
   def call(env)
   [200, {}, ["Good enough"]]
   end
   end
   run Application.new
   

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10. 10
    # config.ru
    class Application
    def call(env)
    [200, {}, ["Good enough"]]
    end
    end
    run Application.new
    

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11. 11
    # config.ru
    class Application
    def call(env)
    [200, {}, ["Good enough"]]
    end
    end
    run Application.new
    

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12. 12
    # config.ru
    class Application
    def call(env)
    [200, {}, ["Good enough"]]
    end
    end
    run Application.new
    

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13. 13
    # config.ru
    class Application
    def call(env)
    [200, {}, ["Good enough"]]
    end
    end
    run Application.new
    

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14. 14
    # config.ru
    class Application
    def call(env)
    [200, {}, ["Good enough"]]
    end
    end
    run Application.new
    

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15. 15
    # config.ru
    class Application
    def call(env)
    [200, {}, ["Good enough"]]
    end
    end
    run Application.new
    

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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
    

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18. 18
    $ terminal
    $ curl http://localhost:9292
    Good enough
    

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19. Rack::Test
    19
    

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20. 20
    # Gemfile
    gem "rack"
    gem "rack-test"
    

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21. 21
    # test/test_helper.rb
    require "minitest/autorun"
    require "rack/test"
    

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22. 22
    # app_test.rb
    class ApplicationTest < Minitest::Test
    include Rack::Test::Methods
    def app
    Application.new
    end
    # ...
    end
    

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23. 23
    # app_test.rb
    class ApplicationTest < Minitest::Test
    include Rack::Test::Methods
    def app
    Application.new
    end
    # ...
    end
    

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24. 24
    # app_test.rb
    class ApplicationTest < Minitest::Test
    include Rack::Test::Methods
    def app
    Application.new
    end
    # ...
    end
    

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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
    

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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
    

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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
    

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28. Think About
    The
    Environment!
    28
    

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29. 29
    # config.ru
    class Application
    def call(env)
    [200, {}, ["Good enough"]]
    end
    end
    run Application.new
    

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30. 30
    # config.ru
    class Application
    def call(env)
    [200, {}, ["Good enough"]]
    end
    end
    run Application.new
    

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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"=> #,
    # ...
    }
    

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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"=> #,
    # ...
    }
    

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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"=> #,
    # ...
    }
    

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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"=> #,
    # ...
    }
    

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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
    

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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
    

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37. Routing
    37
    

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38. 38
    Frameworks help!
    

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39. 39
    # config.ru
    class Status
    def call(env)
    # ...
    end
    end
    map "/status" do run Status.new end
    map "/" do run Application.new end
    

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40. 40
    # config.ru
    class Status
    def call(env)
    # ...
    end
    end
    map "/status" do run Status.new end
    map "/" do run Application.new end
    

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41. 41
    # config.ru
    class Status
    def call(env)
    # ...
    end
    end
    run Rack::URLMap.new(
    "/status" => Status.new,
    "/" => Application.new
    )
    

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42. Rack::Request
    42
    

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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
    

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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
    

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45. 45
    Isn't there an easier
    way!?
    

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46. 46
    Frameworks help!
    

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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
    

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48. 48
    $ terminal
    $ curl http://localhost:9292/bot/1
    <--[1]-->
    

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49. GET
    49
    

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50. POST
    50
    

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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
    

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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
    

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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
    

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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
    

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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
    

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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
    

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57. 57
    $ terminal
    $ curl -X POST http://localhost:9292/bot/2
    --data "\[*]/"
    Wrote bot 2
    

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58. 58
    $ terminal
    $ curl -X POST http://localhost:9292/bot/2
    --data "\[*]/"
    Wrote bot 2
    $ curl http://localhost:9292/bot/2
    \[*]/
    

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59. Rack::Response
    59
    

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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
    

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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
    

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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
    

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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
    

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64. 64
    $ pry
    > response.finish
    [200,
    {"Content-Length"=>"11"},
    #]
    

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65. 65
    $ pry
    > response.finish
    [200,
    {"Content-Length"=>"11"},
    #]
    

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66. Middleware
    66
    

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67. 67
    # config.ru
    require 'app'
    use Middleware
    run Application.new
    

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68. 68
    # config.ru
    require 'app'
    use Middleware
    run Application.new
    

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69. 69
    middleware middleware
    -----
    ------
    ---
    ----
    app
    -----
    ------
    ---
    ----
    -----
    ------
    ---
    ----
    call() call() call()
    

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70. 70
    # middleware.rb
    class Middleware
    def initialize(app, _opts={})
    @app = app
    end
    def call(env)
    @app.call(env)
    end
    end
    

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71. 71
    # middleware.rb
    class Middleware
    def initialize(app, _opts={})
    @app = app
    end
    def call(env)
    @app.call(env)
    end
    end
    

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72. 72
    # middleware.rb
    class Middleware
    def initialize(app, _opts={})
    @app = app
    end
    def call(env)
    @app.call(env)
    end
    end
    

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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
    

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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
    

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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
    

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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
    

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77. 77
    middleware
    -----
    ------
    ---
    ----
    app
    -----
    ------
    ---
    ----
    call()
    nope!
    

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78. 78
    $ terminal
    $ curl http://localhost:9292/bot/1
    FORBIDDEN! BEEP
    

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79. 79
    $ terminal
    $ curl http://localhost:9292/bot/1
    FORBIDDEN! BEEP
    $ curl -H "X-Api-Key: beep"
    http://localhost:9292/bot/1
    <--[1]-->
    

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80. 80
    Rack::Static
    Rack::Session::*
    Rack::ShowExceptions
    Rack::Reloader
    

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81. Frameworks
    81
    

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82. 82
    middleware middleware
    -----
    ------
    ---
    ----
    rails
    -----
    ------
    ---
    ----
    call() call() call()
    

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83. 83
    # config/routes.rb
    Rails.application.routes.draw do
    mount RackApplication.new, at: "/api"
    end
    

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84. 84
    # config/application.rb
    class Application < Rails::Application
    config.middleware.use RackMiddleware
    config.middleware.insert_after
    Rack::Static,
    AnotherMiddleware
    end
    

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85. 85
    # config/application.rb
    class Application < Rails::Application
    config.middleware.use RackMiddleware
    config.middleware.insert_after
    Rack::Static,
    AnotherMiddleware
    end
    

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86. 86
    # config/application.rb
    class Application < Rails::Application
    config.middleware.use RackMiddleware
    config.middleware.insert_after
    Rack::Static,
    AnotherMiddleware
    end
    

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87. 87
    middleware middleware
    -----
    ------
    ---
    ----
    rails
    -----
    ------
    ---
    ----
    call() call() call()
    

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88. 88
    middleware middleware
    ----
    ----
    ---
    ----
    rails
    ----
    ----
    ---
    ----
    middleware
    --
    ---
    --
    ---
    

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89. 89
    middleware middleware
    -----
    ------
    ---
    ----
    sinatra
    -----
    ------
    ---
    ----
    call() call() call()
    

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90. 90
    # sinatra_app.rb
    class Application < Sinatra::Base
    get "/" do
    [200, {}, ["Wut!?"]]
    end
    end
    

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91. 91
    # sinatra_app.rb
    class Application < Sinatra::Base
    get "/" do
    [200, {}, ["Wut!?"]]
    end
    end
    

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92. https://bit.ly/rack-apps
    What, Why, and How
    Request and Response
    Middleware
    Frameworks
    92
    ??
    

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