Rack - O hério oculto de aplicações web Rub.pdf

Um overview da interface Rack, destacando sua importância e como ele atua discretamente, mas com grande impacto. Exploraremos conceitos-chave como modularização e adaptabilidade, demonstrando como o Rack incorpora esses princípios de forma eficaz. Exemplos práticos, estrutura básica e conceitos como Middlewares, fluxo de execução e etc.

1. Rack
O Herói oculto das aplicações web em
Ruby
@aristotelesbr

2. RACK

3. •What is it for?
•Internal Operation
•Details such as: Lifecycle,
Execution
•What can be done?
•When to use?
•The impacts of decisions
•The importance of
knowledge

4. About me
•Software developer
•Ruby
•Photo
•Blog
•Lenna & Lolla
@aristotelesbr

5. RACK?

6. “Rack provide a minimal, modular,
and adaptable interface for
developing web applications in Ruby”

7. •Essential features
•Bridge to server
•Simple to understand
•Light
•Performance

8. “Rack provide a minimal, modular,
and adaptable interface for
developing web applications in Ruby”

9. proc do |_env|
▏ [
▏ ▏ 200,
▏ ▏ { 'content-type' => 'text/html' },
▏ ▏ ['Olá, mundo! Esta é uma aplicação Rack!']
▏ ]
end

10. proc do |_env|
▏ [
▏ ▏ 200,
▏ ▏ { 'content-type' => 'text/html' },
▏ ▏ ['Olá, mundo! Esta é uma aplicação Rack!']
▏ ]
end

11. proc do |_env|
▏ [
▏ ▏ 200,
▏ ▏ { 'content-type' => 'text/html' },
▏ ▏ ['Olá, mundo! Esta é uma aplicação Rack!']
▏ ]
end

12. proc do |_env|
▏ [
▏ ▏ 200,
▏ ▏ { 'content-type' => 'text/html' },
▏ ▏ ['Olá, mundo! Esta é uma aplicação Rack!']
▏ ]
end

13. How to run?

14. config.ru

15. $ bundle add rack
$ bundle add rackup
$ bundle add webrick

17. !
!

18. !

19. ~/Projects/examples/rack_examples ❯ bundle exec rackup
[2024-01-26 12:35:28] INFO WEBrick 1.8.1
[2024-01-26 12:35:28] INFO ruby 3.3.0 (2023-12-25) [arm64-
darwin23]
[2024-01-26 12:35:28] INFO WEBrick::HTTPServer#start: pid=38777
port=9292

20. ~/Projects/examples/rack_examples ❯ bundle exec rackup
[2024-01-26 12:35:28] INFO WEBrick 1.8.1
[2024-01-26 12:35:28] INFO ruby 3.3.0 (2023-12-25) [arm64-
darwin23]
[2024-01-26 12:35:28] INFO WEBrick::HTTPServer#start: pid=38777
port=9292

21. ~/Projects/examples/rack_examples ❯ bundle exec rackup
[2024-01-26 12:35:28] INFO WEBrick 1.8.1
[2024-01-26 12:35:28] INFO ruby 3.3.0 (2023-12-25) [arm64-
darwin23]
[2024-01-26 12:35:28] INFO WEBrick::HTTPServer#start: pid=38777
port=9292

24. (What happens
internally? ")

26. ❌

27. require 'rack'
app = proc do |env|
▏ [
▏ ▏ 200,
▏ ▏ { 'content-type' => 'text/html' },
▏ ▏ […]
▏ ]
end
run app

28. require 'rack'
app = proc do |env|
▏ [
▏ ▏ 200,
▏ ▏ { 'content-type' => 'text/html' },
▏ ▏ [env.inspect]
▏ ]
end
run app
!

30. $

34. class MyApplication
▏ def call(env)
▏ ▏ request = Rack::Request.new(env)
▏ ▏ if request.get? && request.path == '/'
▏ ▏ ▏ [200, { 'content-type' => 'text/plain' }, ['Home Page']]
▏ ▏ elsif request.post? && request.path == '/submit'
▏ ▏ ▏ [200, { 'content-type' => 'text/plain' }, ['Dados
recebidos']]
▏ ▏ else
▏ ▏ ▏ [404, { 'content-type' => 'text/plain' }, ['Página não
encontrada’]]
▏ ▏ end
▏ end
end

35. class MyApplication
▏ def call(env)
▏ ▏ response = Rack::Response.new
▏ ▏ response.write "Olá, mundo!"
▏ ▏ response.status = 200
▏ ▏ response['content-type'] = 'text/plain'
▏ ▏ response.finish
▏ end
end

36. ✅
⚠

37. “Rack provide a minimal, modular,
and adaptable interface for
developing web applications in Ruby”

38. “Anatomy" of a
Middleware

39. class GurupiMiddleware
▏ def initialize(app)
▏ ▏ @app = app
▏ end
▏ def call(env)
▏ ▏ status, headers, body = @app.call(env)
▏ ▏ headers[‘x-gurupi'] = 'GURUPI'
▏ ▏ [status, headers, body]
▏ end
end

40. LIFO
Last in, First Out.

41. class GurupiMiddleware
▏ def initialize(app)
▏ ▏ @app = app
▏ end
▏ def call(env)
▏ ▏ status, headers, body = @app.call(env)
▏ ▏ headers['x-gurupi'] = 'GURUPI'
▏ ▏ [status, headers, body]
▏ end
end

42. class GurupiMiddleware
▏ def initialize(app)
▏ ▏ @app = app
▏ end
▏ def call(env)
▏ ▏ status, headers, body = @app.call(env)
▏ ▏ headers['x-gurupi'] = 'GURUPI'
▏ ▏ [status, headers, body]
▏ end
end '

44. How to use?

45. use GurupiMiddleware

46. require 'rack'
require_relative 'gurupi_middleware '
app = proc do |env|
▏ [
▏ ▏ 200,
▏ ▏ { 'content-type' => 'text/html' },
▏ ▏ [“Hello GURUPI"]
▏ ]
end
use GurupiMiddleware
run app
!
!

47. !

48. require 'rack'
require_relative 'gurupi_middleware '
app = proc do |env|
▏ [
▏ ▏ 200,
▏ ▏ { 'content-type' => 'text/html' },
▏ ▏ [env.inspect]
▏ ]
end
use GurupiMiddleware
use MiddlewareA
use MiddlewareB
…
run app
!

49. (⚠)

51. ⏱

52. ⏱

53. ⏱

54. ✅

55. ✅

56. ✅

57. ✅

58. Production

59. ⚠

60. “Rack provide a minimal, modular,
and adaptable interface for
developing web applications in Ruby”

62. $ bundle add puma

63. require ‘rack’
require ‘puma’
app = proc do |_env|
▏ [
▏ ▏ 200,
▏ ▏ { 'content-type' => 'text/html' },
▏ ▏ ['Hello GURUPI']
▏ ]
end
run app

67. What is Rack?
•Minimal ✅
•Modular ✅
•Adaptable ✅

68. Let's practice?

69. https://github.com/aristotelesbr/rating_app

71. https://github.com/aristotelesbr/rating_app

72. Conclusion

73. Is it possible to use
Ruby without Rails?

74. Is it possible When to
use Ruby without Rails?

75. Rails $

76. "Rack" $

77. "There is no free lunch”

78. ~/Projects/examples/example_app main* ❯ rails middleware
use ActionDispatch::HostAuthorization
use Rack::Sendfile
use ActionDispatch::Static
use ActionDispatch::Executor
use ActionDispatch::ServerTiming
use ActiveSupport::Cache::Strategy::LocalCache::Middleware
use Rack::Runtime
use Rack::MethodOverride
use ActionDispatch::RequestId
use ActionDispatch::RemoteIp
use Sprockets::Rails::QuietAssets
use Rails::Rack::Logger
use ActionDispatch::ShowExceptions
use WebConsole::Middleware
use ActionDispatch::DebugExceptions
use ActionDispatch::ActionableExceptions
use ActionDispatch::Reloader
use ActionDispatch::Callbacks
use ActiveRecord::Migration::CheckPending
use ActionDispatch::Cookies
use ActionDispatch::Session::CookieStore
use ActionDispatch::Flash
use ActionDispatch::ContentSecurityPolicy::Middleware
use ActionDispatch::PermissionsPolicy::Middleware
use Rack::Head
use Rack::ConditionalGet
use Rack::ETag
use Rack::TempfileReaper
run ExampleApp::Application.routes

79. ~/Projects/examples/example_app main* ❯ bundle init
=> Gemfile
)

80. Where is Rack used?

81. Syro

82. Questions?

84. •https://github.com/aristotelesbr
•https://www.linkedin.com/in/aristotelescoutinho
•https://ruby.social/@aristotelesbr