Rack and Middleware

Introduction to Rack and Middleware for YYC Ruby meetup, Feb 2015.

Transcript

1. &
   Rack
   Middleware
   

   View Slide

2. What is Rack?
   

   View Slide

3. Rack is both
   a protocol and a gem
   

   View Slide

4. Created in 2007
   By Christian Neukirchen
   (for reference, Rails was created in 2004)
   

   View Slide

5. MyApp
   Thin
   Unicorn
   Puma
   Passenger
   WEBrick
   Internets
   Rails
   Sinatra
   Lotus
   Server Framework
   Network Application
   RACK
   

   View Slide

6. assert app.respond_to? :call
   status, headers, body = app.call(env)
   assert status.to_i >= 100
   assert headers.is_a? Hash
   assert body.respond_to? :each
   

   View Slide

7. class MyApp
   def call(env)
   [200, {}, ['Hello world']]
   end
   end
   

   View Slide

8. Proc.new do |env|
   [200,{},['Hello world']]
   end
   

   View Slide

9. ->(env) { [200,{},['Hello world']] }
   

   View Slide

10. env and CGI
    

    View Slide

11. curl localhost:8080/hello/world?foo=bar
    

    View Slide

12. GATEWAY_INTERFACE: "CGI/1.1"
    HTTP_ACCEPT: "*/*"
    HTTP_HOST: "localhost:8080"
    HTTP_USER_AGENT: "curl/7.37.1"
    HTTP_VERSION: "HTTP/1.1"
    PATH_INFO: "/hello/world"
    QUERY_STRING: "foo=bar"
    REMOTE_ADDR: "::1"
    REMOTE_HOST: "localhost"
    REQUEST_METHOD: "GET"
    REQUEST_PATH: "/hello/world"
    REQUEST_URI: "http://localhost:8080/hello/world?foo=bar"
    SCRIPT_NAME: ""
    SERVER_NAME: "localhost"
    SERVER_PORT: "8080"
    SERVER_PROTOCOL: "HTTP/1.1"
    SERVER_SOFTWARE: "WEBrick/1.3.1 (Ruby/2.1.3/2014-09-19)"
    

    View Slide

13. GATEWAY_INTERFACE: "CGI/1.1"
    HTTP_ACCEPT: "*/*"
    HTTP_HOST: "localhost:8080"
    HTTP_USER_AGENT: "curl/7.37.1"
    HTTP_VERSION: "HTTP/1.1"
    PATH_INFO: "/hello/world"
    QUERY_STRING: "foo=bar"
    REMOTE_ADDR: "::1"
    REMOTE_HOST: "localhost"
    REQUEST_METHOD: "GET"
    REQUEST_PATH: "/hello/world"
    REQUEST_URI: "http://localhost:8080/hello/world?foo=bar"
    SCRIPT_NAME: ""
    SERVER_NAME: "localhost"
    SERVER_PORT: "8080"
    SERVER_PROTOCOL: "HTTP/1.1"
    SERVER_SOFTWARE: "WEBrick/1.3.1 (Ruby/2.1.3/2014-09-19)"
    

    View Slide

14. GATEWAY_INTERFACE: "CGI/1.1"
    HTTP_ACCEPT: "*/*"
    HTTP_HOST: "localhost:8080"
    HTTP_USER_AGENT: "curl/7.37.1"
    HTTP_VERSION: "HTTP/1.1"
    PATH_INFO: "/hello/world"
    QUERY_STRING: "foo=bar"
    REMOTE_ADDR: "::1"
    REMOTE_HOST: "localhost"
    REQUEST_METHOD: "GET"
    REQUEST_PATH: "/hello/world"
    REQUEST_URI: "http://localhost:8080/hello/world?foo=bar"
    SCRIPT_NAME: ""
    SERVER_NAME: "localhost"
    SERVER_PORT: "8080"
    SERVER_PROTOCOL: "HTTP/1.1"
    SERVER_SOFTWARE: "WEBrick/1.3.1 (Ruby/2.1.3/2014-09-19)"
    

    View Slide

15. rack.errors: #>
    rack.hijack: #@lib/rack/handler/webrick.rb:77 (lambda)>
    rack.hijack?: true
    rack.hijack_io: nil
    rack.input: #
    rack.multiprocess: false
    rack.multithread: true
    rack.run_once: false
    rack.url_scheme: "http"
    rack.version: [1, 3]
    

    View Slide

16. rack.errors: #>
    rack.hijack: #@lib/rack/handler/webrick.rb:77 (lambda)>
    rack.hijack?: true
    rack.hijack_io: nil
    rack.input: #
    rack.multiprocess: false
    rack.multithread: true
    rack.run_once: false
    rack.url_scheme: "http"
    rack.version: [1, 3]
    

    View Slide

17. rack.errors: #>
    rack.hijack: #@lib/rack/handler/webrick.rb:77 (lambda)>
    rack.hijack?: true
    rack.hijack_io: nil
    rack.input: #
    rack.multiprocess: false
    rack.multithread: true
    rack.run_once: false
    rack.url_scheme: "http"
    rack.version: [1, 3]
    

    View Slide

18. middleware
    

    View Slide

19. Handler Middleware Middleware App
    Internets
    

    View Slide

20. Handler Middleware Middleware
    Internets
    Request
    Request
    Request
    Request
    Request
    Internets App
    

    View Slide

21. Handler Middleware Middleware
    Request
    Response
    Response
    Response
    Response
    Internets App
    

    View Slide

22. Handler Middleware
    Internets
    Request
    Request
    Request
    Request
    Internets
    Response
    Response
    Response
    Middleware App
    

    View Slide

23. qux = ->(env){ [200,{},['Hello world']] }
    bar = ->(env){ qux.call(env) }
    foo = ->(env){ bar.call(env) }
    run foo
    

    View Slide

24. class Middleware
    def initialize(app)
    @app = app
    end
    def call(env)
    @app.call(env)
    end
    end
    

    View Slide

25. class Reverse < Middleware
    def call(env)
    status, headers, body = super
    body.each(&:reverse!)
    [status, headers, body]
    end
    end
    use Reverse
    use Reverse
    run ->(env){ [200,{},['Hello world']] }
    

    View Slide

26. Rack::Builder
    and config.ru
    

    View Slide

27. $ rackup config.ru
    

    View Slide

28. if config.end_with?('ru')
    Rack::Builder.new {
    
    }.to_app
    end
    

    View Slide

29. require_relative 'lib/my_app'
    use Rack::CommonLogger
    use Rack::Session::Cookie
    run MyApp.new
    

    View Slide

30. map '/admin' do
    use Authorization::Basic
    run Admin::App.new
    end
    map '/api' do
    use Authorization::Token
    run Api::App.new
    end
    

    View Slide

31. warmup do |app|
    client = Rack::MockRequest.new(app)
    client.get '/cached_resource'
    end
    

    View Slide

32. rackup greeter.rb
    

    View Slide

33. if config.end_with?('rb')
    require config
    app_name = File.basename(config, '.rb')
    app = Object.const_get(app_name.capitalize)
    run app
    end
    

    View Slide

34. class Greeter
    def self.call(env)
    params = Rack::Request.new(env).params
    name = params.fetch('name', 'unknown')
    [200, {}, ["Greetings, #{name}"]]
    end
    end
    

    View Slide

35. # greeter.rb -> Greeter
    # my_app.rb -> My_app
    

    View Slide

36. Request, Response,
    BodyProxy, and Utils
    

    View Slide

37. def call(env)
    request = Rack::Request.new(env)
    request.request_method?
    request.post?
    request.get?
    request.params['query']
    request.update_params['query', 'foobar']
    request.ip
    end
    

    View Slide

38. def call(env)
    response = @app.call(env)
    response = Rack::Response.new(response)
    response['Etag'] = 'abc123'
    response.redirect('/faq')
    response.set_cookie('user_id', 123)
    response.write 'Hello world'
    end
    

    View Slide

39. def call(env)
    status, headers, body = @app.call
    body = BodyProxy.new(body) do
    # Ensure something happens after
    # body.close is called, eg.
    DB.connection.close
    end
    [status, headers, body]
    end
    

    View Slide

40. include Rack::Utils
    parse_query 'foo=bar&foo=qux'
    #=> {'foo' => ['bar','qux']}
    parse_nested_query 'foo[]=bar&foo[]=qux'
    #=> {'foo' => ['bar','qux']}
    parse_nested_query 'foo[x]=bar&foo[y]=qux'
    #=> {'foo' => {'x' => 'bar', 'y' => 'qux'}}
    

    View Slide

41. include Rack::Utils
    build_query {foo: ['bar','qux']}
    #=> 'foo=bar&foo=qux'
    build_nested_query {foo: ['bar', 'qux']}
    #=> 'foo[]=bar&foo[]=qux'
    build_nested_query {foo: {x: 'bar', y: 'qux'}}
    #=> 'foo[x]=bar&foo[y]=qux'
    

    View Slide

42. Callbacks
    Cascade
    Chunked
    CommonCookies
    CommonLogger
    ConditionalGet
    Config
    ContentLength
    ContentType
    Context
    CookieJar
    Cookies
    DeflateStream
    Deflater
    Deflater
    Deflect
    Directory
    ETag
    ErrorWrapper
    Evil
    ExpectationCascade
    File
    ForwardRequest
    GarbageCollector
    GzipStream
    HeaderHash
    HijackWrapper
    HostMeta
    InputWrapper
    InvalidParameterError
    JSONP
    KeySpaceConstrainedParams
    LighttpdScriptNameFix
    Lint
    LintError
    Lobster
    Locale
    Lock
    Logger
    MD5
    MailExceptions
    MethodOverride
    NullLogger
    ParameterTypeError
    PostBodyContentTypeParser
    Printout
    ProcTitle
    Profiler
    Recursive
    Reloader
    Request
    ResponseHeaders
    RouteExceptions
    Runtime
    Sendfile
    SessionHash
    rack-contrib
    https://github.com/rack/rack-contrib
    

    View Slide

43. Rails
    

    View Slide

44. use Rack::Sendfile
    use ActionDispatch::Static
    use Rack::Lock
    use ActiveSupport::Cache::Strategy::LocalCache::Middleware
    use Rack::Runtime
    use Rack::MethodOverride
    use ActionDispatch::RequestId
    use Rails::Rack::Logger
    use ActionDispatch::ShowExceptions
    use ActionDispatch::DebugExceptions
    use ActionDispatch::RemoteIp
    use ActionDispatch::Reloader
    use ActionDispatch::Callbacks
    use ActiveRecord::Migration::CheckPending
    use ActiveRecord::ConnectionAdapters::ConnectionManagement
    use ActiveRecord::QueryCache
    use ActionDispatch::Cookies
    use ActionDispatch::Session::CookieStore
    use ActionDispatch::Flash
    use ActionDispatch::ParamsParser
    use Rack::Head
    use Rack::ConditionalGet
    use Rack::ETag
    run Rails.application.routes
    $ rake middleware
    

    View Slide

45. use Rack::Sendfile
    use ActionDispatch::Static
    use Rack::Lock
    use ActiveSupport::Cache::Strategy::LocalCache::Middleware
    use Rack::Runtime
    use Rack::MethodOverride
    use ActionDispatch::RequestId
    use Rails::Rack::Logger
    use ActionDispatch::ShowExceptions
    use ActionDispatch::DebugExceptions
    use ActionDispatch::RemoteIp
    use ActionDispatch::Reloader
    use ActionDispatch::Callbacks
    use ActiveRecord::Migration::CheckPending
    use ActiveRecord::ConnectionAdapters::ConnectionManagement
    use ActiveRecord::QueryCache
    use ActionDispatch::Cookies
    use ActionDispatch::Session::CookieStore
    use ActionDispatch::Flash
    use ActionDispatch::ParamsParser
    use Rack::Head
    use Rack::ConditionalGet
    use Rack::ETag
    run Rails.application.routes
    $ rake middleware
    

    View Slide

46. Rails.application.routes
    #=> ActionDispatch::Routing::RouteSet
    def initialize
    @set = Journey::Routes.new
    @router = Journey::Router.new @set
    end
    def call(env)
    req = ActionDispatch::Request.new(env)
    @router.serve(req)
    end
    

    View Slide

47. module ActionDispatch
    class Request < Rack::Request
    def initialize(env)
    super
    # ...
    end
    end
    end
    

    View Slide

48. use Rack::Sendfile
    use ActionDispatch::Static
    use Rack::Lock
    use ActiveSupport::Cache::Strategy::LocalCache::Middleware
    use Rack::Runtime
    use Rack::MethodOverride
    use ActionDispatch::RequestId
    use Rails::Rack::Logger
    use ActionDispatch::ShowExceptions
    use ActionDispatch::DebugExceptions
    use ActionDispatch::RemoteIp
    use ActionDispatch::Reloader
    use ActionDispatch::Callbacks
    use ActiveRecord::Migration::CheckPending
    use ActiveRecord::ConnectionAdapters::ConnectionManagement
    use ActiveRecord::QueryCache
    use ActionDispatch::Cookies
    use ActionDispatch::Session::CookieStore
    use ActionDispatch::Flash
    use ActionDispatch::ParamsParser
    use Rack::Head
    use Rack::ConditionalGet
    use Rack::ETag
    run Rails.application.routes
    $ rake middleware
    

    View Slide

49. use Rack::Sendfile
    use ActionDispatch::Static
    use Rack::Lock
    use ActiveSupport::Cache::Strategy::LocalCache::Middleware
    use Rack::Runtime
    use Rack::MethodOverride
    use ActionDispatch::RequestId
    use Rails::Rack::Logger
    use ActionDispatch::ShowExceptions
    use ActionDispatch::DebugExceptions
    use ActionDispatch::RemoteIp
    use ActionDispatch::Reloader
    use ActionDispatch::Callbacks
    use ActiveRecord::Migration::CheckPending
    use ActiveRecord::ConnectionAdapters::ConnectionManagement
    use ActiveRecord::QueryCache
    use ActionDispatch::Cookies
    use ActionDispatch::Session::CookieStore
    use ActionDispatch::Flash
    use ActionDispatch::ParamsParser
    use Rack::Head
    use Rack::ConditionalGet
    use Rack::ETag
    run Rails.application.routes
    $ rake middleware
    

    View Slide

50. use Rack::Sendfile
    use ActionDispatch::Static
    use Rack::Lock
    use ActiveSupport::Cache::Strategy::LocalCache::Middleware
    use Rack::Runtime
    use Rack::MethodOverride
    use ActionDispatch::RequestId
    use Rails::Rack::Logger
    use ActionDispatch::ShowExceptions
    use ActionDispatch::DebugExceptions
    use ActionDispatch::RemoteIp
    use ActionDispatch::Reloader
    use ActionDispatch::Callbacks
    use ActiveRecord::Migration::CheckPending
    use ActiveRecord::ConnectionAdapters::ConnectionManagement
    use ActiveRecord::QueryCache
    use ActionDispatch::Cookies
    use ActionDispatch::Session::CookieStore
    use ActionDispatch::Flash
    use ActionDispatch::ParamsParser
    use Rack::Head
    use Rack::ConditionalGet
    use Rack::ETag
    run Rails.application.routes
    $ rake middleware
    

    View Slide

51. More details about Rails on Rack:
    http://guides.rubyonrails.org/rails_on_rack.html
    

    View Slide

52. rack.hijack
    

    View Slide

53. env['rack.hijack?'] #=> true/false
    env['rack.hijack'] #=> .call
    env['rack.hijack_io'] #=> IO/Socket
    

    View Slide

54. app = Proc.new do |env|
    io = env['rack.hijack'].call
    begin
    io.write("Status: 200\r\n")
    io.write("Connection: close\r\n")
    io.write("Content-Type: text/plain\r\n")
    io.write("\r\n")
    10.times do |i|
    io.write("Line #{i + 1}!\n")
    io.flush
    sleep 0.1
    end
    ensure
    io.close
    end
    end
    

    View Slide

55. app = Proc.new do |env|
    io = env['rack.hijack'].call
    begin
    io.write("Status: 200\r\n")
    io.write("Connection: close\r\n")
    io.write("Content-Type: text/plain\r\n")
    io.write("\r\n")
    10.times do |i|
    io.write("Line #{i + 1}!\n")
    io.flush
    sleep 0.1
    end
    ensure
    io.close
    end
    end
    

    View Slide

56. app = Proc.new do |env|
    hijack = ->(io) {
    10.times do |n|
    io.write("Line #{n + 1}\n")
    io.flush
    sleep 0.1
    end
    io.close
    }
    headers = {'rack.hijack' => hijack}
    [200, headers, nil]
    }
    

    View Slide

57. • Supported by Passenger
    • Supported by Unicorn (for responses < 30s)
    • Supported by Puma
    • WEBrick only supports partial hijacking
    • Not supported by Thin (maybe?)
    

    View Slide

58. MyApp
    Server
    Internets Framework
    Server Framework
    Network Application
    HIJACK
    Rack
    

    View Slide

59. The future of Rack?
    https://github.com/tenderlove/the_metal
    https://gist.github.com/raggi/11c3491561802e573a47
    https://github.com/Wardrop/Rack-Next
    

    View Slide

60. Exercise
    https://github.com/yycruby/middleware_exercise
    git@github.com:yycruby/middleware_exercise.git
    

    View Slide