Wrap every method with just one line

Feature Flag 基盤構築の一環として実装したサーバーサイドロジックの紹介です。
Ruby において include するだけですべての method をトラップして実装を差し込む手法を用いて、クライアントにサーバーサイドロジックの一部を確認/上書きできる用になります。

Transcript

1. ©2020 Wantedly, Inc.
   Wrap every method
   With just another line
   Meguro.rb#30
   Jan 31, 2020 - Shimpei Otsubo
   

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2. ©2020 Wantedly, Inc.
   Shimpei Otsubo @potsbo
   Developer Experience Squad, Wantedly, Inc.
   Kubernetes
   Dev Tools
   CI / CD
   AuthN / Z
   Productivity Dvorak
   

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3. ©2020 Wantedly, Inc.
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   ࣗಈ΋खಈ΋
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   Ұ൪લͳΒport-forwardͱ͔Ͱߦ͚Δ͕ʜ
   ˞αʔϏεϝογϡͰղܾ͍ͨ͠ϨΠϠͰ΋͋Δʜ
   $4͕ࠞཚ
   ਓʹΑͬͯڍಈ͕ҟͳΔࣄ͕͋ͬͯ΋Կނ͔Θ͔Βͳ͍
   

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4. ©2020 Wantedly, Inc.
   AB ςετΛ؆୯ʹτάϧͰ͖Δextension࡞ͬͨ
   ˞ը૾͸αϯϓϧͰ͢
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   ͲΜͳflagͰࠓͷϖʔδΛrenderͯ͠΄͍͔͠ࢦఆͰ͖Δ
   

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5. ©2020 Wantedly, Inc.
   Thread.current
   resp header
   middleware
   ͲΜͳ஋Λ࢖͔ͬͨʁΛfeedback
   ͲΜͳ஋Λ࢖ͬͯ΄͍͔͠ʁΛࢦఆ
   Thread.current
   req header
   Header Λհͯ͠ methodͷධՁ஋Λ read /write
   )FBEFSͳͷͰNJDSPTFSWJDFͰ఻ൖՄೳ
   call
   return
   

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6. ©2020 Wantedly, Inc.
   ڵຯର৅ͷNFUIPEʹ͢΂ͯΛIPPL͢Δඞཁ͕͋Δ
   ͜ͷͨΊʹ͸
   

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7. ©2020 Wantedly, Inc.
   class Experiment
   def self.enable?(name, target)
   # some consistent logic here
   end
   end
   Experiment.enable?(:show_new_button, current_user)
   # => true or false
   Wantedly ʹ͓͚ΔABςετͷํ๏
   ಉҰͷuserʹରͯ͠͸ৗʹಉҰͷboolean͕ฦΔmethod
   

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8. ©2020 Wantedly, Inc.
   Thread.current͔Βuser͕ࢦఆͨ͠஋͕͋Ε͹ͦΕΛར༻
   ͳ͚Ε͹Thread.currentʹར༻ͨ͠஋Λ٧ΊΔ
   class Experiment
   def self.enable?(name, target)
   # some consistent logic here
   end
   def self.wrapped_enable?(name, target)
   request_value = Thread.current[:request][name]
   return request_value unless request_value.nil?
   actual_value = enable?(name, target)
   Thread.current[:response][name] = actual_value
   end
   end
   ˞Thread.currentͱheaderͷؒΛͭͳ͙middlewareΛผ్༻ҙ
   

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9. ©2020 Wantedly, Inc.
   Renameͯͦ͠ͷ··࢖͑ΔΑ͏ʹ͢Δ
   class Experiment
   def self.real_enable?(name, target)
   # some consistent logic here
   end
   def self.enable?(name, target)
   request_value = Thread.current[:request][name]
   return request_value unless request_value.nil?
   actual_value = real_enable?(name, target)
   Thread.current[:response][name] = actual_value
   end
   end
   

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10. ©2020 Wantedly, Inc.
    ҰൠԽͯ͠ΈΔ
    class FeatureFlag
    def self.intercept(name)
    request_value = Thread.current[:request][name]
    return request_value unless request_value.nil?
    actual_value = yield
    Thread.current[:response][name] = actual_value
    end
    end
    class Experiment
    def self.real_enable?(name, target)
    # some consistent logic here
    end
    def self.enable?(name, target)
    FeatureFlag.intercept(name) do
    real_enable?(name, target)
    end
    end
    end
    ϒϩοΫͰғΈ͑͢͞Ε͹Ͳ͜Ͱ΋PWFSSJEFՄೳʂ
    

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11. ©2020 Wantedly, Inc.
    ଞͷػೳͷग़͠෼͚ʹ΋࢖͑Δ͸ͣ
    

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12. ©2020 Wantedly, Inc.
    Helperͷ͍ΖΜͳmethod ͰػೳΛग़͠෼͚͍ͯ͠Δ৔ॴ͕͋Δ
    module I18nHelper
    # the new landing page currently supports only Japanese!!
    def show_new_landing_page?
    I18n.locale == :ja
    end
    end
    

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13. ©2020 Wantedly, Inc.
    ϒϩοΫͰғΉ͚ͩͰXSBQͰ͖Δ
    class FeatureFlag
    def self.intercept(name)
    ...
    end
    end
    module I18nHelper
    # the new landing page currently supports only Japanese!!
    def show_new_landing_page?
    FeatureFlag.intercept(:show_new_landing_page?) do
    I18n.locale == :ja
    end
    end
    end
    

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14. ©2020 Wantedly, Inc.
    ϒϩοΫͰғΉ͚ͩͰXSBQͰ͖Δ
    class FeatureFlag
    def self.intercept(name)
    ...
    end
    end
    module I18nHelper
    # the new landing page currently supports only Japanese!!
    def show_new_landing_page?
    FeatureFlag.intercept(:show_new_landing_page?) do
    I18n.locale == :ja
    end
    end
    end
    ຖճॻ͘ͷ͸ྲྀੴʹ໘౗
    

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15. ©2020 Wantedly, Inc.
    class FeatureFlag
    def self.intercept(name)
    ...
    end
    end
    module I18nHelper
    # the new landing page currently supports only Japanese!!
    def show_new_landing_page?
    FeatureFlag.intercept(:show_new_landing_page?) do
    I18n.locale == :ja
    end
    end
    end
    खಈͰίʔυΛ͍͡ΔͷͰ͸ͳ͘
    

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16. ©2020 Wantedly, Inc.
    class FeatureFlag
    def self.intercept(name)
    ...
    end
    end
    module I18nHelper
    include FeatureFlag
    def show_new_landing_page?
    I18n.locale == :ja
    end
    end
    *ODMVEF͚ͩͰղܾͰ͖ͨΒ޾ͤ
    Ұߦ௥Ճ͢Δ͚ͩʂʂ
    

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17. ©2020 Wantedly, Inc.
    Ͱ͖ΔΑ͏ʹͨ͠
    module FeatureFlag
    def self.included(base)
    base.class_eval do
    extend ClassMethods
    @_already_patched = []
    @_patch_target = base
    end
    end
    module ClassMethods
    def intercept(name)
    ...
    end
    def method_added(name)
    if !@_already_patched.include?(name) && self == @_patch_target
    orig_method_name = "_#{base}_orig".to_sym
    @_already_patched << name
    @_already_patched << orig_method_name
    alias_method orig_method_name, name
    

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18. ©2020 Wantedly, Inc.
    ॳظԽ
    module FeatureFlag
    def self.included(base)
    base.class_eval do
    extend ClassMethods
    @_already_patched = []
    @_patch_target = base
    end
    end
    module ClassMethods
    def intercept(name)
    ...
    end
    def method_added(name)
    if !@_already_patched.include?(name) && self == @_patch_target
    orig_method_name = "_#{base}_orig".to_sym
    @_already_patched << name
    @_already_patched << orig_method_name
    alias_method orig_method_name, name
    ͲͷNPEVMFͰJODMVEFͨ͠ͷ͔͓֮͑ͯ͘
    

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19. ©2020 Wantedly, Inc.
    module ClassMethods
    def intercept(name)
    ...
    end
    def method_added(name)
    if !@_already_patched.include?(name) && self == @_patch_target
    orig_method_name = "_#{base}_orig".to_sym
    @_already_patched << name
    @_already_patched << orig_method_name
    alias_method orig_method_name, name
    private orig_method_name
    define_method(name) do |*args|
    intercept(name) do
    send(old_name, *args)
    end
    end
    end
    super
    end
    end
    end
    ͢ͰʹXSBQ͍ͯ͠ͳ͍͔ͷ֬ೝ
    

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20. ©2020 Wantedly, Inc.
    module ClassMethods
    def intercept(name)
    ...
    end
    def method_added(name)
    if !@_already_patched.include?(name) && self == @_patch_target
    orig_method_name = "_#{base}_orig".to_sym
    @_already_patched << name
    @_already_patched << orig_method_name
    alias_method orig_method_name, name
    private orig_method_name
    define_method(name) do |*args|
    intercept(name) do
    send(old_name, *args)
    end
    end
    end
    super
    end
    end
    end
    طଘ࣮૷ͷୀආ
    

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21. ©2020 Wantedly, Inc.
    module ClassMethods
    def intercept(name)
    ...
    end
    def method_added(name)
    if !@_already_patched.include?(name) && self == @_patch_target
    orig_method_name = "_#{base}_orig".to_sym
    @_already_patched << name
    @_already_patched << orig_method_name
    alias_method orig_method_name, name
    private orig_method_name
    define_method(name) do |*args|
    intercept(name) do
    send(old_name, *args)
    end
    end
    end
    super
    end
    end
    end
    8SBQ࣮૷
    

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22. ©2020 Wantedly, Inc.
    αʔόʔͷڍಈ͕ݟ͑Δม͑ΒΕΔͱָ
    *ODMVEF͚ͩͰ͢΂ͯͷNFUIPEXSBQ͸Մೳ
    ଞʹ΋͍Ζ͍Ζͳ֦ு͕Ͱ͖Δ
    ςετ΋σόοά΋
    NFUIPE@BEEFEͰ௥Ճ͞ΕͨNFUIPEΛ͍͡Ε͹ྑ͍
    XSBQ@POMZGPP CBSͱ͔΋࡞ΕΔ
    

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